Antimicrobial activity of environmental Bacillus spp. and Peribacillus spp. isolates linked to surfactin, fengycin, bacillibactin and lantibiotics

Bacillus and closely related species are amongst the most exploited organisms for the development of novel bioactive formulations in sustainable agriculture. These bacteria produce a wide arsenal of bioactive compounds, such as antimicrobial peptides which are gaining increasing attention. Using an in-silico approach we characterised the whole genomes of five environmental isolates belonging to the Bacillus subtilis, Peribacillus simplex and Bacillus cereus clade with antimicrobial potential. We showed that the isolates contain genomic sequences for a wide range of secondary metabolites, including lipopeptides surfactin, fengycin, the siderophore bacillibactin or several promising lantipeptides. Ex situ production of antimicrobial substances was confirmed in vitro, detecting synergistic effects between isolates from the same origin. The strains furthermore exhibited a strong capacity of biofilm formation in silico and in vitro, although no synergy occurred. Regarding safety properties, all strains were found to harbour virulence and virulence-associated factors including antibiotic resistance genes. In summary, this study provides valuable insights into the genetic make-up and variations of spore-formers derived from olive orchards, which can be useful for the development of antimicrobial agents in sustainable agriculture.