软腐白菜根系土壤中湖生代夫特菌的分离和鉴定

Isolation and identification of a Delftia lacustris strain in rhizospheric soil of Chinese cabbage soft rot

目的筛选并鉴定软腐白菜根系土壤中分离出的细菌。方法从河南省大白菜田成熟白菜病株根系土壤采集样品,利用模拟原环境的培养基成分和条件,对样品中的细菌进行分离和培养。对菌株进行形态学观察、生理生化特征鉴定以及16S r RNA基因序列测定、比对分析和系统发育树构建,对菌株进行初步分类鉴定。结果分离到的一株编号为Q2S2-18A2的菌株16Sr DNA与代夫特菌属内的Delftia lacustris 332 T(EU888303)具有最高的相似性,相似值为98.60%。结论模拟原环境培养基,结合经典分类学方法和16S r RNA基因序列比对分析、构建系统发育树,可分离并鉴定软腐白菜根系土壤中的机会致病菌湖生代夫特菌。

Objective To isolate and identify Delfiia lacustris strain from rhizospheric soil of Chinese cabbage soft rot. Methods Based on the artificial Chinese cabbage medium, the bacteria from rhizospheric soils were isolated. According to their analysis of 16S rRNA gene sequence homology as well as their morphological features, physiological and biochemical analysis, the isolated strains were identified. Results An opportunistic pathogenic bacterial strain was found. The standard strain exhibited the highest levels（98.60%）of similarity to the Delfiia lacustris 332 7（EU888303）. Its taxonomic status was also confirmed by phylogenetic tree. This strain was finally identified as Delfiia lacustris. Conclusion There is a opportunistic pathogenic microorganism, Delftia lacustris,in the rhizospheric soil of Chinese cabbages.