Distribution of antimicrobial peptide biosynthetic gene markersin plant-associated Bacillus spp. and relationships with antagonistic activityagainst bacterial plant pathogens

Abstract: A large collection of Bacillus isolates obtained from natural samples, including aerialplant parts, rhizosphere and bare soil in agricultural and land environments from the Northeasternpart of Spain, were characterized for the presence of the antimicrobial peptidebiosynthetic genes srfAA (surfactin), bacA (bacyllisin), fenD (fengycin), bmyB (bacyllomicin),spaS (subtilin) and ituC (iturin). Most isolates had at least one of the biosynthetic genes andpresented 2-to-4 genes simultaneously. The most frequent genotypes were srfAA bacA bmyB(15.2%) and srfAA bacA bmyB fenD (14.1%). The analysis of in vitro antagonism against eightspecies of plant-pathogenic bacteria indicated that the proportion of highly active antibacterialstrains increased with the number of simultaneous genes per strain.