根腐病又称干腐病，是白术种植中的重要病害之一。其发病症状为根茎变褐色至腐烂，地上部分开始萎蔫，根茎切面可见维管束变为褐色。后期根茎全部变为海绵状黑色干腐，植株枯死，极易从土壤中连根拔起。对广大药农而言，根腐病已严重影响了白术的产量和品质。 本实验主要通过组织分离法及稀释平板法，从发病植株的根部和正常植株的根际土壤分别分离到一株疑似致病真菌及四株疑似致病真菌的拮抗细菌。通过经典形态学方法和对该真菌核糖体RNA的ITS区域（18S rDNA -5.8S-28S rDNA）的扩增、测序、ITS序列的同源性分析比较和系统发育树的构建，将其归类于镰刀菌属（Fusarium），并将其命名为Fusarium sp. FO14。根据Koch法则对其致病性的鉴定工作正在进行中。从正常植株根际土壤稀释悬液中分离到的拮抗细菌，通过平板对峙法，选择对尖孢镰刀菌抑制效果较好的一株菌进行鉴定，并对该菌对一些其它致病性真菌的抑制效果进行了初步研究。通过生理生化特性鉴定，16s rDNA序列的测定、序列分析及构建系统发育树，将其归类于芽孢杆菌属，并命名为Bacillus sp. BS14。 在运用组织分离法分离白术根腐病病原菌的过程中，我们还分离到一株产红色色素的细菌，根据其生理生化特性，参照《伯杰氏细菌鉴定手册》和《常见细菌鉴定手册》，并结合16s rDNA序列的比对分析，将其归类于沙雷氏菌属，并将其命名为Serratia sp. FS14。该菌在pH 4-10的条件下均能生长，并能够耐受10 % 的NaCl。此外，Serratia sp. FS14还能分泌耐高温的DNA酶和蛋白水解酶，而该细菌的最高生长温度仅为42C。这种能分泌具有耐高温特性的胞外酶的现象在沙雷氏菌属中还未见报道。

Root-rot disease, also called dry-rot disease, was a serious disease of the cultivated Atractylodes macrocephala Koidz. The rhizomes of diseased plants would turn to be swollen and decayed with a brown colour at the cutting interface of the rhizomes. Finally, the disease led the plant to die, resulting in a remarkable loss to the farmers. A suspicious pathogen of the root-rot disease was isolated from the root tissue of the diseased Atractylodes macrocephala Koidz and four antagonistic bacteria strains were also isolated from the rhizosphere soil of the healthy Atractylodes macrocephala Koidz which was culviated in Jurong, the major cultivation place in Jiangsu Province. The fungus was identified as a species of Fusarium and named as Fusarium sp. FO14 by combining the morphology of the asexual spores and the analysis of its ITS sequence. The isolate with best anti Fusarium sp. FO14 activity was chosen for the further study. It was identified as Bacillus and named as Bacilllus sp. BS14 by combining the physiological, biochemical characters and the analysis of the 16S rDNA sequence. The antifungal activity against some other plant pathogen was also studied.