Isolation and characterization of rhizospheric bacteria in soybean (Glycine max (L.) Merrill) cultivated on ferralsols of CuJut district, DakNong province, Vietnam

Abstract

Rhizobacteria in the ferralsols rhizosphere of soybean grown in CuJut district, DakNong province, highland of Vietnam was studied. A total of 63 isolates were isolated on two media (Burk’s N-free and NBRIP) from 24 soil rhizosphere samples were taken in 24 sites of this region and all of them have ability of nitrogen fixation and phosphate solubilization. The sequences from selected rhizobacteria (11 isolates) were analysed 16S rRNA gene fragments amplified from DNA using eubacterial universal primers (8F and 1492R) and sequenced. The results showed they had high degrees of similarity to those of the GenBank references strains (between 97% and 99%). From 11 isolates, 6 belonged to Bacilli while Proteobacteria having 2, and 3 were Alpha, and Gamma-Proteobacteria, respectively. Based on Pi value (nucleotide diversity), Bacilli group had highest Theta value and Thete values (per sequence) from S of SNP for DNA polymorphism were calculated from each group and Bacilli group had the highest values in comparison to others. There were 18/63 and 22/63 isolates producing IAA and siderophores, respectively. From these results showed that there are five strains as Bacillus subtilis CJ27, Acinetobacter lwoffii CJ28, Agrobacterium tumefaciens CJ32, Bacillus subtilis CJ33 and Bacillus subtilis CJL18 revealed promising candidates with multiple beneficial characteristics and they have the potential for application as inoculants adapted to poor soils and local crops because they are not only famous strains but also are safety strains for agricultural sustainable, especially for soybean cultivation on ferralsols in the future.