Characterization and Inhibitory Effects of an Antifungal Protein from the Bacillus cereus Strain YN917

Abstract

In this research, a type of antifungal protein derived from the Bacillus cereus strain YN917, was precipitated by ammonium sulfate after fermentation. We investigated the antifungal effects and antifungal mechanism of the protein as well as its stability under different stress conditions such as the variation of temperature, pH value, exposure to ultraviolet radiation and proteases. Furthermore, the in vitro needle inoculation method was carried out to explore the antagonistic effects of 40% isoprothiolane Wettable powder (WP), 20% tricyclazole WP and the YN917 antifungal protein against the rice blast pathogen, Magnaporthe oryzae. Results showed that 20% tricyclazole WP and 40% isoprothiolane EC treatments had significant antagonistic effects on rice blast, and that the YN917 protein also had a dual inhibitory effect on mycelium growth and conidiospore germination in M. oryzae, which can cause this mycelium to swell and twist. The YN917 protein had a broad inhibitory spectrum with different effects on 15 plant- associated pathogenic fungi and oomycetes, such as Botrytis cinerea, Bipolaris maydis and M. oryzae. In addition, the physical and chemical properties of this antifungal protein were relatively stable and have potential for application in the biocontrol of fungal pathogens in plants. Overall, the results revealed that this protein has a wide tolerance to different temperatures, pH values, exposures to ultraviolet radiation and proteases, which is required for it to function as a bio-control agent against rice blast under a wide range of environmental conditions. © 2021 Friends Science Publishers