The plant-associated Bacillus amyloliquefaciens strains MEP218 and ARP23 capable of producing the cyclic lipopeptides iturin or surfactin and fengycin are effective in biocontrol of sclerotinia stem rot disease

ALVAREZ F.; CASTRO M.; PRÍNCIPE A.; BORIOLI G.; FISCHER S.; MORI G.; JOFRÉ E.

JOURNAL OF APPLIED MICROBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 p. 159 - 174

1364-5072

Aims: This work was conducted to identify the antifungal compounds producedby two previously isolated Bacillus sp. strains: ARP23 and MEP218. Bothstrains were subjected to further analysis to determine their taxonomic positionand to identify the compounds responsible for their antifungal activity as wellas to evaluate the efficiency of these strains to control sclerotinia stem rot insoybean.Methods and Results: The antifungal compounds were isolated by acid precipitationof cell-free supernatants, purified by RP-HPLC and then tested forantagonistic activity against Sclerotinia sclerotiorum. Mass spectra from RPHPLCeluted fractions showed the presence of surfactin C15, fengycins A (C16?C17) and B (C16) isoforms in supernatants from strain ARP23 cultures, whereas the major lipopeptide produced by strain MEP218 was iturin A C15. Alterations in mycelial morphology and sclerotial germination were observed in the presence of lipopeptides-containing supernatants from Bacillus strains cultures. Foliar application of Bacillus amyloliquefaciens strains on soybean plants prior to S. sclerotiorum infection resulted in significant protection against sclerotinia stem rot compared with noninoculated plants or plants inoculatedwith a nonlipopeptide-producing B. subtilis strain.Conclusions: Both strains, renamed as B. amyloliquefaciens ARP23 andMEP218, were able to produce antifungal compounds belonging to the cyclic lipopeptide family. Our data suggest that the foliar application of lipopeptide producing B. amyloliquefaciens strains could be a promising strategy for the management of sclerotinia stem rot in soybean.Significance and Impact of the Study: Sclerotinia stem rot was ranked as oneof the most severe soybean disease in Argentina and worldwide. The results ofthis study showed the potential of B. amyloliquefaciens strains ARP23 andMEP218 to control plant diseases caused by S. sclerotiorum.