Isolation and anti-Verticillium dahliae activity from Bacillus axarquiensis TUBP1 protein

Abstract

Anti-Verticillium dahliae proteins were purified by applying (NH4)2SO4 (70%) precipitation, DEAE Sepharose Fast Flow (DEAE FF), and Sephadex G-100 column chromatography to analyze the anti-V. dahliae proteins produced by Bacillus axarquiensis TUBP1. The anti-V. dahliae fraction was identified by using LC–MS/MS. The relative molecular mass and isoelectric point (pI) of purified anti-V. dahliae protein were 6.22kDa and 4.82, respectively. We obtained the amino acid sequences of four peptide segments, among them, two novels, whereas the other two were similar to peptidase T(tr154685475). Our results showed that the anti-V. dahliae protein from B. axarquiensis TUBP1 possessed good thermal stability, and that an alkaline condition was conducive for the anti-V. dahliae activity of purified proteins. Scanning electron microscopy (SEM) experiments showed that protein-treated V. dahliae exhibited anomalies in the morphology of the fungal hyphae and spores. Transmission electron microscopy (TEM) experiments suggested that the plasma membrane of V. dahliae may be main target of the antifungal protein from B. axarquiensis TUBP1. The strong anti-V. dahliae activity of B. axarquiensis TUBP1 implied that its components might provide an alternative source of the biocontrol of Verticillium wilt.