Biological control of Fusarium foot rot of wheat using fengycin-producing Bacillus subtilis isolated from salty soil

Abstract

Bacillus species are well known for their ability to control plant diseases through various mechanisms, including the production of secondary metabolites. Bacillus subtilis SR146 isolated from Tunisian salty soil showed in vitro activity against several species of Fusarium including Fusarium culmorum, Fusarium graminearum, Fusarium oxysporum, Fusarium melonis, Fusarium equiseti and Fusarium solani.Moreover, wheat seeds treated with SR146 strain was effective in controlling foot rot disease in wheat caused by F. culmorum under a glasshouse assay. The bacterial strain SR146 markedly increased the plant seedling emergence in comparison to the non-infested experimental series. Complete inhibition of F. culmorum spores germination by the strain SR146 was also observed. The highest levels of antifungal metabolites produced by B. subtilis SR146 were detected during bacterial stationary growth phase. The compounds which are responsible for antifungal activity were purified and characterized. Identification by mass spectrometry showed high similarity to fengycin, this result was confirmed by polymerase chain reaction (PCR) detection of the fenA gene of the fengycin operon. Key words: Bacillus subtilis, foot rot, Fusarium culmorum, fengycin, Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS),polymerase chain reaction detection.