Análises comparativas e funcionais de duas linhagens de Bacillus paralicheniformis isoladas do solo da Bahia revelam homogeneidade da espécie e metabólitos bioativos de potencial biotecnológico

Abstract

The genus Bacillus encompasses a widely studied group of bacteria, harboring species that significantly impact various industries. Many species are analyzed for their biotechnological and industrial potential, including the production of secondary metabolites, their use as biocontrol agents in plants, potentially reducing conventional chemical pesticide use, and their association with the diets of livestock like chickens, pigs, and cattle. However, due to divergences between taxonomic identification techniques such as MALDI-TOF and more recent, precise methods like Next-Generation Sequencing (NGS), inconsistencies in Bacillus species distinction have been observed. This is attributed to the high degree of similarity among organisms within the group, especially for recently described and less-studied species such as B. paralicheniformis. The group's recent description in 2015 highlights the scarcity of phylogenomic and comparative studies that analyze this species in isolation and contribute to understanding its genetic behavior. In this context, the present study aimed to identify and characterize isolates BAC30 and BAC220 using NGS, which were both confirmed as B. paralicheniformis and included in comparative and phylogenomic analyses with 28 other strains of the species to examine the group's genetic repertoire. Subsequently, functional annotation of BAC30 and BAC220 was performed, focusing on the species' biotechnological potential. Results showed that the isolates' identification highlights the relevance of NGS as the gold standard for taxonomic identification. Despite the high similarity among B. paralicheniformis strains, they exhibit an open pangenome with a high proportion of accessory genes, contrasting with core genes. This indicates the species' ubiquity and its propensity for acquiring new genes that favor survival in diverse niches and contribute to symbiosis with other organisms. Functional analyses of the isolates revealed few resistance genes, and demonstrated the production of relevant metabolites like bacitracin, riboflavin, and heme, along with genes related to nitrogen fixation in plants. Although in vitro analyses are necessary to confirm gene expression, these isolates show potential for biotechnological application, either in the isolated production of these metabolites and/or by acting as biocontrol bacteria in in vivo models, primarily with plants, but also with livestock and humans.