Abstract:[Background] Bacillus amyloliquefaciens ZG2 is an antagonistic bacterial strain with biocontrol effects that is isolated and screened from the surface of jujube fruits by our research team. It has an excellent prospect for application in the prevention and control of diseases of postharvest fruits and vegetables. [Objective] To analyze the genome information of strain ZG2, explore its functional genes and secondary metabolite gene resources, and provide a theoretical basis for application of this strain in the biocontrol of postharvest diseases of fruits and vegetables. [Methods] The growth curve of strain ZG2 was determined by a spectrophotometer. Illumina and PacBio platforms were used for whole genome sequencing. The sequencing data were used for genome assembly, gene prediction, functional annotation, and prediction of secondary metabolite biosynthetic gene clusters (BGCs). The inhibitory effect of strain ZG2 on Alternaria alternata was assessed based on the mycelial growth rate. Control effect experiments were conducted to evaluate the control effect of strain ZG2 on black spot of postharvest Yulu fragrant pears. [Results] B. amyloliquefaciens ZG2 showed slow growth, logarithmic growth, stable growth, and declined growth during 0–6 h, 6–26 h, 26–46 h, and 46–58 h, respectively. The collinearity analysis showed that B. amyloliquefaciens ZG2 shared close genetic relationships with B. velezensis FZB42 and B. amyloliquefaciens GKT04. The genome of B. amyloliquefaciens ZG2 had a total length of 4.13 Mb, with the G+C content of 46.09%, carrying 4 652 coding genes. The whole genome data were uploaded to NCBI with the accession number CP172418. A total of 4 539, 3 453, 4 197, 3 070, 541, 2 914, 350, 194, 162, and 2 914 genes were annotated in NR, Swiss-Prot, KEGG, COG, TCDB, GO, PHI, VFDB, CAZy, and Pfam databases, respectively. Multiple hydrolases were predicted, including lichenase/endo-beta-1,3-1,4-glucanase (EC 3.2.1.73), chitinase (EC 3.2.1.14), lysozyme (EC 3.2.1.17), and endo-beta-1,4-glucanase/ cellulase (EC 3.2.1.4). In addition, we identified 13 secondary metabolite BGCs, which encoded antimicrobial substances such as macrolactin H, bacillaene, fengycin, difficidin, bacillibactin, and bacilysin. Among them, three BGCs had low homology with the BGCs encoding known compounds, which indicated that strain ZG2 had the potential to synthesize novel and unique functional compounds. The fermentation broth of strain ZG2 inhibited the mycelial growth of A. alternata, showcasing the inhibition rate of 97.5%. The control effect of the strain on black spot of postharvest Yulu fragrant pears was 53.55% on day 7. [Conclusion] By whole genome sequencing, this study comprehensively reveals the composition and functions of the genome of strain ZG2. We delve into the gene expression and synthesis of antimicrobial organic compounds, predict the secondary metabolite BGCs, and explores the in vivo and in vitro control effects of the fermentation broth of strain ZG2 on A. alternata. The findings provide a theoretical basis for exploring the potential application value of strain ZG2 in the disease prevention and control of postharvest fruits and vegetables.
