a b s t r a c t
Two strains of Bacillus sp., SS-12.6 and SS-13.1, showed very strong antibacterial and antifungal activity
against phytopathogens. The PCR analysis showed that both strains have the genes for biosynthesis of iturin,
bacillomycin and surfactin. Kinetics of production of antimicrobial substances in these strains
showed that synthesis started at the beginning of exponential phase of growth. Maximum of activity
was slowly reached at the beginning of stationary growth phase and was maintained until the end of
observed period. Ethyl acetate extracts of cell-free supernatants of both strains were particularly active
against several postharvest fungal pathogens, in vitro and in vivo, in the experiment with apple fruits.
Mass spectrometry analysis of ethyl acetate extract of the supernatant of strain SS-12.6 confirmed the
presence of antimicrobial lipopeptide surfactin.