Identification of an Antifungal Bacillus Strain and Studies on Its Antifungal Active Ingredients

Abstract

Strain NK-2 which has broad spectrum of antifungal activity against eight kinds of phytopathogenic fungi was identified as Bacillus amyloliquefaciens by analysis of partial 16S rDNA, gyrA gene, and rpoB gene sequences. The crude protein, obtained from NK-2 culture, exhibited inhibitory activity on mycelial growth and conidial spore germination of Fusarium oxysporum. The crude proteins were further purified by Sephadex G-200 and the antifungal fraction was checked by SDS-PAGE. The putative active protein was then analyzed by Tandem mass spectrum. The result revealed that the target protein was high similar to protein YhfE from B. amyloliquefaciens FZB 42. Then we cloned the yhfE (GenBank accession:HM143898) from NK-2 genome and expressed it in Escherichia coli BL21. The purified recombinant YhfE protein could also inhibit the spore germination and mycelial growth of F. oxysporum. We have found for the first time, to our knowledge, that YhfE has antifungal activity.