Characterization of the chemical fungicides-responsive and bacterial pathogen-preventing Bacillus licheniformis in rice spikelet

Seed borne bacterial pathogens cause severe yield loss and biotoxin contamination in rice, leading to an increasing concern on the global food supply and environmental safety. Plant native microbes play an important role in defending against diseases, but their actions are often influenced by the chemical fungicides applied in the field. Here, Bacillus licheniformis mmj was isolated from rice spikelet, which uniquely showed not only the fungicide-responsiveness but also the broad-spectrum antimicrobial activity against major rice bacterial pathogens including Xanthomonas oryzae pv. oryzae, Burkholderia plantarii and Burkholderia glumae. To understand the hallmark underlying the environmental adaption and antimicrobial activity of B. licheniformis mmj, the genome sequence was determined by SMRT and subjected to bioinformatics analysis. Genome sequence analysis enabled to identification of a set of the antimicrobial-resistance and antibacterial activity genes together with an array of harsh environment-adaptive genes. Moreover, B. licheniformis mmj metabolites were analyzed with gas chromatography coupled to triple quadrupole mass spectrometry, and the volatile components that were linked with the antimicrobial activity were preliminarily profiled. Collectively, the present findings reveal the genomic and metabolic landscapes underlying the fungicide-responsive B. licheniformis, which offers a new opportunity to design harsh environment-adaptive biopesticides to cope with the prevalent bacterial phytopathogens.