Characterization of plant growth promoting rhizobacteria (PGPR) isolated from the rhizosphere of Vigna radiata (mung bean)

The rhizosphere is the zone under influence of plant roots where various kinds of microbial activities occur which perform important functions such as increase uptake of nutrients for the host for their better growth and protection from several diseases caused by various phytopathogens. Keeping in this vital role performed by rhizospheric microbes, thirty-nine bacterial isolates were isolated on King's B and nutrient agar media from the rhizosphere region of mung bean plants. Among these isolates, foure were identified as Pseudomonas spp., Bacillus sp., Acinetobacter sp. on the basis of biochemical and 16 S rDNA gene sequencing analysis. All the isolates were screened in vitro for plant growth promoting attributes such as IAA production, phosphate solubilization, ammonia production, catalase production, siderophore production, and antagonistic activity against phytopathogenic Rhizoctonia solani, the causal organism of root rot in mung bean. All the bacterial strains showed significant PGPR attributes and were able to produce indole-3 -acetic acid (ranging from 45.66 mu g/ml to 111.94 mu g/ml). In addition, the isolated strains enhanced phosphate solubilization activity (ranging from 952.91 mu g/ml to 1341.24 mu g/ml). Out of all, Pseudomonas spp. showed most potent antifungal activities against R. solani. Thus, the current study has focused on the characterization of rhizobacteria isolated from the rhizosphere of healthy mung bean plant. The results showed that the isolates posses, multiple plant growth-promoting (PGP) traits and can be used as a potential candidate on the soil-plant system to increase their growth as well as productivity.