西藏开菲尔粒（俗称藏灵菇）是一种富含乳酸菌和酵母菌的紧密粘弹颗粒，其发酵乳因作为混合多菌株功能性发酵乳而受到关注。但由于西藏开菲尔粒增长速度过慢，需不断进行传代培养，尽管许多研究者都试图将开菲尔原粒中分离出的乳酸菌、酵母菌进行互配来模拟天然开菲尔粒的菌群结构，从而人工合成天然开菲尔粒，但均未成功。目前也无法在没有原西藏开菲尔粒（引子）的情况下，复原/培养出传代稳定的西藏开菲尔粒，这使西藏开菲尔的产业化、市场化难以实现。目前研究多集中在菌相分布、代谢产物分析及功能鉴定方面，而对开菲尔粒形成机制知之甚少。因此，探究西藏开菲尔粒中的天然混合菌株互作机制及其形成机理，对于开发出具有独立知识产权的本土化益生菌产品，推进益生菌产业化和功能型发酵乳制品发展具有重要意义。

本文对从西藏林芝和那曲地区的不同开菲尔粒进行微生物多样性及成膜特性分析，筛选鉴定可培养菌株，基于成膜特性，选取三株成膜能力强的菌株研究其菌体特性，进一步提取乳酸菌胞外多糖（EPS）和酵母菌细胞壁多糖（CWPS）进行结构解析。并采用体外培养和厌氧发酵粪便培养的方法评估EPS和CWPS的益生元特性，明确EPS和CWPS是否可以被分离自开菲粒中的微生物利用。进一步基于菌体相互作用，探究发酵体系中乳酸菌与酵母菌的代谢共生机制，基于群体感应现象，探究酵母菌体和发酵液对乳酸菌产生AI-2信号分子的影响，从而影响其成膜能力。基于多菌体及代谢产物的互作效应，模拟开菲尔生物膜的形成过程，借助开菲尔生物膜人工合成开菲尔粒，监测开菲尔粒形成过程中微观结构及物质的变化，旨在从乳酸菌和酵母菌互作、EPS结构、生物膜形成三个方面定性、定位、定量探讨西藏开菲尔粒的形成演替机制。为开菲尔乳制品的产业化发展提供理论支撑。研究内容和结果如下：

1. 不同来源西藏开菲尔粒微生物多样性分析及生物膜形成比较

对从西藏林芝和那曲地区采集的不同开菲尔粒进行微生物多样性及生物膜成膜特性分析，筛选鉴定可培养菌株，基于成膜特性，选取三株成膜能力强的菌株研究其菌体特性，结果表明从西藏灵芝地区和那曲地区采集的开菲尔粒（分别称为K1和K2），其颗粒形状和微观结构存在差异，且随着培养时间的增加，K1的增长率达到92.8 %显著高于K2（P < 0.05），提取K1和K2多糖并进行简单结构解析，单糖结果表明，K1和K2产生的EPS主要由葡萄糖、甘露糖、半乳糖和鼠李糖组成。K1和K2具有成膜性，且生物膜最佳成膜天数为10 d。对K1和K2的颗粒和发酵乳的微生物多样性进行分析，K1和K2微生物多样性存在差异，马乳酒样乳杆菌（Lactobacillus kefiranofaciens）是K1和K2中的优势细菌，K1和K2的优势真菌分别为马克思克鲁维酵母（Kluyveromyces marxianus）和Kazachstania turicensis。筛选K1和K2的可培养乳酸菌和酵母菌，选取K1中三株成膜能力强的副干酪乳杆菌（Lacticaseibacillus paracasei GL1，GL1）、瑞士乳杆菌（L. helveticus SNA12，SNA12）和K. marxianus G-Y4（G-Y4），对它们的生长特性、耐受特性和菌体特性进行研究，GL1和G-Y4具有较好的耐酸和耐胆盐能力。G-Y4的自聚性要优于两株乳酸菌。同时对三株菌株的粘附特性进行评价，它们Caco-2细胞都具有一定的粘附能力，其中GL1的粘附能力显著高于SNA12和G-Y4（P < 0.05）。三株菌株对两种病原菌的粘附都有良好的抑制作用。

2. 西藏开菲尔粒源乳酸菌胞外多糖和酵母菌细胞壁多糖的提取及结构表征

生物膜是指乳酸菌等微生物在生长过程中为适应生存环境而形成的一种由EPS、蛋白等细胞外多聚基质包裹微生物菌体形成的有序微生物体。EPS是构成生物膜的重要成分也是开菲尔粒基质的重要组成物质。因此通过液体发酵，对GL1产生的GL1-EPS和SNA12产生的粗多糖进行提取，得率分别为460.5 ± 4.82 mg/L和124 ± 3.03 mg/L。同时，通过碱提法，G-Y4产生的粗可溶性细胞壁多糖和不溶性细胞壁多糖（G-Y4-NCWP）的得率分别为849.7 ± 4.73 mg/L和5.92 ± 0.03 g/L。经过DEAE-52纤维素柱分离纯化，GL1-EPS得到纯化组分GL1-E1和GL1-E2，SNA12产生的粗多糖得到的纯化组分为SNA12-EPS，G-Y4产生的可溶性粗多糖分离纯化得到一个组分为G-Y4-SCWP。这些多糖组分均为高纯度的均一多糖。通过单糖组成、甲基化反应、气相色谱-质谱联用仪（GC-MS）和核磁共振波谱（NMR）结果表明，GL1-E1的主链由→4)-α-D-Glcp(1→，→3,4)-α-D-Manp(1→，→3,6)-α-D-Manp(1→，→6)-α-D-Manp(1→，→6)-α-D-Galp(1→组成，α-D-Glcp作为分支点与其连接。GL1-E2的主链由→4)-α-D-Glcp(1→，→3,4)-α-D-Manp(1→，→3,6)-α-D-Manp(1→，→6)-α-D-Galp(1→，→4)-β-D-Manp(1→)组成，侧链也由α-D-Manp残基组成。SNA12-EPS是有着→3)-β-D-Glcp-(1→4)-β-D-Galp-(1→4)-β-D-Galp-(1→的重复单元结构。G-Y4-SCWP为α-甘露聚糖，主链为→6)-α-D-Manp-(1→，分支结构为→2)-α-D-Manp-(1→。同时，G-Y4-NCWP是一种富含β-(1→3)、β-(1→2)或β-(1→4)键的葡聚糖。扫描电镜（SEM）分析结果显示五种多糖表现出不同的形态特征，这些差异可能由于多糖的结构不同导致。DSC结果显示五种多糖均具有较好的热稳定性，其中GL1-E1的热稳定性要优于其它四种多糖。

3. 乳酸菌与酵母菌多糖对西藏开菲尔粒源乳酸菌的促进作用及其肠道益生特性

通过体外模拟消化、体外纯菌培养和粪菌厌氧发酵实验探究GL1-E1、GL1-E2、SNA12-EPS和G-Y4-SCWP四种多糖对开菲尔粒中微生物的促进作用及其肠道益生特性，结果表明四种多糖不会被体外模拟胃肠液消化。以四种多糖作为唯一碳源对十株乳酸菌进行体外纯培养，结果显示，所选的十株菌均可不同程度地利用四种多糖，四种多糖尤其可促进开菲尔源分离的乳酸菌的生长，但是不同菌株之间的μmax、最大OD600nm、和lag值均存在较大差异。其中，R-12和R-17对SNA12-EPS和G-Y4-SCWP的利用与菊糖相差较小。GL1-E1、GL1-E2、SNA12-EPS和G-Y4-SCWP四种多糖体外厌氧发酵24 h后，发酵液的pH显著下降（P < 0.05），表明其可被肠道微生物利用降解。四种多糖均可促进SCFAs的产生，相比于GL1-E1和GL1-E2，SNA12-EPS和G-Y4-SCWP产生了较少的甲酸、乳酸、乙酸、丙酸和丁酸。此外，GL1-E1、GL1-E2、SNA12-EPS和G-Y4-SCWP分别通过提高Megamonas、Bifidobacterium、Lachnospiraceae和Phascolarctobacterium有益菌的相对丰度，降低有害菌Fusobacterium、Escherichia-Shigella和Klebsiella的丰度，调节肠道菌群结构，具有较好的肠道益生功能。

4. 西藏开菲尔粒源高产多糖乳酸菌与酵母菌共生机制探究

将GL1、SNA12和G-Y4混合培养，通过测定代谢产物、菌体表面特性和生物膜成膜能力研究乳酸菌与酵母菌的相互作用。结果表明：相比单一乳酸菌培养，添加G-Y4组可以促进乳酸菌的生长，降低发酵液的酸化程度；乳酸菌与酵母菌混合发酵可以加速乳酸的产生、促进氨基氮含量的积累和促进乙醇代谢物的产生； GL1+SNA12+G-Y4组的聚集能力和疏水性最强。对GL1、SNA12和G-Y4的不同组合菌体成膜能力进行了测定，GL1+SNA12+G‑Y4组的生物膜形成能力最强。添加G-Y4死细胞的细菌生物膜细胞附着更多的多糖和蛋白质；添加G-Y4-SCWP组生物膜上的细菌数量增加，而添加G-Y4-NCWP组的多糖含量增加。从群体感应水平分析，G-Y4活细胞和G-Y4的无细胞发酵液（Cell-free fermentation supernatant，CFS）可诱导GL1和SNA12产生自体诱导物-2（Autoinducer-2，AI-2）信号分子。同时，添加G-Y4（活细胞和CFS）在转录水平上可促进GL1和SNA12 LuxS基因的表达。对GL1+SNA12组和分别添加G-Y4活细胞、G-Y4-NCWP和CFS后形成生物膜的化学结构进行表征，红外光谱（FT-IR）结果表明，四组生物膜均出现蛋白质和多糖的吸收峰，G-Y4-NCWP组的多糖和蛋白质含量均高于其它三组，且生物膜中多糖的比例高于蛋白质。GL1+SNA12组和添加G-Y4的CFS组的单糖组成为半乳糖与葡萄糖，而添加G-Y4活细胞组和G-Y4-NCWP组的生物膜的单糖是由甘露糖、葡萄糖和半乳糖组成。此外，SEM结果表明添加G-Y4-NCWP组的细菌生物膜更加紧密。

5. 基于西藏开菲尔生物膜的生长模拟人工开菲尔粒形成

将GL1、SNA12、G-Y4及它们产生的多糖混合进行生物膜培养，其中菌株混合组为A组，菌株混合后加入可溶性多糖组为B组，菌株混合后加入可溶性多糖及不溶性多糖组为C组。借助光学显微镜和体视显微镜观察A、B、C组生物膜随培养时间的变化，通过原子力显微镜（AFM）观察了A、B、C三组的生物膜形貌，结果表明生物膜上细峰高度为C组>B组>A组。说明添加乳酸菌EPS和酵母菌CWPS均能促进开菲尔生物膜的形成。利用海藻酸钠包埋法，将A、B、C三组样品进行包埋制作人工开菲尔粒，A、B、C三组人工开菲尔粒随培养时间的增加蛋白质和多糖的含量增加，且C组含量高于B组，高于A组。人工开菲尔粒中GL1、SNA12和G-Y4三种菌的活菌数呈现较稳定的趋势。在培养的过程中，GL1活菌数高于SNA12和G-Y4，且开菲尔粒中的乳酸菌和酵母菌活菌数要高于发酵乳。3D扫描仪对人工开菲尔粒的生长状况进行记录，结果表明C组开菲尔粒增长率最快。此外。A、B、C三组人工开菲尔粒的SEM图像均可看到粗糙和不规则的多糖结构。培养至28 d时，开菲尔粒菌体附着更加密集。尤其对于C组，可明显观察到长杆菌、短杆菌和酵母菌的富集。即添加乳酸菌EPS和酵母菌CWPS组的开菲尔粒有望成为天然开菲尔粒的替代粒。

Tibetan kefir grains are compact viscoelastic particles rich in lactic acid bacteria and yeast. The fermented milk of Tibetan kefir grains has attracted much attention as a functional mixed multi-strain fermented milk. However, due to the slow growth rate of Tibetan kefir grains, it needs to be sub-cultured continuously. Although many researchers have tried to simulate the composition of natural kefir grains flora by combining the isolated bacteria in the original grains, but have not been successful in artificial synthesis. At present, it is impossible to recover/cultivate Tibetan kefir grains with stable passage without the original kefir grains. Now, most studies focus on the distribution of bacterial phase, metabolites, and their functions, but little is known about their formation mechanism. Therefore, it is of great significance to explore the interaction mechanism and formation mechanism of natural mixed strains in Tibetan kefir grains for developing localized probiotic products with independent intellectual property rights, promoting the industrialization of probiotics and the development of functional fermented dairy products.

In this paper, microbial diversity and membrane forming characteristics of different kefir grains from Nyingchi and Nagqu areas of Tibet were analyzed, and the culturable strains were screened and identified. Based on the biofilm forming characteristics, three strains with strong biofilm forming ability were selected to study their probiotics, and the extracellular polysaccharide (EPS) of LAB and cell wall polysaccharide (CWPS) of yeast were further extracted for structural analysis. The prebiotic properties of EPS and CWPS were evaluated by in vitro and anaerobic fermentation fecal culture to determine whether EPS and CWPS could be utilized by microorganisms isolated from kefir grains. Furthermore, the metabolic symbiosis mechanism between LAB and yeast in the fermentation system was explored based on the interaction of bacteria. Based on the interaction effect of multi-bacteria and metabolites, the formation process of kefir biofilm was simulated, and kefir grains were synthesized with the help of kefir biofilm to monitor the changes in microstructure and substances during the formation of kefir grains. The aim of this study is to explore the formation and succession mechanism of Tibetan kefirs grains from three aspects: the interaction between LAB and yeast, the structure of EPS and the formation of biofilm. Thus, it could provide theoretical support for the industrialization development of kefir dairy products. The research contents and results are as follows:

1 Microbial diversity analysis and biofilm formation in kefir grains from different sources in Tibet

Microbial diversity and biofilm forming characteristics of different kefir grains collected from Linzhi and Naqu of Tibet were analyzed, and the culturable strains were screened and identified. Based on the biofilm forming characteristics, three strains with strong biofilm forming ability were selected to study their probiotics. The results were as follows: The shape and microstructure of kefir grains (K1 and K2) collected from Linzhi and Naqu region of Tibet were different. With the increase of culture time, the proliferation rate of K1 reached 92.8 %, which was significantly higher than that of K2. The simple structure analysis of K1 and K2 polysaccharides was carried out. The results showed that the EPS of K1 and K2 were mainly composed of glucose, galactose, mannose, and rhamnose. K1 and K2 had the ability of biofilm formation, and the best biofilm formation time was 10 days. The analysis of the microbial diversity of K1 and K2 particles and fermented milk showed that K1 and K2 have different microbial diversity, and Lactobacillus kefiranofaciens is the dominant bacteria in K1 and K2. The dominant fungi of K1 and K2 were Kluyveromyces marxianus and Kazachstania turicensis, respectively. Culturable LAB and yeast in K1 and K2 were screened. Three strains with strong biofilm forming ability of Lacticaseibacillus paracasei GL1 (GL1), Lactobacillus helveticus SNA12 (SNA12) and K. marxianus G-Y4 (G-Y4) in K1 were selected. Their growth characteristics, tolerance characteristics and prebiotics were studied. GL1 and G-Y4 had good acid and bile salt resistance. The self-aggregation of G-Y4 was better than that of the other two strains. The adhesion characteristics of the three strains were evaluated, and the adhesion ability of GL1 to Caco-2 cells was higher than that of SNA12 and G-Y4 (P < 0.05). The three strains had good inhibition on the adhesion of the two pathogens.

2. Extraction and characterization of EPS from LAB and CWPS from yeast

GL1-EPS produced by GL1 and SNA12-EPS produced by SNA12 were extracted by liquid fermentation, and the yield of GL1-EPS and SNA12-EPS were 460.5 ± 4.82 mg/L and 124 ± 3.03 mg/L, respectively. Meanwhile, the yield of soluble cell wall polysaccharide (G-Y4-SCWP) and insoluble cell wall polysaccharide (G-Y4-NCWP) produced by G-Y4 was 849.7 ± 4.73 mg/L and 5.92 ± 0.03 g/L, respectively. After separation and purification on DEAE-52 cellulose column, GL1-EPS was purified to GL1-E1 and GL1-E2. The crude polysaccharide produced by SNA12 was purified into SNA12-EPS, and the crude polysaccharide produced by G-Y4 was purified into G-Y4-SCWP. These polysaccharide fractions were homogeneous polysaccharides of high purity. The results of monosaccharide composition, methylation reaction, chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR) showed that the main chain of GL1-E1 consisted of →4)-α-D-Glcp(1→，→3,4)-α-D-Manp(1→，→3,6)-α-D-Manp(1→，→6)-α- D-Manp(1→，→6)-α-D-Galp(1→, α-D-Glcp as a branch point. The main chain of GL1-E2 consists of →4)-α-D-Glcp(1→，→3,4)-α-D-Manp(1→，→3,6)-α-D-Manp(1→，→6) -α-D-Galp(1→，→4)-β-D-Manp(1→), and the side chain was composed of α-D-Manp residues. SNA12-EPS is a repeating unit structure with → 3)- β-D-Glcp -(1→4)- β-D-Galp-(1→4)-β-D-Galp-(1→, G-Y4-SCWP is α-mannan with main chain of →6)-α-D-Manp-(1→ and branch structure of →2)-α-D-Manp-(1→. Meanwhile, G-Y4- NCWP is a glucan rich in β-(1→3)、β-(1→2) or β-(1→4) bonds. Scanning electron microscopy (SEM) analysis showed that the five polysaccharides showed different morphological characteristics, which may be caused by the different structure of polysaccharides. DSC results showed that all the five polysaccharides had good thermal stability, and the thermal stability of GL1-E1 was better than that of the other four polysaccharides.

3. Promoting effects of LAB-EPS and yeast-CWPS on microorganisms in kefir grains and their intestinal probiotics function.

The promoting effects of GL1-E1, GL1-E2, SNA12-EPS and G-Y4-SCWP on microorganisms in kefir grains and their intestinal probiotics were investigated by simulated digestion, pure bacteria culture in vitro, and fecal bacteria anaerobic fermentation experiments. The results showed that the four polysaccharides could not be digested by simulated gastroenteric fluid in vitro. Ten strains of LAB were cultured in vitro with four kinds of polysaccharides as the sole carbon source. The results showed that all the ten strains had the enzyme system to digest polysaccharides, and they could utilize the four polysaccharides to different degrees, but the great differences in the μmax, maximum OD600nm, and lag values, among different strains were found. Among them, the utilization of SNA12-EPS and G-Y4-SCWP by R-12 and R-17 had little difference with inulin. After 24 h anaerobic fermentation of GL1-E1, GL1-E2, SNA12-EPS and G-Y4-SCWP, the pH of fermentation solution was significantly decreased (P < 0.05), which indicated that the polysaccharides could be utilized and degraded by intestinal microorganisms. All four polysaccharides promoted the production of SCFAs, and SNA12-EPS and G-Y4-SCWP produced less formic acid, lactic acid, acetic acid, propionic acid, and butyric acid than GL1-E1 and GL1-E2. In addition, GL1-E1, GL1-E2, SNA12-EPS and G-Y4-SCWP could improve the relative abundance of beneficial bacteria on Megamonas, Bifidobacterium, Lachnospiraceae, and Phascolarctobacterium, respectively and reduce harmful bacteria Fusobacterium, Escherichia-Shigella and Klebsiella to regulate the structure of gut microbiota. They had good intestinal prebiotic function.

4. Study on the symbiotic mechanism of high polysaccharide producing LAB and yeast in kefir grains of Tibet

GL1, SNA12 and G-Y4 were mixed for culture. Compared with single culture of LAB, the addition of G-Y4 could promote the growth of LAB and reduce the degree of acidification of fermentation broth. Different combinations of metabolites were measured. Mixed fermentation could accelerate the production of lactic acid, promote the accumulation of amino nitrogen content, and promote the production of ethanol metabolites. GL1+SNA12+G-Y4 group showed the strongest aggregation and hydrophobicity. The biofilm forming ability of GL1, SNA12, and G-Y4 was determined. The biofilm forming ability of GL1+SNA12+G‑Y4 group was the strongest. Bacterial biofilms supplemented with G-Y4 dead cells attached more polysaccharides and proteins than cells in the LAB culture group alone. The number of bacteria on the biofilm increased in the G-Y4-SCWP group, while the polysaccharide content increased in the G-Y4-NCWP group. By quorum sensing analysis, the production of Autoinducer-2 (AI-2) signaling molecules in GL1 and SNA12 was induced by living cells of G-Y4 and Cell-free supernatant (CFS). At the same time, the addition of G-Y4 (live cells and CFS) promoted the expression of GL1 and SNA12 LuxS genes at the transcriptional level. The chemical structure of biofilms formed in GL1+SNA12 group and after the addition of G-Y4 live cells, G-Y4-NCWP and CFS were characterized. FT-IR results showed that the absorption peaks of protein and polysaccharide appeared in all the four groups, and the contents of polysaccharide and protein in G-Y4-NCWP group were higher than those in the other three groups, and the proportion of polysaccharide in the biofilm was higher than that of protein. The monosaccharides in GL1+SNA12 group and G-Y4 CFS group were galactose and glucose, while the monosaccharides in the G-Y4 live cells group and G-Y4-NCWP group were mannose, glucose and galactose. The SEM results showed that the bacterial biofilms in the G-Y4-NCWP group were more compact.

5. Growth simulation of artificial kefir grains based on kefir biofilm

GL1, SNA12, G-Y4 and their polysaccharides were mixed for biofilm culture. The strains mixed group was group A, the strains mixed with soluble polysaccharide group was group B, and the strains mixed with soluble polysaccharide and insoluble polysaccharide group was group C. The change of biofilm in group A, B, and C with culture time was observed by optical microscopy and stereopicroscope. The morphologies of groups A, B and C were observed by atomic force microscopy (AFM). The results showed that the height of think peak on the biofilm was group C > Group B > Group A. These results indicated that the addition of EPS and CWPS could promote the formation of kefir biofilm. Using sodium alginate embedding method, samples from groups A, B and C were embedded to make artificial kefir grains. The contents of protein and polysaccharides in groups A, B, and C increased with the increasing culture time, and the contents in group C were higher than those in group B and group A. The viable numbers of GL1, SNA12, and G-Y4 in artificial kefir grains showed a stable trend. In the process of culture, the viable bacteria number of GL1 was higher than SNA12 and G-Y4, and the viable bacteria number of LAB and yeast in kefir grains was higher than that in fermented milk. The growth of artificial kefir grains was recorded by 3D scanner. The results showed that the proliferation rate of kefir grains in group C was the fastest. In addition. SEM images of artificial kefir granules in group A, B and C showed rough and irregular polysaccharide structure. The attachment of kefir grains was denser after 28 days of culture. Especially for group C, the enrichment of long bacillus, short bacillus and yeast can be obviously observed. Above all, the kefir grains added with EPS and CWPS group are most likely to be the substitute grains of natural kefir grains.

[1] 何川，章登政，张俊等，等．重铬酸钾-DNS比色法测定发酵液中乙醇含量[J]．生命科学研究，2013，17(1)：1－10．

[2] 廉雪花．酸马奶酒中乳酸菌产AI-2信号分子的研究[D]．内蒙古农业大学，2014．

[3] 井雪萍．开菲尔粒生物膜微生物多样性及其成膜特性研究[D]．哈尔滨工业大学，2016.

[4] 曲宜．天然西藏灵菇粒与人工合成粒形成特性的对比研究[D]．哈尔滨工业大学，2013．

[5] 张莉．植物乳杆菌的粘附特性研究及其在益生菌干酪中的应用[D]．吉林大学，2013．

[6] 周剑忠，黄开红，董明盛，等．微囊化纯培养发酵剂发酵奶与藏灵菇奶的比较研究[J]．食品与发酵工业，2007，8：173－176．

[7] Abdellah M, Ahcene H, Benalia Y, et al. Evaluation of biofilm formation by exopolysaccharide-producer strains of thermophilic lactic acid bacteria isolated from Algerian camel milk[J]. Emirates Journal of Food and Agriculture, 2015, 27:513-521.

[8] Abraham A G, Antoni G L. Characterization of milky kefir grains grown in milk and in soy milk[J]. Journal of Dairy Research, 1999(66):327-333.

[9] Adamberg S, Tomson K, Vija H, et al. Degradation of fructans and production of propionic acid by bacteroides thetaiotaomicron are enhanced by the shortage of amino acids[J]. Frontiers in Nutrition, 2014, 1:21.

[10] Aguilar-Uscanga B, Francois J M. A study of the yeast cell wall composition and structure in response to growth conditions and mode of cultivation[J]. Letters in Applied Microbiology, 2003, 37(3):268-274.

[11] Aizawa E, Tsuji H, Asahara T, et al. Possible association of Bifidobacterium and Lactobacillus in the gut microbiota of patients with major depressive disorder[J]. Journal of Affective Disorders, 2016, 202:254-257.

[12] Alraddadi F A J, Ross T, Powell S M. Evaluation of the microbial communities in kefir grains and kefir over time[J]. International Dairy Journal, 2022, 136: 105490.

[13] Alvarez-Martin P, Florez A B, Hernandez-Barranco A, et al. Interaction between dairy yeasts and lactic acid bacteria strains during milk fermentation. Food Control, 2008, 19(1):62-70.

[14] Alves-Santos A M, Sugizaki, C S A, Lima G C, et al. Prebiotic effect of dietary polyphenols: A systematic review[J]. Journal of Functional Foods, 2020, 74:104169.

[15] Andrade M C, Ribeiro A P D, Dovigo L N, et al. Effect of different pre-irradiation times on curcumin-mediated photodynamic therapy against planktonic cultures and biofilms of Candida spp[J]. Archives of Oral Biology, 2013, 58(2):200-210.

[16] Apar D K, Demirhan E, Ozel B. Kefir grain biomass production: influence of different culturing conditions and examination of growth kinetic models[J]. Journal of Food Process Engineering, 2017, 40:12332–12341.

[17] Astbury S, Atallah E, Vijay A, et al. Lower gut microbiome diversity and higher abundance of proinflammatory genus collinsella are associated with biopsy-proven nonalcoholic steatohepatitis[J]. Gut Microbes, 2020, 11(3):569-580.

[18] Azeredo J, Azevedo N F, Briandet R, et al. Critical review on biofilm methods[J]. Critical Reviews in Microbiology, 2017, 43(3):313-351.

[19] Babaei-Ghazvini M, Shahabi-Ghahfarrokhi I, Goudarzi V, et al. Preparation of UV-protective starch/kefiran/ZnOnanocomposite as a packaging film: Characterization[J]. Food Packaging Shelf, 2018, 16:103-111.

[20] Backhaus K, Heilmann C J, Sorgo AG, et al. A systematic study of the cell wall composition of Kluyveromyces lactis[J]. Yeast. 2010, 27:647-660.

[21] Barratt M J, Lebrilla C, Shapiro H Y, et al. The gut microbiota, food science, and human nutrition: A timely marriage[J]. Cell Host & Microbe, 2017, 22(2):134-141.

[22] Barukcic I, Gracin L, Jambrak A R, et al. Comparison of chemical, rheological and sensory properties of kefir produced by kefir grains and commercial kefir starter[J]. Mljekarstvo, 2017, 67(3):169-176.

[23] Bassler B L. How bacteria talk to each other: Regulation of gene expression by quorum sensing[J]. Current Opinion in Microbiology, 1999, 2(6):582-587.

[24] Bassler B L, Wright M, Silverman M R. Multiple signaling systems controlling expression of luminescence in Vibrio-harveyi-sequence and function of genes encoding a 2nd sensory pathway[J]. Molecular Microbiology, 1994, 13(2): 273-286.

[25] Bengoa A A, Iraporda C, Garrote G L, et al. Kefir micro-organisms: Their role in grain assembly and health properties of fermented milk[J]. Journal of Applied Microbiology, 2019, 126:686-700.

[26] Bernet M F, Brassart D, Neeser J R, et al. Adhesion of human bifidobacterial strains to cultured human intestinal epithelial cells and inhibition of enteropathogen-cell interactions[J]. Environmental Microbiology, 1993, 59:4121-4128.

[27] Bocci V A. The neglected organ: Bacterial flora has a crucial immunostimulatory role[J]. Perspectives in Biology and Medicine, 1992, 35(2):251-260.

[28] Bohrer J C, Kamemoto L E, Almeida P G, et al. Acute chorioamnionitis at term caused by the oral pathogen Fusobacterium nucleatum[J]. Hawai'i Journal of Medicine and Public Health, 2012, 71(10):280-281.

[29] Bourrie B C T, Willing B P, Cotter P D. The microbiota and health promoting characteristics of the fermented beverage kefir[J]. Front Microbiology, 2016, 7(647):1-17.

[30] Brackman G, Coenye T. Quorum sensing inhibitors as anti-biofilm agents[J]. Current Pharmaceutical Design, 2015, 21(1):5-11.

[31] Bradford M M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding[J]. Analytical Biochemistry, 1976, 72(1-2):248-254.

[32] Carasi P, Trejo F M, Perez P F, et al. Surface proteins from Lactobacillus kefir antagonize in vitro cytotoxic effect of Clostridium difficile toxins[J]. Anaerobe, 2012, 18(1):135-142.

[33] Cheirsilp B，Shimizu H，Shioya S. Enhanced kefiran production by mixed culture of Lactobacillus kefiranofaciens and Saccharomyces cerevisiae[J]. Journal of Biotechnology, 2003, 100(1):43-53.

[34] Cheirsilp B, Shoji H, Shimizu H, et al. Interactions between Lactobacillus kefiranofaciens and Saccharomyces cerevisiae in mixed culture for kefiran production[J]. Journal of Bioscience and Bioengineering, 2003, 96:279-284.

[35] Chen G, Xie M, Wan P, et al. Digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro by human intestinal microbiota of polysaccharides from Fuzhuan brick tea[J]. Food Chemistry, 2018, 244:331-339.

[36] Chen H C, Wang S Y, Chen M J, Microbiological study of lactic acid bacteria in kefir grains by culture-dependent and culture-independent methods[J]. Food Microbiology, 2008, 25:492-501.

[37] Chen L G, Liu J W, Ge X D, et al. Simulated digestion and fermentation in vitro by human gut microbiota of polysaccharides from Helicteres angustifolia L[J]. International Journal of Biological Macromolecules, 2020, 141:1065-1071.

[38] Chen R Z, Xu Y, Wu P, et al. Transplantation of fecal microbiota rich in short chain fatty acids and butyric acid treat cerebral ischemic stroke by regulating gut microbiota[J]. Pharmacological Research, 2019, 148:104403.

[39] Chen Y C. Immobilized Is ochrysis galbana (Haptophyta) for long-term storage and applications for feed and water quality control in clam (Meretrixlusoria) cultures [J]. Journal of Applied Phycology, 2003, 15:439-444.

[40] Chen T H, Wang S Y, Chen K N, et al. Microbiological and chemical properties of kefir manufactured by entrapped microorganisms isolated from kefir grains[J]. Journal of Dairy Science, 2008(92):3002-3013.

[41] Chen Z N, Shi J L, Yang X J, et al. Isolation of exopolysaccharide-producing bacteria and yeasts from Tibetan kefir and characterisation of the exopolysaccharides[J]. International Journal of Dairy Technology, 2016, 69(3):410-417.

[42] Cheong S H, Park J K, Kim B S, et al. Microencapsulation of yeast cells in the calcium alginate membrane[J]. Biotechnology Techniques, 1993, (7):879-884.

[43] Choi N-Y, Kim B-R, Bae Y-M, et al. Biofilm formation, attachment, and cell hydrophobicity of foodborne pathogens under varied environmental conditions[J]. Journal of the Korean Society for Applied Biological Chemistry, 2013, 56(2):207-220.

[44] Cockburn D W, Koropatkin N M. Polysaccharide degradation by the intestinal microbiota and its influence on human health and disease[J]. Journal of Molecular Biology, 2016, 428:3230-3252.

[45] Collado M C, Gueimonde M, Hernandez M, et al. Adhesion of selected Bifidobacterium strains to human intestinal mucus and the role of adhesion in enteropathogen exclusion[J]. Journal of Food Protection, 2005, 68(12):2672-2678.

[46] Cui Y H, Miao K, Niyaphorn S. Production of gamma-aminobutyric acid from lactic acid bacteria: A systematic review[J]. International Journal of Molecular Sciences, 2020,21(3):995.

[47] Das D, Baruah R, Goyal A. A food additive with prebiotic properties of an α-d-glucan from Lactobacillus plantarum DM5[J]. International Journal of Biological Macromolecules, 2014, 69:20-26.

[48] de Kievit, T R, Iglewski B H. Bacterial quorum sensing in pathogenic relationships[J]. Infection and Immunity, 2000, 68(9):4839-4849.

[49] De Vadder F, Kovatcheva-Datchary P, Goncalves D, et al. Microbiota-generated metabolites promote metabolic benefits via gut-brain neural circuits[J]. Cell, 2014, 156(1–2):84-96.

[50] De Vuyst L, Harth H, Van Kerrebroeck S, et al. Yeast diversity of sourdoughs and associated metabolic properties and functionalities[J]. International Journal of Food Microbiology, 2016, 239:26-34.

[51] Di T, Chen G, Sun Y, et al. In vitro digestion by saliva, simulated gastric and small intestinal juices and fermentation by human fecal microbiota of sulfated polysaccharides from Gracilaria rubra[J]. Journal of Functional Foods, 2018, 40:18-27.

[52] Ding R X, Goh W R, Wu R N, et al. Revisit gut microbiota and its impact on human health and disease[J]. Journal of Food and Drug Analysis, 2019, 27:623-631.

[53] Ding Y, Yan Y M, Peng Y J, et al. In vitro digestion under simulated saliva, gastric and small intestinal conditions and fermentation by human gut microbiota of polysaccharides from the fruits of Lycium barbarum[J]. International Journal of Biological Macromolecules, 2019, 125:751-760.

[54] Du B, Yang Y, Bian Z, et al. Molecular weight and helix conformation determine intestinal anti-inflammatory effects of exopolysaccharide from Schizophyllum commune[J]. Carbohydrate Polymers, 2017, 172:68-77.

[55] Dubois M, Gilles K A, Hamilton J K, et al. Colorimetric method for determination of sugars[J]. Nature, 1951, 168(4265):167.

[56] Dobson A, O’Sullivan O, Cotter P D, High-throughput sequence-based analysis of the bacterial composition of kefir and an associated kefir grain[J]. Fems microbiology letters, 2011, 320:56-62.

[57] Donaldson G P, Lee S M, Mazmanian S K, et al. Gut biogeography of the bacterial microbiota[J]. Nature Reviews Microbiology, 2015, 14(1):20-32.

[58] Dong J, Liu B, Jiang T M, et al. The biofilm hypothesis: The formation mechanism of Tibetan kefir grains[J]. International Journal of Dairy Technology, 2018, 71(1):44-50.

[59] Dubois M, Gilles K A, Hamilton J K, et al. Colorimetric method for determination of sugars and related substances[J]. Analytical Chemistry, 1956, 28(3):350-356.

[60] Eckburg P B, Bik E M, Bernstein C, et al. Diversity of the human intestinal microbial flora[J]. Science, 2005, 308:1635-1638.

[61] Ecklu-Mensah G, Gilbert J, Devkota S. Dietary Selection Pressures and Their Impact on the Gut Microbiome[J]. Cellular and Molecular Gastroenterology and Hepatology, 2022, 13(1):7-18.

[62] Esnaashari S S, Rezaei S, Mirzaei E, et al. Preparation and characterization of kefiran electrospun nanofibers[J]. International Journal of Biological Macromolecules, 2014, 70:50-56.

[63] Fadda M E, Mossa V, Deplano M, et al. In vitro screening of Kluyveromyces strains isolated from Fiore Sardo cheese for potential use as probiotics[J]. LWT-Food Science and Technology, 2017, 75:100-106.

[64] Farag M A, Jomaa S A, Abd El-Wahed A et al. The many faces of kefir fermented dairy products: quality characteristics, flavour chemistry, nutritional value, health benefits, and safety[J]. Nutrients, 2020, 12:346.

[65] Felizardo R J F, Watanabe I K M, Dardi P, et al. The interplay among gut microbiota, hypertension and kidney diseases: The role of short-chain fatty acids[J]. Pharmacological Research, 2019, 141:366-377.

[66] Feng M Q, Chen X H, Li C C, et al. Isolation and identification of an exopolysaccharide-producing lactic acid bacterium strain from Chinese paocai and biosorption of Pb(ii) by its exopolysaccharide[J]. Journal of Food Science, 2012, 77(6):T111-T117.

[67] Fleet G. The commercial and community significance of yeasts in food and beverage production[M]. Yeasts in Food & Beverages. Springer, Berlin, Heidelberg, 2006:1-12.

[68] Flint H J, Scott K P, Duncan S H, et al. Microbial degradation of complex carbohydrates in the gut[J]. Gut Microbes, 2012, 3(4): 289-306.

[69] Franco M C, Golowczyc M A, De Antoni G L, et al. Administration of kefir-fermented milk protects mice against Giardia intestinalis infection[J]. Journal of Medical Microbiology, 2013, 62:1815-1822.

[70] Friques A F, Arpini C M, Kalil I C, et al. Chronic administration of the probiotic kefir improves the endothelial function in spontaneously hypertensive rats[J]. Journal of Translational Medicine, 2015, 13:390-406.

[71] Frost G, Sleeth M L, Sahuri-Arisoylu M, et al. The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism[J]. Nature Communications, 2014, 5:3011.

[72] Fu Y S, Zhang J N, Chen K N, et al. An in vitro fermentation study on the effects of Dendrobium officinale polysaccharides on human intestinal microbiota from fecal microbiota transplantation donor[J]. Journal of Functional Foods, 2019, 53:44-53.

[73] Furukawa S, Nojima N, Yoshida K, et al. The importance of inter-species cell-cell co-aggregation between Lactobacillus plantarum ML11-11 and Saccharomyces cerevisiae BY4741 in Mixed-species biofilm formation[J]. Bioscience Biotechnology and Biochemistry, 2011, 75(8):1430-1434.

[74] Furukawa S, Yoshida K, Ogihara H, et al. Mixed-species biofilm formation by direct cell-cell contact between brewing yeasts and lactic acid bacteria[J]. Bioscience Biotechnology and Biochemistry, 2010, 74(11):2316-2319.

[75] Galinari É, Almeida-Lima J, Macedo G R, et al. Antioxidant, antiproliferative, and immunostimulatory effects of cell wall α-D-mannan fractions from Kluyveromyces marxianus[J]. International Journal of Biological Macromolecules, 2018, 109:837-846.

[76] Galinari E, Sabry D A, Sassaki G L, et al. Chemical structure, antiproliferative and antioxidant activities of a cell wall alpha-D-mannan from yeast Kluyveromyces marxianus[J]. Carbohydrate Polymers, 2017, 157:1298-1305.

[77] Gangoiti M V, Puertas A I, Hamet M F, et al. Lactobacillus plantarum CIDCA 8327: An alpha-glucan producing-strain isolated from kefir grains[J]. Carbohydrate Polymers, 2017, 170:52-59.

[78] Gao J, Gu F Y, He J, et al. Metagenome analysis of bacterial diversity in Tibetan kefir grains[J]. European Food Research and Technology, 2013, 236(3):549-556.

[79] Gao W, Zhang L W. Genotypic diversity of bacteria and yeasts isolated from Tibetan kefir[J]. International Journal of Food Science and Technology, 2018, 53:1535-1540.

[80] Gao W, Zhang L W. Comparative analysis of the microbial community composition between Tibetan kefir grains and milks[J]. Food Research International, 2019, 116:137-144.

[81] Garai-Ibabe G, Dueñas M T, Irastorza A, et al. Naturally occurring 2-substituted (1,3)-β-D-glucan producing Lactobacillus suebicus and Pediococcus parvulus strains with potential utility in the production of functional foods[J]. Bioresource Technology, 2010, 101(23):9254-9263.

[82] Garofalo C, Osimani A, Milanovi C V, et al. Bacteria and yeast microbiota in milk kefir grains from different Italian regions. Food microbiology, 2015, 49:123-133.

[83] Garrote G L, Abraham A G, Antoni G L. Chemical and microbiological characterization of kefir grains[J]. Journal of Dairy Research, 2001, 68(4):639-652.

[84] Ghasemlou M, Khodaiyan F, Jahanbin K, et al. Structural investigation and response surface optimisation for improvement of kefiran production yield from a low-cost culture medium[J]. Food Chemistry, 2012, 133:388-389.

[85] Ghoneum M, Gimzewski J. Apoptotic effect of a novel kefir product, PFT, on multidrug-resistant myeloid leukemia cells via a hole-piercing mechanism[J]. International Journal of Oncology, 2014, 44:830-837.

[86] Gibson G R, Hutkins R, Sanders M E, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics[J]. Nature Reviews Gastroenterology & Hepatology, 2017, 14(8):491-502.

[87] Gil-Rodríguez A M, Carrascosa A V, Requena T. Yeasts in foods and beverages: In vitro characterisation of probiotic traits[J]. LWT-Food Science & Technology, 2015, 64(2):1156-116.

[88] Gobbetti M, Corsetti A, Rossi J. The sourdough microflora-interactions between lactic acid bacteria and yeasts-metabolism of amino acids[J]. Applied Microbiology & Biotechnology, 1994, 41(4):456-460.

[89] Golnar R, Shahnaz S D, Fatemeh F R, et al. Comparison of two types of gels in improving burn wound[J]. Crescent Journal of Medical and Biological Sciences, 2014, 1:28-32.

[90] Golowczyc M A, Mobili P, Garrote A G, et al. Interaction between Lactobacillus kefir and Saccharomyces lipolytica isolated from kefir grains: Evidence for lectin-like activity of bacterial surface proteins[J]. Journal of dairy research, 2009, 76:111-116.

[91] Gonzalez-Orozco B D, Garcia-Cano I, Jimenez-Flores R, et al. Invited review: Milk kefir microbiota-Direct and indirect antimicrobial effects[J]. Journal of Dairy Science, 2022, 105(5):3703-3715.

[92] Gorreja F, Walker W A. The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies[J]. Gut Microbes, 2022, 14(1):2149214.

[93] Graciela L, Garrote, Analía G, et al. Microbial interactions in kefir: A natural probiotic drink. Wiley‐Blackwell. 2010.

[94] Gradova N B, Khokhlacheva A A, Murzina E D. Microbial components of kefir grains as exopolysaccharide kefiran producers[J]. Applied Biochemistry and Microbiology. 2015, 51:873-880.

[95] Grosu-Tudor S S, Angelescu I R, Brinzan, A. Characterization of S-layer proteins produced by lactobacilli isolated from Romanian artisan fermented products[J]. Journal of Applied Microbiology. 2023, 13(1).

[96] Gullon B, Gullon P, Tavaria F, et al. Structural features and assessment of prebiotic activity of refined arabinoxylooligosaccharides from wheat bran[J]. Journal of Functional Foods, 2014, 6:438-449.

[97] Gut A M, Vasiljevic T, Yeager T, et al. Kefir characteristics and antibacterial properties-potential applications in control of enteric bacterial infection[J]. International Journal of Dairy Technology, 2021, 118:105021.

[98] Guzel-Seydim Z, Wyffels J T, Seydim A C, et al. Turkish kefir and kefir grains: microbial enumeration and electron microscobic observation[J]. International Journal of Dairy Technology, 2005, 58(1):25-29.

[99] Habibi N, Soleimanian-Zad S, Zeinoddin M S. Optimization of kefir grains production by using taguchi technique and mini-fermentation[J]. World Applied Sciences Journal, 2011, 12:613-618.

[100] Han R, Pang D R, Wen L R, et al. In vitro digestibility and prebiotic activities of a sulfated polysaccharide from Gracilaria Lemaneiformis[J]. Journal of Functional Foods, 2020, 64:103652.

[101] Han X, Zhang L J, Wu H Y, et al. Investigation of microorganisms involved in kefir biofilm formation[J]. Antonie Van Leeuwenhoek, 2018, 111:2361-2370.

[102] Han X, Yi H X, Zhao S N, et al. Prospects of artificial kefir grains prepared by cheese and encapsulated vectors to mimic natural kefir grains[J]. Journal of Food Quality, 2020, 2020: 8839135.

[103] Haydee E R L, Audry P L, Adri ́an H M et al. Probiotic potential of Lactobacillus paracasei CT12 isolated from water kefir grains(tibicos) [J]. Current Microbiology, 2020, 77:2584-2592.

[104] Hidalgo-Cantabrana C, Sánchez B, Milani C, et al. Exopolysaccharide biosynthesis in Bifidobacterium spp.: Biological functions and a genomic overview[J]. Applied and Environmental Microbiology, 2014, 80:9-18.

[105] Hirayama S, Furukawa S, Ogihara H, et al. Yeast mannan structure necessary for co-aggregation with Lactobacillus plantarum ML11-11 [J]. Biochemical and Biophysical Resesrch Communications, 2012, 419:652-655.

[106] Hu J L, Nie S P, Min F F, et al. Artificial simulated saliva, gastric and intestinal digestion of polysaccharide from the seeds of Plantago asiatica L.[J]. Carbohydrate Polymers, 2013, 92(2):1143-1150.

[107] Hussein A S, Ibrahim G S, Asker M M S, et al. Exopolysaccharide from Lactobacillus helveticus: Identification of chemical structure and effect on biscuit quality[J]. Czech Journal of Food Sciences, 2010, 28(3):225-232.

[108] Hu T, Cui Y H, Zhang Y S, et al. Genome analysis and physiological characterization of four Streptococcus thermophilus strains isolated from Chinese traditional fermented milk[J]. Frontiers in Microbiology, 2020, 11:184.

[109] Ilikkan O K, Bagdat E S. Comparison of bacterial and fungal biodiversity of Turkish kefir grains with high-throughput metagenomic analysis[J]. LWT-Food Science and Technology, 2021, 152:112375.

[110] Jeong D, Kim D H, Kang I B, et al. Characterization and antibacterial activity of a novel exopolysaccharide produced by Lactobacillus kefiranofaciens DN1 isolated from kefir[J]. Food Control, 2017, 78:436-442.

[111] Ji, W Z, Zhu Y, Kan P C, et al. Analysis of intestinal microbial communities of cerebral infarction and ischemia patients based on high throughput sequencing technology and glucose and lipid metabolism[J]. Molecular Medicine Reports, 2017, 16(4):5413-5417.

[112] Jonathan M C, van den Borne J J G C, van Wiechen, P, et al. In vitro fermentation of 12 dietary fibres by faecal inoculum from pigs and humans[J]. Food Chemistry, 2012, 133(3):889-897.

[113] Juraskova D, Ribeiro S C, Silva C C G. Exopolysaccharides produced by lactic acid bacteria: From biosynthesis to health-promoting properties[J]. Foods, 2022, 11(2):156.

[114] Kabak B, Dobson A W. An introduction to the traditional fermented foods and beverages of Turkey[J]. Critical Reviews in Food Science and Nutrition, 2011, 51:248-260.

[115] Kanbak G, Uzuner K, Ol K K, et al. Effect of kefir and low-dose aspirin on arterial blood pressure measurements and renal apoptosis in unhypertensive rats with 4 weeks salt diet[J]. Clinical and Experimental Hypertension, 2014, 36:1-8.

[116] Kareb O, Aider M. Quorum Sensing circuits in the communicating mechanisms of bacteria and its implication in the biosynthesis of bacteriocins by lactic acid bacteria: A review[J]. Probiotics and Antimicrobial Proteins, 2020, 12(1):5-17.

[117] Karygianni L, Ren Z, Koo H, et al. Biofilm matrixome: Extracellular components in structured microbial communities[J]. Trends in Microbiology, 2020, 28:668-681.

[118] Kawarai T, Furukawa S, Ogihara H, et al. Mixed-species biofilm formation by lactic acid bacteria and rice wine yeasts[J]. Applied and Environmental Microbiology, 2007, 73 (14):4673-4676.

[119] Kim D H, Jeong D, Kim H, et al. Modern perspectives on the health benefits of kefir in next generation sequencing era: Improvement of the host gut microbiota[J]. Critical Reviews in Food Science and Nutrition, 2019, 59:17821793.

[120] Koo H, Yamada K M. Dynamic cell-matrix interactions modulate microbial biofilm and tissue 3D microenvironments[J]. Current Opinion in Cell Biology, 2016, 42:102-112.

[121] Korcz E, Ker´enyi Z. Varga L. Dietary fibers, prebiotics, and exopolysaccharides produced by lactic acid bacteria: Potential health benefits with special regard to cholesterol-lowering effects[J]. Food & Function, 2018, 9:3057-3068.

[122] Kumar M R, Yeap S K, Mohamad N E, et al. Metagenomic and phytochemical analyses of kefir water and its subchronic toxicity study in BALB/c mice[J]. BMC Complementary Medicine and Therapies, 2021, 21:183.

[123] Lebeer S, Verhoeven T L A, Francius G, et al. Identification of a gene cluster for the biosynthesis of a long, galactose-rich exopolysaccharide in Lactobacillus rhamnosus GG and functional analysis of the priming glycosyltransferase[J]. Applied and Environmental Microbiology, 2009, 75:3554-3563.

[124] Leite A M O, Miguel M A L, Peixoto R S, et al. Microbiological, technological and therapeutic properties of kefir: a natural probiotic beverage[J]. Brazilian Journal of Microbiology, 2013, 44(2):341-349.

[125] Li X W, Lv S, Shi T T, et al. Exopolysaccharides from yoghurt fermented by Lactobacillus paracasei: Production, purification and its binding to sodium caseinate[J]. Food Hydrocolloids, 2020, 102:105635.

[126] Li W, Ji J, Chen X H, Jiang M, et al. Structural elucidation and antioxidant activities of exopolysaccharides from Lactobacillus helveticus MB2-1[J]. Carbohydrate Polymers, 2014, 102:351-359.

[127] Li W, Xia X D, Tang W Z, et al. Structural characterization and anticancer activity of cell-bound exopolysaccharide from Lactobacillus helveticus MB2-1[J]. Journal of Agricultural and Food Chemistry, 2015, 63:3454-3463.

[128] Liu C, Li X, Li Y, et al. Structural characterization and antimutagenic activity of a novel polysaccharide isolated from Sepiella maindroni ink[J]. Food Chemistry, 2008, 110(4):807-813.

[129] Liu D, Tang W, Yin J Y, et al. Monosaccharide composition analysis of polysaccharides from natural sources: Hydrolysis condition and detection method development[J]. Food Hydrocolloids, 2021, 116:106641.

[130] Liu J R, Chen M J, Lin C W. Characterization of polysaccharide and volatile compounds produced by kefir grains grown in soymilk[J]. Journal of Food Science, 2002, 67(1):104-108.

[131] Liu J R, Che M. J, Lin C W. Antimutagenic and antioxidant properties of milk-kefir and soymilk-kefir[J]. Journal of Agricultural and Food Chemistry, 2005, 53(7):2467-2474.

[132] Liu H, Wang R Q, Ding K, et al. Purification and structure study on exopolysaccharides produced by Lactobacillus casei KL1 from Tibetan kefir[J]. Proceedings Paper, 2011, 221-228.

[133] Liu H, Xie Y H, Han T, et al. Purification and structure study on exopolysaccharides produced by Lactobacillus paracasei KL1-Liu from Tibetan kefir[J]. Advances in Materials Research-an International Journal. 2013, 781-784:1513-1518

[134] Liu Y N, Wu Q, Wu X Y, et al. Structure, preparation, modification, and bioactivities of beta-glucan and mannan from yeast cell wall: A review[J]. International Journal of Biological Macromolecules, 2021, 173:4458.

[135] Liu T, Zhou K, Yin S, et al. Purification and characterization of an exopolysaccharide produced by Lactobacillus plantarum HY isolated from home-made Sichuan Pickle[J]. International Journal of Biological Macromolecules, 2019, 134:516-526.

[136] Liu X M, Mao B Y, Gu J Y, et al. Blautia-a new functional genus with potential probiotic properties? [J]. Gut Microbes, 2021, 13(1):e1875796.

[137] Liu Z H, Li J Y, Liu H Y, et al. The intestinal microbiota associated with cardiac valve calcification differs from that of coronary artery disease[J]. Atherosclerosis, 2019, 284:121-128.

[138] Loeffler M, Hilbig J, Velasco L, et al. Usage of in situ exopolysaccharide-forming lactic acid bacteria in food production: Meat products – a new field of application? [J]. Comprehensive Reviews in Food Science and Food Safety, 2020, 19:2932-2954.

[139] Londero A., Hamet M F, De Antoni G L. Kefir grains as a starter for whey fermentation at different temperatures: Chemical and microbiological characterisation[J]. Journal of Dairy Research, 2012, 79:262-271.

[140] Looijesteijn P J, Hugenholtz J. Uncoupling of growth and exopolysaccharide production by Lactococcus lactis subsp. cremoris NIZO B40 and optimization of its synthesis[J]. Journal of Bioscience and Bioengineering, 1999, 88:178-182.

[141] Lyu Y L, Wu P P, Zhou J A, et al. Protoplast transformation of Kluyveromyces marxianus[J]. Biotechnology Journal, 2021, 16(12): e2100122.

[142] Ma Q W, Chai Y M, Yang Z B, et al. Deciphering the mechanisms of Limosilactobacillus fermentum L1 involved in conjugated linoleic acid regulated by LuxS/AI-2 quorum sensing[J]. LWT-Food Science and Technology, 2021, 154:112736.

[143] Maeda H, Zhu X, Suzuki S, et al. Structural characterization and biological activities of an exopolysaccharide kefiran produced by Lactobacillus kefiranofaciens WT-2B[J]. Journal of Agricultural and Food Chemistry, 2004, 52:5533-5538.

[144] Maeda H, Zhu X, Omura K, et al. Effects of an exopolysaccharide (kefiran) on lipids, blood pressure, blood glucose, and constipation[J]. Biofactors, 2004, 22:197-200.

[145] Maina N H, Tenkanen M, Maaheimo H, et al. NMR spectroscopic analysis of exopolysaccharides produced by Leuconostoc citreum and Weissella confuse[J]. Carbohydrate Research, 2008, 343:1446-1455.

[146] Magnusdottir S, Thiele I. Modeling metabolism of the human gut microbiome[J]. Current Opinion in Biotechnology, 2018, 51:90-96.

[147] Marchesi J R, Ravel J. The vocabulary of microbiome research: A proposal[J]. Microbiome, 2015, 3:31.

[148] Marco M L, Sanders M E, Ganzle M, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods[J]. Nature Reviews Gastroenterology & Hepatology, 2021, 18:196-208.

[149] Marketon M M, Glenn S A, Eberhard A. Quorum sensing controls exopolysaccharide production in Sinorhizobium meliloti[J]. Journal of Bacteriology, 2003, 185(1):325-331.

[150] Marshall S H, Gomez F A, Ramirez R, et al. Biofilm generation by Piscirickettsia salmonis under growth stress conditions: A putative in vivo survival/persistence strategy in marine environments[J]. Research in Microbiology, 2012, 163:557-566.

[151] Marshall V M, Cole W M, Brooker B E. Observations on the structure of kefir grains and the distribution of the microflora[J]. Journal of Bacteriology, 1984, 57:491-497.

[152] McCormack J. Quorum sensing, bacterial communication and new antibiotics[J]. Internal Medicine Journal, 2006, 36(12):757-758.

[153] Meng F Q, Zhao M W, Lu Z X. The LuxS/AI-2 system regulates the probiotic activities of lactic acid bacteria[J]. Trends in Food Science & Technology, 2022, 127:272-279.

[154] Micheli L, Uccelletti D, Palleschi C, et al. Isolation and characterisation of a ropy Lactobacillus strain producing the exopolysaccharide kefiran[J]. Applied Microbiology and Biotechnology, 1999, 53:69-74.

[155] Mitsumori M, Xu L M, Kajikawa H, et al. Possible quorum sensing in the rumen microbial community: Detection of quorum-sensing signal molecules from rumen bacteria[J]. FEMS Microbiology Letters, 2003, 219(1):47-52.

[156] Miyoshi Y, Okada S, Uchimura T. A mucus adhesion promoting protein, MapA, mediates the adhesion of Lactobacillus reuteri to Caco-2 human intestinal epithelial cells[J]. Bioscience Biotechnology and Biochemistry, 2006, 70(7):1622-1628.

[157] Mobili P, Serradell M Á, Trejo S A, et al. Heterogeneity of S-layer proteins from aggregating and non-aggregating Lactobacillus kefir strains[J]. Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2009, 95:363-372.

[158] Mokoena M P. Lactic acid bacteria and their bacteriocins: Classification, biosynthesis and applications against uropathogens: A mini-review[J]. Molecules, 2017, 22(8):1255.

[159] Monteagudo-Mera A, Rastall R A, Gibson G R, et al. Adhesion mechanisms mediated by probiotics and prebiotics and their potential impact on human health[J]. Applied Microbiology and Biotechnology, 2019, 103(16):6463-6472.

[160] Moradi, Zahra, Nastaran K. Kefiran, a branched polysaccharide: Preparation, properties and applications: A review[J]. Carbohydrate Polymers, 2019, 223:115100.

[161] Nalbantoglu U, Cakar A, Dogan H, et al. Metagenomic analysis of the microbial community in kefir grains[J]. Food Microbiology, 2014, 41:42-51.

[162] F, Junne S, Neubauer P. A big world in small grain: A review of natural milk kefir starters[J]. Microorganisms, 2020, 8:192-205.

[163] Nealson K H, Hastings J W. Bacterial bioluminescence: Its control and ecological significance[J]. Microbiological Reviews, 1979, 43(4):496-518.

[164] Nielsen B, Gurakan G C, Unlu G. Kefir: A multifaceted fermented dairy product[J]. Probiotics and Antimicrobial Proteins, 2015, 6(3-4):123-135.

[165] Nigam P S. An overview of microorganisms' contribution and performance in alcohol fermentation processing a variety of substrates[J]. Current Biotechnology, 2017, 6(1):9-16.

[166] Nikolic M, Jovcic B, Kojic M, et al. Surface properties of Lactobacillus and Leuconostoc isolates from homemade cheeses showing auto-aggregation ability[J]. European Food Research and Technology, 2010, 231:925-931.

[167] Novak M, Synytsya A, Gedeon O, et al. Yeast beta (1–3), (1–6)-D-glucan films: preparation and characterization of some structural and physical properties[J]. Carbohydrate Polymers, 2012, 87(4):2496-2504.

[168] Park H, Ye S, Ji Y. Autoinducer-2 associated inhibition by Lactobacillus sakei NR28 reduces virulence of enterohaemorrhagic Escherichia coli O157:H7[J]. Food Control, 2014, 45:62-69.

[169] Parolin C, Croatti V, Laghi L, et al. Lactobacillus biofilms influence anti-candida activity[J]. Frontiers in Microbiology, 2021, 12:750368.

[170] Perricone M, Bevilacqua A, Corbo M R, et al. Technological characterization and probiotic traits of yeasts isolated from Altamura sourdough to select promising microorganisms as functional starter cultures for cereal-based products[J]. Food Microbiology, 2014, 38:26-35.

[171] Peterson B W, He Y, Ren Y J, et al. Viscoelasticity of biofilms and their recalcitrance to mechanical and chemical challenges[J]. FEMS Microbiology Reviews, 2015, 39:234-245.

[172] Piermaria J A, Pinotti A, Garcia M A, et al. Films based on kefiran, an exopolysaccharide obtained from kefir grain: Development and characterization[J]. Food Hydrocolloids, 2009, 23:684-690.

[173] Ponomarova O, Gabrielli N, Sévin D C, et al. Yeast creates a niche for symbiotic lactic acid bacteria through nitrogen overflow[J]. Cell Systems, 2017, 5:345-357.

[174] Prado M R, Blandón L M, Vandenberghe L S, et al. Milk kefir: Composition, microbial cultures, biological activities, and related products[J]. Frontiers in Microbiology, 2015, 6:1177-1189.

[175] Prado M R M, Zibetti R G M, de Souza D, et al. Anti-inflammatory and angiogenic activity of polysaccharide extract obtained from Tibetan kefir[J]. Microvascular Research, 2016, 108:29-33.

[176] Prado M R M, Zibetti R G M, de Souza D, et al. Anti-inflammatory and angiogenic activity of polysaccharide extract obtained from Tibetan kefir[J]. Microvascular Research, 2016, 108:29-33.

[177] Preethy C, Nilanjana D. Biosurfactant production and diesel oil degradation by yeast species Trichosporon asahii isolated from petroleum hydrocarbon contaminated soil[J]. International Journal of Engineering Science & Technology, 2010, 2(12):6942-6953.

[178] Pretzer G, Snel J, Molenaar D, et al. Biodiversity-based identification and functional characterization of the mannose-specific adhesin of Lactobacillus plantarum[J]. Journal of Bacteriology, 2005, 187(17):6128-6136.

[179] Qin F, Sletmoen M, Stokke B T, et al. Higher order structures of a bioactive, water-soluble (1→3)-β-D-glucan derived from Saccharomyces cerevisiae[J]. Carbohydrate Polymers, 2013, 92(2):1026-1032.

[180] Reeves A E, Koenigsknecht M J, Bergin I L, et al. Suppression of clostridium difficile in the gastrointestinal tracts of germfree mice inoculated with a murine isolate from the family lachnospiraceae[J]. Infection and Immunity, 2012, 80(11):3786-3794.

[181] Ren D, Li C, Qin Y, et al. Inhibition of Staphylococcus aureus adherence to Caco-2 cells by Lactobacilli and cell surface properties that influence attachment[J]. Anaerobe, 2012,18(5):508-515.

[182] Rosa D D, Dias M.M. S, Grzes'kowiak L M, et al. Milk kefir: Nutritional, microbiological and health benefits[J]. Nutrition Research Reviews, 2017, 30(1):82-96.

[183] Rong Y, Yang R L, Yang Y Z, et al. Structural characterization of an active polysaccharide of longan and evaluation of immunological activity[J]. Carbohydrate Polymers, 2019, 213:247-256.

[184] Salas-Jara M J, Ilabaca A, Vega M, et al. Biofilm forming Lactobacillus: New challenges for the development of probiotics[J]. Microorganisms, 2016, 4:35.

[185] Salari A, Hashemi M, Afshari A. Functional properties of kefiran in the medical field and food industry[J]. Current Pharmaceutical Biotechnology, 2022, 23(3):388-395.

[186] Schiffrin E J, Blum S. Interactions between the microbiota and the intestinal mucosa[J]. European Journal of Clinical Nutrition, 2002, 56(3):S60-S64.

[187] Sharifi M, Moridnia A, Mortazavi D, et al., Kefir: A powerful probiotics with anticancer properties[J]. Medical Oncology, 2017, 34(11):183.

[188] Sheridan P O, Martin J C, Lawley T D, et al. Polysaccharide utilization loci and nutritional specialization in a dominant group of butyrate-producing human colonic Firmicutes[J]. Microbial Genomics, 2016, 2(2):000043.

[189] Shin N R, Whon T W, Bae J W. Proteobacteria: microbial signature of dysbiosis in gut microbiota[J]. Trends In Biotechnology, 2015, 33(9):496-503.

[190] Sieuwerts S, de Bok F A M, Hugenholtz J, et al. Unraveling microbial interactions in food fermentations: From classical to genomics approaches[J]. Applied and Environmental Microbiology. 2008, 74:4997-5007.

[191] Simova E, Beshkova D, Angelov A, et al. Lactic acid bacteria and yeasts in kefir grains and kefir made from them[J]. Journal of Industrial Microbiology & Biotechnology, 2002, 28:1-6.

[192] Speziale P, Pietrocola G, Rindi S, et al. Structural and functional role of Staphylococcus aureus surface components recognizing adhesive matrix molecules of the host[J]. Future Microbiology, 2009, 4(10):1337-1352.

[193] Sudun, Wulijideligen, Arakawa, K. Interaction between lactic acid bacteria and yeasts in airag, an alcoholic fermented milk[J]. Animal Science Journal, 2013, 84(1):66-74.

[194] Suharja A A S, Henriksson A, Liu S Q. Impact of Saccharomyces Cerevisiae on viability of probiotic Lactobacillus rhamnosus in fermented milk under ambient conditions[J]. Journal of Food Processing and Preservation, 2014, 38:326-337.

[195] Sun X N, Duan M M, Liu Y L, et al. The beneficial effects of Gracilaria lemaneiformis polysaccharides on obesity and the gut microbiota in high fat diet-fed mice[J]. Journal of Functional Foods, 2018, 46:48-56.

[196] Sun Y, Cui X, Duan M, et al. In vitro fermentation of κ-carrageenan oligosaccharides by human gut microbiota and its inflammatory effect on HT29 cells[J]. Journal of Functional Foods, 2019, 59:80-91.

[197] Sun Y P, Guan Y T, Wang D, et al. Potential roles of acyl homoserine lactone based quorum sensing in sequencing batch nitrifying biofilm reactors with or without the addition of organic carbon[J]. Bioresource Technology, 2018, 259:136-145.

[198] Sun Z, Kong J, Hu S, et al. Characterization of a s-layer protein from Lactobacillus crispatus k313 and the domains responsible for binding to cell wall and adherence to collagen[J]. Applied Microbiology Biotechnology, 2013, 97(5):1941-1952.

[199] Sun Z J, Lv G J, Li S Y. Probing the role of microenvironment for microencapsulated Sacchromyces cerevisiae under osmotic stress[J]. Journal of Biotechnology, 2007, 128:150-161.

[200] Sun Z L, Kong J, Hu S M, et al. Characterization of a S-layer protein from Lactobacillus crispatus K313 and the domains responsible for binding to cell wall and adherence to collagen[J]. Applied Microbiology and Biotechnology, 2013, 97(5):1941-1952.

[201] Swanson K S, Gibson G R, Hutkins R, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of synbiotics[J]. Nature Reviews Gastroenterology & Hepatology, 2020, 17:687-701.

[202] Szlufman C, Shemesh M. Role of probiotic bacilli in developing synbiotic food: Challenges and opportunities[J]. Frontiers in Microbiology, 2021, 12:638830.

[203] Tada S, Katakura Y, Ninomiya K, et al. Fed-batch coculture of Lactobacillus kefiranofaciens with Saccharomyces cerevisiae for effective production of kefiran[J]. Journal of Bioscience and Bioengineering, 2007, 103:557-562.

[204] Talu S, Pinto E P, Matos R S, et al. Surface dynamics, fractal features, and micromorphology analysis of kefir biofilms[J]. Microscopy Research and Technique, 2022, 85(5):1964-1975.

[205] Tan J, McKenzie C, Potamitis M, et al. The role of short-chain fatty acids in health and disease[J]. Advances in Immunology, 2014, 121:91-119.

[206] Tang N Y, Wang X M, Yang R, et al. Extraction, isolation, structural characterization and prebiotic activity of cell wall polysaccharide from Kluyveromyces marxianus[J]. Carbohydrate Polymers, 2022, 289:119457.

[207] Tang W Z, Dong M S, Wang W L, et al. Structural characterization and antioxidant property of released exopolysaccharides from Lactobacillus delbrueckii ssp bulgaricus SRFM-1[J]. Carbohydrate Polymers, 2017, 173:654-664.

[208] Taniguchi M, Tanaka T. Clarification of interactions among microorganisms and development of co-culture system for production of useful substances[J]. Recent Progress of Biochemical and Biomedical Engineering in Japan, 2004, 90:35-62.

[209] Terraf M C L, Tomas M S J, Nader-Macias M E F, et al. Screening of biofilm formation by beneficial vaginal lactobacilli and influence of culture media components[J]. Journal of Applied Microbiology, 2012, 113(6):1517-1529.

[210] Teschler J K, Zamorano-Sanchez D, Utada A S, et al. Living in the matrix: Assembly and control of Vibrio cholerae biofilms[J]. Nature Reviews Microbiology, 2015, 13:255-268.

[211] Tian J J, Zhang C P, Wang X M, et al. Structural characterization and immunomodulatory activity of intracellular polysaccharide from the mycelium of Paecilomyces cicadae TJJ1213[J]. Food Research International, 2021, 147:110515.

[212] Torino M I, Taranto M P, Sesma F, et al. Heterofermentative pattern and exopolysaccharide production by Lactobacillus helveticus ATCC 15807 in response to environmental pH[J]. Journal of Applied Microbiology, 2001, 91(5):846-852.

[213] Tyagi R, Sharma P, Nautiyal R, et al. Synthesis of quaternised guar gum using Taguchi L-(16) orthogonal array[J]. Carbohydrate Polymers, 2020, 237: 116136.

[214] Van Houdt R, Aertsen A, Michiels C W. Quorum-sensing-dependent switch to butanediol fermentation prevents lethal medium acidification in Aeromonas hydrophila AH-1N[J]. Research in Microbiology, 2007, 158(4):379-385.

[215] Van Wyk J, Witthuhn R C, Britz T J. Optimisation of vitamin B12 and folate pro-duction by Propionibacterium freudenreichii strains in kefir[J]. International Dairy Journal, 2011, 21:69-74.

[216] Verderosa A D, Totsika M, Fairfull-Smith K E. Bacterial biofilm eradication agents: A current review[J]. Frontiers in Chemistry, 2019, 7:824.

[217] Verstraeten N, Braeken K, Debkumari B, et al. Living on a surface: Swarming and biofilm formation[J]. Trends in Microbiology, 2008, 16(10):496-506.

[218] Viana R O, Magalhaes-Guedes K T, Braga R A. et al. Fermentation process for production of apple-based kefir vinegar: Microbiological, chemical and sensory analysis[J]. Brazilian Journal of Microbiology, 2017, 48:592-601.

[219] Vinderola C G, Reinheimer J A. Lactic acid starter and probiotic bacteria: a comparative "in vitro" study of probiotic characteristics and biological barrier resistance[J]. Food Research International, 2003, 36(9-10):895-904.

[220] Walsh A M, Crispie F, O’Sullivan O, et al. Species classifier choice is a key consideration when analysing low-complexity food microbiome data[J]. Microbiome, 2018. 6:50-57.

[221] Wang H, Wang C N, Guo M R. Autogenic successions of bacteria and fungi in kefir grains from different origins when sub-cultured in goat milk[J]. Food Research International, 2020, 138:109784.

[222] Wang J, Zhao X, Tian Z, et al. Characterization of an exopolysaccharide produced by Lactobacillus plantarum YW11 isolated from Tibet Kefir[J]. Carbohydrate Polymers, 2015, 125:16-25.

[223] Wang J J, Wu Z C, Wang S, et al. Inhibitory effect of probiotic Bacillus spp. isolated from the digestive tract of Rhynchocypris Lagowskii on the adhesion of common pathogenic bacteria in the intestinal model[J]. Microbial Pathogenesis, 2022, 169:1065623.

[224] Wang L, Zhong H, Liu K, et al. The evaluation of kefir pure culture starter: Liquid-core capsule entrapping microorganisms isolated from kefir grains[J]. Food Science and Technology International, 2016, 22(7):598-608.

[225] Wang M, Bi J. Modification of characteristics of kefiran by changing the carbon source of Lactobacillus kefiranofaciens[J]. Journal of the Science of Food and Agriculture, 2008, 88(5):763-769.

[226] Wang S Y, Chen K N, Lo Y M, et al. Investigation of microorganisms involved in biosynthesis of the kefir grain[J]. Food Microbiology, 2012, 32:274-285.

[227] Wang W, Li Z, Lv Z, et al. Effects of Kluyveromyces marxianus supplementation on immune responses, intestinal structure and microbiota in broiler chickens[J]. Plos One, 2017, 12(7):0180884.

[228] Wang Y, Xu N, Xi A. Effects of Lactobacillus plantarum MA2 isolated from Tibet kefir on lipid metabolism and intestinal microflora of rats fed on high-cholesterol diet[J]. Applied Microbiology and Biotechnology, 2009, 84:341-347.

[229] Wang Y P, Li C，Liu P, et al. Physical characterization of exopolysaccharide produced by Lactobacillus plantarum KF5 isolated from Tibet Kefir[J]. Carbohydrate Polymers, 2010, 82(3):895-903.

[230] Wasser S P. Medicinal mushrooms as a source of antitumor and immunomodulating polysaccharides[J]. Applied Microbiology and Biotechnology, 2002, 60(3):258-274.

[231] Weber K, Delben J, Bromage T G, et al. Comparison of SEM and VPSEM imaging techniques with respect to Streptococcus mutans biofilm topography[J]. FEMS Microbiology Letters, 2014, 350(2):175-179.

[232] Wu D T, Nie, X R, Gan, R Y, et al. In vitro digestion and fecal fermentation behaviors of a pectic polysaccharide from okra (Abelmoschus esculentus) and its impacts on human gut microbiota[J]. Food Hydrocolloids, 2021, 114:106577.

[233] Wu D T, Yuan Q, Guo H, et al. Dynamic changes of structural characteristics of snow chrysanthemum polysaccharides during in vitro digestion and fecal fermentation and related impacts on gut microbiota, Food Research International, 2021, 141:109888.

[234] Wu H, Moser C, Wang H Z, et al. Strategies for combating bacterial biofilm infections[J]. International Journal of Oral Science, 2015,7(1):1-7.

[235] Wu H, Rui X, Li W, et al. Mung bean (Vigna radiata) as probiotic food through fermentation with Lactobacillus plantarum B1-6[J]. LWT-Food Science and Technology, 2015, 63(1):445-451.

[236] Wu F, Guo X, Zhang J, et al. Phascolarctobacterium faecium abundant colonization in human gastrointestinal tract[J]. Experimental & Therapeutic Medicine, 2017, 14(4):3122-3126.

[237] Wu J N, Chen X T, Qiao K, et al. Purification, structural elucidation, and in vitro antitumor effects of novel polysaccharides from Bangia fuscopurpurea[J]. Food Science and Human Wellness, 2021, 10(1):63-71.

[238] Xia L, De J, Zhu M X, et al. Juniperus pingii var. wilsonii acidic polysaccharide: Extraction, characterization and anticomplement activity[J]. Carbohydrate Polymers, 2020, 231: 115728.

[239] Xie N, Zhou T, Li B. Kefir yeasts enhance probiotic potentials of Lactobacillus paracasei H9: The positive effects of coaggregation between the two strains[J]. Food Research International, 2012, 45(1):394-401.

[240] Xu B Y, Han Y P W. Oral bacteria, oral health, and adverse pregnancy outcomes[J]. Periodontology, 2022, 89(1):181-189.

[241] Xu X, Xu P, Ma C, et al. Gut microbiota, host health, and polysaccharides[J]. Biotechnology Advances, 2013, 31(2):318-337.

[242] Yan J K, Li L, Wang Z M, et al. Structural elucidation of an exopolysaccharide from mycelial fermentation of a Tolypocladium sp fungus isolated from wild Cordyceps sinensis[J]. Carbohydrate Polymers, 2010, 79(1):125-130.

[243] Yang X, Li A Q, Li X X, et al. An overview of classifications, properties of food polysaccharides and their links to applications in improving food textures[J]. Trends in Food Science & Technology, 2020, 102:1-15.

[244] Yiannikouris A, Francois J, Poughon L, et al. Alkali extraction of β-D-glucans from Saccharomyces cerevisiae cell wall and study of their adsorptive properties toward zearalenone[J]. Journal of Agricultural & Food Chemistry, 2004, 52(11):3666-3673.

[245] Yin W, Wang Y T, Liu L et al. Biofilms: The microbial "protective clothing" in extreme environments[J]. International Journal of Molecular Sciences, 2019, 20(14):3423.

[246] Yuan K Y, Hou L L, Jin Q Q,et al. Comparative transcriptomics analysis of Streptococcus mutans with disruption of LuxS/AI-2 quorum sensing and recovery of methyl cycle[J]. Archives of Oral Biology, 2021, 127:105137

[247] You X, Li Z, Ma K et al. Structural characterization and immunomodulatory activity of an exopolysaccharide produced by Lactobacillus helveticus LZ-R-5[J]. Carbohydrate Polymers, 2020, 235:115977.

[248] You X, Yang L, Zhao X J, et al. Isolation, purification, characterization and immunostimulatory activity of an exopolysaccharide produced by Lactobacillus pentosus LZ-R-17 isolated from Tibetan kefir[J]. International Journal of Biological Macromolecules, 2020, 158:408-419.

[249] Young M, Davies M J, Bailey D, et al. Characterization of oligosaccharides from an antigenic mannan of Saccharomyces cerevisiae[J]. Glycoconjugate Journal, 1998, 15(8):815-822.

[250] Zannini E, Waters D M, Coffey A, et al. Production, properties, and industrial food application of lactic acid bacteria-derived exopolysaccharides[J]. Applied Microbiology and Biotechnology, 2016, 100(3):1121-1135.

[251] Zhao J, Quan C S, Jin L M, et al. Production, detection and application perspectives of quorum sensing autoinducer-2 in bacteria[J]. Journal of Biotechnology, 2018, 268:53-60.

[252] Zhao L. The gut microbiota and obesity: From correlation to causality[J]. Nature Reviews Microbiology, 2013, 11(9):1-9.

[253] Zhang G H, Zhang W Z, Sun L J, et al. Preparation screening, production optimization and characterization of exopolysaccharides produced by Lactobacillus sanfranciscensis Ls-1001 isolated from Chinese traditional sourdough[J]. International Journal of Biological Macromolecules, 2019, 139:1295-1303.

[254] Zhang S, He B, Ge J B, et al. Extraction, chemical analysis of Angelica sinensis polysaccharides and antioxidant activity of the polysaccharides in ischemia-reperfusion rats[J]. International Journal of Biological Macromolecules, 2010, 47(4):546-550.

[255] Zhang Y, Gu Y, Wu R, et al. Exploring the relationship between the signal molecule AI-2 and the biofilm formation of Lactobacillus sanfranciscensis[J]. LWT-Food Science and Technology, 2021, 154:112704.

[256] Zheng J S, Wittouck S, Salvetti E, et al. A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae[J]. International Journal of Systematic and Evolutionary Microbiology, 2020, 70:2782-2858.

[257] Zhou B, Li Y K, Pei Y T, et al. Quantitative relationship between biofilms components and emitter clogging under reclaimed water drip irrigation[J]. Irrigation Science, 2013, 31(6): 1251-1263.

[258] Zhou J Z, Liu X, Jiang H. et al. Analysis of the microflora in Tibetan kefir grains using denaturing gradient gel electrophoresis. Food Microbiology, 2009, 26(8):770-775.

[259] Zhou Y, Cui Y H, Qu X J. Exopolysaccharides of lactic acid bacteria: Structure, bioactivity and associations: A review[J]. Carbohydrate Polymers, 2019, 207:317-332.