Diversity and Seasonal Fluctuations of Endophytic Bacteria Isolated from the Root Tissues of Cymbidium faberi

The paper investigated the seasonal variations in the community structure of endophytic bacteria in the root tissues of Cymbidium faberi Rolfe.A total of 207 bacterial isolates were obtained in different seasons.Based on the pattern of amplified ribosomal DNA restriction analysis(ARDRA) using restriction enzyme Alu I,the bacteria were grouped into 25 operational taxonomic units(OTUs).Phylogenetic analysis based on 16S rDNA gene homological data showed that all isolates affiliated to nine genera,consisting of Bacillus,Burkholderia,Paenibacillus,Pseudomonas,Microbacterium,Rhizobium,Lysinibacillus,Cohnella and Brevibacterium.Bacillus dominated among the bacterial isolates,followed by Paenibacillus and Burkholderia.Isolate diversity was lowest in summer and highest in September.The correlation between the community structure of endophytic bacteria and seasonal factors reached a highly significant level(p<0.001).However,the dominant species of the bacterial communities in Cymbidium faberi did not change significantly.