Two novel cationic antifungal peptides isolated from Bacillus pumilus HN-10 and their inhibitory activity against Trichothecium roseum

Public concern for food safety and environmental issues and the increase in fungicide-resistant pathogen have enhanced the interest in developing alternative methods to fungicides to control postharvest fruit decay. In this study, a bacterial strain isolated from stale potato vermicelli was identified as Bacillus pumilus HN-10 based on morphological characteristics and 16S rRNA gene sequence analysis. Furthermore, two novel cationic antifungal peptides named P-1 and P-2 were purified from B. pumilus HN-10 using macroporous adsorbent resin AB-8, Sephadex G-100 chromatography, and reversed-phase high-performance liquid chromatography. The primary structure of P-1 and P-2, which were proved to be novel antifungal peptides by BLAST search in NCBI database, was PLSSPATLNSR and GGSGGGSSGGSIGGR with a molecular weight of 1142.28 and 1149.14 Da, respectively, as indicated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Both P-1 and P-2 exhibited strong antifungal activity against Trichothecium roseum with minimum inhibitory concentrations starting from 1 mu g/mL. The two novel antifungal peptides were stable below 80 degrees C for 2 h, but lost their activity in 15 min at 121 degrees C. In addition, they were resistant to the proteolytic action of pepsin, trypsin, and papain, and stable within a wide range of pH (2.0-12.0). These results showed that P-1 and P-2 are novel cationic antifungal peptides with specific activity against T. roseum.