2种嵩草属牧草休眠期内生细菌多样性研究

采用稀释平板法从两种嵩草属牧草休眠期根和种子中分离到23株内生细菌,测定了其抑菌、溶磷、固氮和产IAA等生物学功能,并通过16S rDNA 基因序列分析进行了鉴定。结果表明,两牧草根和种子中内生细菌的数量和群落组成存在明显差异;线叶嵩草内生细菌的种类比矮生嵩草丰富;矮生嵩草根部内生细菌比种子中丰富,而线叶嵩草种子内生细菌较根部丰富;种子存放时间影响内生细菌数量;20株可继代培养内生细菌中具有抑菌、溶磷、固氮和产IAA生物功能的菌株分别占总菌株数的35%,55%,45%和25%。获得15株内生细菌的16S rDNA 基因序列,经同源性比较,其分别属于芽孢杆菌属(Bacillus)、叶杆菌属(Phyllobacterium)、葡萄球菌属(Staphylococcus)、类芽孢杆菌属(Paenibacillus)、微杆菌属(Microbacterium)、原小单孢菌属(Promicromonospora)和鞘氨醇盒菌属(Sphingopyxis),且芽孢杆菌属细菌为其优势种群。

Diversity of endophytic bacteria isolated from Kobresia during winter dormancy

Twenty three strains of endophytic bacteria were isolated from the roots and seeds of dormant plants in winter of two species of Kobresia,using the dilution plate method.The isolated bacteria were identified by sequence analysis of their 16S rDNA.Then their biological properties,including antimicrobial activity,phos-phorus solubilisation,nitrogen fixation and production of IAA,were determined.There were significant differ-ences in the number of endophytic bacteria and their community composition in the roots and seeds of the two Kobresia species.Kobresia capillifolia had a higher species diversity of endophytic bacteria than Kobresia hu-milis .Endophytic bacteria were more abundant in roots than in seeds for K .humilis ,but the opposite was true in K .capillifolia.The amount of endophytic bacteria was affected by the seed storage time.Twenty strains among the isolated endophytic bacteria displayed biological activity.including antimicrobial properties, phosphorus solubilisation,nitrogen fixation and production of IAA.The,numbers of strains with these respec-tive capabilities were 35%,55%,45% and 25%,respectively,of the total number of bacteria.Fifteen taxa were identified among the 16S rDNA gene sequences of the endophytic bacteria isolated.They included the genera Bacillus ,Phyllobacterium,Staphylococcus ,Paenibacillus ,Microbacterium,Promicromonospora and Sphin-gopyxis.Among these,Bacillus was the dominant species.