Investigation of the Antifungal Activity of Bacillus megaterium Against Fusarium Species

Abstract

Several Fusarium species are emerging as serious pathogens on small grain cereals worldwide. The use of fungicides is a short-term strategy in the fight against Fusarium diseases. The use of biocontrol agents is an attractive alternative strategy by reducing the chemical input to the environment as well as being economical. Bacillus species have received attention as biocontrol agents. In this study, the antagonistic activities of Bacillus megaterium CTBmeg1 and HMA5 strains on Fusarium culmorum UK99 and F. graminearum PH-1 isolates were investigated in vitro and at molecular level. On the 7th day of the dual culture assay, both of B. megaterium strains significantly reduced the mycelial growth of Fusarium isolates, with very high antifungal activity with the inhibition rate between 72.7% and 77.7%, respectively. Similarly, both strains caused high antifungal activity in the volatile organic compound (VOC) analysis between 52.1% and 62.4%, respectively. At the molecular level, in all tested groups, transcript levels of the tri5 gene, which is associated with trichothecene production, decreased, while the transcript levels of cat, an antioxidant gene, and mst20, a gene related to apoptosis, increased. Findings from this study showed that B. megaterium CTBmeg1 and HMA5 strains could be accepted as highly effective biocontrol agents against worldwide phytopathogens F. culmorum and F. graminearum.