Isolation and Characterization of Plant Growth-Promoting Bacillus amyloliquefaciens Strain sks_bnj_1 and its Influence on Rhizosphere Soil Properties and Nutrition of Soybean (Glycine max L. Merrill)

Abstract

The objective of this work was to isolate and characterize Bacillus bearing multiple plant growth-promoting traits from diseased roots of soybean and to further assess its inoculation effect on soil rhizosphere properties and nutrition in soybean. The isolate was putatively identified as Bacillus on the basis of cultural characteristics and FAMEs profile, and further sequencing of 16S rRNA gene revealed 98.7% similarity to Bacillus amyloliquefaciens and designated as strain sks_bnj_1 (AY 932823). The strain possessed multiple plant growth-promoting traits such as siderophore production, indole-3-acetic acid-like-compounds, ACC deaminase, phosphatases, phytases, HCN, cellulases, zinc solubilization and antagonisms to soil-borne pathogens. Microcosm study using soybean as an indicator crop revealed that inoculation of this strain sks_bnj_1 significantly increased rhizosphere soil properties (enzyme activities, IAA production, microbial respiration, microbial biomass-C), and nutrient content in straw (K, P, Zn, Fe, Cu, Mn) and seeds (K, P, Fe, Mn) of soybean over uninoculated control. This study suggests that inoculation of B. amyloliquefaciens sks_bnj_1 improves most of the rhizosphere properties, plant growth, nutrient assimilation and yield of soybean and has potential to be promoted as a bioinoculant for soybean production following proper field evaluation.