一株拮抗香蕉枯萎镰刀菌稀有放线菌的分离及鉴定

Isolation and Identification of a Strain of Rare Actinomycetes with Antagonistic Activity against Fusarium oxyporm f. sp. cubense

本研究采用苯酚、干热、SDS和超声波四种不同的预处理方法从五指山原始林区采集的土样中选择性分离得到的702株稀有放线菌,共筛选出4株具有拮抗香蕉枯萎镰刀菌活性的菌株,经过复筛,获得一株高活性的拮抗菌210-1-61。通过对其进行形态鉴定、生理生化特征鉴定和16S rDNA序列分析,结果表明该菌株与M.pattaloongensis JCM12833T进化关系最近,其16S rDNA序列同源性最高,达98.89%;其形态与生理生化特性也与小单孢菌属M.pattaloongensis JCM12833T很接近。此外,我们还构建了与该菌株同源性较高的模式菌株16S rDNA序列的聚类分析图,结果发现该菌株与M.pattaloongensis JCM12833T稳定单独构成一个分支,二者亲缘关系最近,初步鉴定该菌株为Micromonospora.pattaloongensis。本研究为今后探讨小单孢菌属稀有放线菌对香蕉尖孢镰刀菌具有拮抗活性提供研究实验材料。

In this research, we selectively isolated a total of 702 rare actinomycets strains from the soil samples of Wuzhishan Primitive Area by using four different pretreatment methods of phenol, dry heat, SDS and ultrasonic and totally screened 4 strains which had antagonistic activity against Fusarium oxyporm f.sp.cubense. After secondary screenning, we obtained a strain named 210-1-61 with a rather higher antagonistic activity. We further studied the phenotypic and physiological characteristics and 16S rDNA sequences of strain 210-1-61, the results showed that 210-1-61 strain had the closest evolving relationship with Micromonospora pattaloongensis JCM12833T, with the highest sequence homologous of 98.89%. Additionally, the phenotypic and physiological characteristics of 210-1-61 strain were also very close to those ofMicromonospora pattaloongensis JCM12833T. Furthermore, we still constructed the cluster diagram of 16S rDNA sequence between 210-1-61 strain and its higher homologous model strains, the results were found that this strain steadily constituted a separate branch with M. pattaloongensis JCM12833T, reflecting the closest relation of them, we preliminarily identified this strain as a member of the genus Micromonospora pattaloongensi. Consequently, this research would provide an experiment material for discussing the rare actinomycetes of Micromonospora genus with antagonistic activity agaist Fusarium oxyporm f.sp.cubense in the future.