Isolation, identification, and whole genome analysis of a strain against Zanthoxylum bungeanum root rot

Abstract:

[Background] It remains a challenge to prevent and control Zanthoxylum bungeanum root rot in production, and the screening of biocontrol bacteria for the development of microbial agents seems to be a promising solution. [Objective] To analyze the genetic information of the antagonistic strain T-1, explore the root rot-antagonizing gene clusters, and reveal the antagonistic mechanism. [Methods] The methods of plate confrontation, morphological observation, physiological and biochemical index determination, and molecular biology were used to isolate and identify the antagonistic bacteria. The whole genome of the strain was sequenced, followed by sequence analysis and comparative genomics analysis. [Results] The strain was identified as Bacillus velezensis and numbered T-1. It inhibited 72% of the Fusarium solani, the pathogen of Z. bungeanum root rot, and hindered the growth of the front end of the mycelia. The results of in vitro antagonism experiments showed that T-1 had a wide range of antibacterial activities and had certain antagonistic effect on Z. bungeanum root pieces in vitro. Its whole-genome sequence data were submitted to SRA of NCBI to yield the accession number of SRX11086663. The genome was 3 886 726 bp, with GC content of 46.42% and 4 015 coding genes (89.74% of the genome). Comparative genomics analysis suggested that it had a high homology with the model strain B. velezensis FZB42, and the antagonistic gene cluster prediction indicated 12 gene clusters encoding the secondary metabolites in T-1 genome. Eight of them had functions known (butirosin A/butirosin B, macrolactin H, backland, fengycin, difficidin, bacillibactin, bacilysin, and surfactant), and the rest four had functions unknown. [Conclusion] This paper dissects the whole genome of B. velezensis T-1 and clarifies the gene clusters related to antagonism, which can serve as a reference for further research on the molecular antibacterial mechanism of this strain.

Key words:Bacillus velezensis;whole genome sequence;antagonist genes;secondary metabolites