Complete genome sequencing of Bacillus velezensis Jin12 revealed its great ability for starch degradation in flue-cured tobacco leaves

Bacillus velezensis Jin12 with great starch degradation ability was isolated from stored tobacco lamina. In this study, PacBio sequencing technique was employed to analyze the genome of strain Jin12. The results revealed that the strain Jin12 genome is 4,057,213 bp in size, with a GC content of 46.33%, and encodes a total of 4,165 genes. GO annotation showed that the genes in strain Jin12 were enriched in the terms: catalytic activity, binding and transporter activity. COG annotation demonstrated that most genes in strain Jin12 were involved in amino acid transport and metabolism, transcription, and carbohydrate transport and metabolism. Sequence similarity searches using the CAZyme database helped identify the enzyme repertoire of strain Jin12 involved in starch degradation. We identified four α-amylases in the genome of strain Jin12 that likely participated in starch degradation. The experiment involving spray application of strain Jin12 bacterial suspension demonstrated that strain Jin12 degraded starch in tobacco leaves from different geographical origins, confirming its role in starch degradation. The current study enhances our understanding of the starch degradation mechanism from a genetic perspective and facilitates the application of starch-degrading strains in improving tobacco quality.