Effect of halotolerant plant growth promoting rhizobacteria inoculation on soil microbial community structure and nutrients

Halophytes are potential sources of salt-tolerant bacteria with plant growth enhancing abilities. Previously, our group has isolated plant growth promoting rhizobacteria (PGPR) from the roots of a halophyte (Arthrocnemum indicum) and tested for their abilities to enhance the peanut growth. The resilience of native soil microbial community to exogenous inoculation of PGPR is of growing concern as change in microbial community structure impacts on soil-plant-microbe interaction. Therefore, the aim of the present study was to examine the influence of inoculation of PGPR isolated from halophytes on the native soil microbial community in the field grown peanut (Arachis hypogaea L.). The PGPR had significantly influenced and enhanced the availability of nutrients (N, P, K and Fe) in soil. Alkaline phosphatase activity was significantly improved in the bacteria inoculated soils, except MBE03 (Ochrobactrum anthropic), in comparison to the control soil where the highest increase was observed in the soil inoculated with MBE02 (Klebsiella sp.). There was a significant influence of bacterial treatments on the contents of total PLFAs, Gram-positive and actinomycetes PLFAs. The contents of these PLFAs were maximum in soil inoculated with MBE01 (Agrobacierium tumefaciens). The multivariate analysis of PLFA profiles exhibited that the microbial community structure of soil was not significantly affected by the bacterial inoculation. Our results suggest that the inoculation with beneficiary bacteria does not perturb the natural soil microbial community.