Postharvest Biological Control of Colletotrichum acutatum on Apple by Bacillus subtilis HM1 and the Structural Identification of Antagonists

Abstract

Bacillus subtilis HM1 was isolated from the rhizosphere region of halophytes for its antifungal activity against Colletotrichum acutatum, the causative agent of anthracnose. Treatment of postharvest apples with the cell culture or with a cell-free culture supernatant reduced disease severity 80.7% and 69.4%, respectively. Both treatments also exhibited antifungal activity against various phytopathogenic fungi in vitro. The antifungal substances were purified and analyzed by acid precipitation, gel filtration, high-performance liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Three compounds were identified as fengycin, iturin, and surfactin. The MALDI-TOF/ TOF mass spectrum revealed the presence of cyclized fengycin homologs A and B, which were distinguishable on the basis of the presence of either alanine or valine, respectively, at position 6 of the peptide sequence. In addition, the cyclized structure of fengycin was shown to play a critical role in antifungal activity.

Co-culturing of Fungal Strains Against Botrytis cinerea as a Model for the Induction of Chemical Diversity and Therapeutic Agents

“…Fungal co-culturing techniques have been used previously to mimic in vitro microbial interactions occurring in their natural environment and to identify new antifungal compounds ( Liu et al, 2001 ; Kim et al, 2015 ; Lopes et al, 2015 ; Ting and Jioe, 2016 ). We selected B. cinerea as a model to be used in fungal co-cultures and to induce the production of new SMs derived from fungal interactions.…”

Effects of rhizobacteria Paenibacillus polymyxa APEC136 and Bacillus subtilis APEC170 on biocontrol of postharvest pathogens of apple fruits

“…in biocontrol activity (Kong et al, 2012;Zhang et al, 2013). Recently, Kim et al (2015) reported that treating harvested apples with B. subtilis suspensions yielded a greater reduction in disease severity caused by C. acutatum than that with the culture filtrate. The isolates APEC136 and APEC170 greatly reduced the growths of C. gloeosporioides and C. acutatum pathogens in vitro, probably owing to their production of antifungal compounds.…”

Characterization and evaluation of Bacillus subtilis GYUN-2311 as a biocontrol agent against Colletotrichum spp. on apple and hot pepper in Korea

“…Our study has investigated the efficacy of B. subtilis as a biocontrol agent targeting Colletotrichum species, highly destructive pathogens affecting various crops, including hot peppers and apples. B. subtilis has been shown to reduce anthracnose infections caused by C. gloeosporioides in red peppers ( Lee et al, 2020 ) and C. acutatum in apples ( Kim et al, 2015 ). Furthermore, a number of B. subtilis strains have been documented to impede the development of diverse fungal pathogens at varying degrees.…”