Characterization of effective bio-control agent Bacillus sp. SRB 27 with high salt tolerance and thermostability isolated from forest soil sample

Abstract

A potential antagonist Bacillus sp. SRB 27, against Fusarium oxysporum, Rhizoctonia solani and Alternaria solani was obtained from forest soil sample by carrying out in vitro and in vivo screening techniques. This study reports the identification and characterization of a Bacillus sp. SRB 27 that may be used as a bio-control agent against the plant diseases in crop plants. It was identified as Bacillus sp. SRB 27 based on 16S rDNA sequence analysis and biochemical tests. The isolate showed a wide range of antifungal activity in vitro against a number of phytopathogens such as F. oxysporum, Alternaria and Rhizoctonia in terms of percentage of growth inhibition which were 76.78, 78.57 and 77.55%, respectively. Strain SRB 27 was tolerant to high salt concentration up to 13%, was phosphate solubilizer, proteolytic and amylase positive and coagulase negative. It had compatibility with broad spectrum of fungicides with field recommended dose. Apart from the antagonistic activities, it showed a positive effect on the growth of the castor and cotton plants (both under seed and soil treatments) in comparison with control (non-inoculated). The growth parameters of the test plant surpassed the control in all the cases.