Whole-genome analysis of the benzoic acid-degrading bacterium Bacillus halotolerans B28 to reveal its phytoprobiotic effects

Benzoic acid is a representative allelochemical in soils affected by continuous cropping obstacles, and it is also a typical aromatic pollutant, causing a direct or indirect inhibition on crop growth. In this study, a strain B28 that was isolated from the rhizosphere of peanut by using benzoic acid as the sole carbon source and sequenced. Strain B28 contained a single circular chromosome, the complete genome size was 4,132,583 bp, the average GC was 43.89%, with 3928 predicted genes, and based on phylogenomic analyses, B28 was designated as Bacillus halotolerans. The strain B28 with outstanding abilities to biodegrade benzoic acid, enhance plant growth and control soil-borne diseases, which were the key to the phytoprobiotic functions. Genome mining revealed the potential genomic properties associated with plant growth promotion, such as aromatic xenobiotics biodegradation, IAA synthesis, biofilm formation, chemotaxis motility and secondary metabolite synthesis. The effects of strain B28 on the growth of Arachis hypogaea L. (peanut) was evaluated, and the physiological parameters of peanut such as fresh weight, dry weight, plant height and root length were significantly higher after inoculating strain B28. Overall, our present results indicate that Bacillus halotolerans B28 is a potential PGPR strain for benzoic acid bioremediation and organic agriculture application.