Biocontrol and plant stimulating potential of novel strain Bacillus sp. PPM3 isolated from marine sediment

Abstract

In the current study, the biocontrol potential of a novel strain Bacillus sp. PPM3 isolated from marine sediment from the Red Sea in Hurghada, Egypt is recognized. This novel strain was selected out of 32 isolates based on its ability to suppress the growth of four plant pathogenic fungi: Aspergillus flavus, Fusarium graminearum, Mucor sp. and Alternaria sp. The new marine strain was identified and characterized by phenotypic and molecular approaches. The culture filtrate of Bacillus sp. PPM3 suppressed the growth and spore germination of all tested fungi in vitro with the highest value of inhibition reported for Mucor sp. (97.5%). The antifungal effect of the culture filtrate from the strain PPM3 was due to production of highly stable secondary metabolites resistant to extreme pH, temperature and enzymatic treatments. A PCR analysis confirmed the expression of genes involved in the synthesis of antifungal lipopeptides: iturin, bacillomycin D, mycosubtilin and surfactin. In a greenhouse experiment strain PPM3 effectively reduced disease incidence of F. graminearum in maize plants and displayed additional plant growth stimulating effect. The results show that novel marine strain PPM3 could have a potential in commercial application as biocontrol agent for treatment of various plant diseases caused by soil-borne and postharvest pathogenic fungi.