Yeasts and Bacillus spp. as potential biocontrol agents of Sclerotinia sclerotiorum in garlic

Abstract

This study aimed to detect potential bacteria and yeast for prevention of Sclerotinia sclerotiorum infection via biocontrol in garlic. Two yeasts (Pichia kudriavzeviiand Candida labiduridarum) and four bacteria (Bacillus acidiceler, B. macauenses, B. amyloliquefaciens and B. pumilus) were tested. The effect of volatile and diffusible antifungal metabolites on S. sclerotiorum mycelial growth in vitro was evaluated. Garlic cloves were immersed in a suspension of each microorganism (1 × 108 cells ml−1), then the phytopathogen was inoculated and the cloves were kept in a moist chamber for 15 days, at which point lesion diameter was evaluated and electron micrographs were obtained. The results showed a higher percentage of inhibition of S. sclerotiorum growth by volatile metabolites produced by C. labiduridarum, B. macauenses, B. amyloliquefaciensand B. pumilus than by those produced by the other agents, with variation of 74.61%–87.61%. A high reduction in phytopathogen growth due to B. amyloliquefaciens(84%) was observed, suggesting that B. amyloliquefaciens produces antifungal metabolites that inhibit phytopathogen development. The reduction in disease-affected area was most significant in garlic cloves treated with B. pumilus (86.74%) and C. labiduridarum (61.47%). Electron micrographs showed garlic clove surface colonization by all tested microorganisms and phytopathogen hyphae colonization. Research on B. amyloliquefaciens, B. pumilus and C. labiduridarum biocontrol of S. sclerotiorum in garlic is of interest.