Diversity and growth promotion of endophytic diazotrophic bacteria isolated from Bryophyllum pinnatum

Abstract:

[Background] Endophytic diazotrophic bacteria can colonize within plants to provide nutrients for plants and promote plant growth through metabolism. [Objective] We studied the diversity of endophytic diazotrophic bacteria isolated from Bryophyllum pinnatum. [Methods] Endophytes were isolated and purified from surface sterilized plant tissues. Nitrogen-fixation ability of the isolates was tested by acetylene reduction assay. SDS-PAGE patterns of the whole-cell protein electrophoresis and IS-PCR DNA finger-printings were used to group these isolates. The representative strains were identified by physiological and biochemical characteristics, and the 16S rRNA gene sequence analysis. The growth promotion of nitrogen fixation, secretion of auxin and ACC deaminase, siderophore production, solubilizing phosphorus and potassium were determined. [Results] A total of 26 endophytic diazotrophic bacteria were isolated from Bryophyllum pinnatum and classified into 5 groups, belonging to 5 species of 4 genera. All representative strains had various plant growth promoting activity. [Conclusion] Endophytes isolated from Bryophyllum pinnatum have abundant genetic diversity and growth promoting characteristics.

Key words:Bryophyllum pinnatum, Diazotrophic bacteria, Endophytic bacteria, Growth promotion, New species