[Diversity of siderophore-producing endophytic bacteria of Cymbidium goeringii roots]

In order to obtain the effective plant growth-promoting bacteria, we studied the diversity of siderophore-producing endophytic bacteria in the roots of Cymbidium goeringii.We screened for siderophore-producing bacteria from 189 root endophytic strains of Cymbidium goeringii by using chrome azurol S (CAS) agar plate assay. The diversity of siderophore-producing endophytic bacteria was investigated by 16S rRNA gene sequence analysis.We obtained 47 siderophore-producing strains (24.9% of the total strains). Sequence analysis revealed that 47 strains were members of 31 species of 17 genera in four phylogenetic groups (Alphaproteobacteria, Betaproteobacteria, Firmicutes, Actinobacteria). The dominant group was Actinobacteria (42.6%), and the dominant genera were Bacillus and Variovorax. The strains of Variovorax produced relatively high levels of siderophore. In addition, there may be two novel taxonomic units.The results show that there are abundant species diversity of siderophore-producing endophytic bacteria in the roots of Cymbidium goeringii.