Soft rot is the most serious bacterial disease causing rot loss of postharvest pepper during storage and transportation. In order to reduce the loss of pepper caused by soft rot, pathogen was isolated from rotten pepper and antagonist was screened to control the soft rot caused by this pathogen. The result showed that the pathogen XC1 isolated from rotten pepper was Pecobacterium carotovorum subsp. brasiliense (Pcb). Pcb XC1 had strong pathogenicity, with concentrations of 104 CFU/mL and above, it could cause 100% rot of pepper within 3 days at room temperature (25 ℃). Furthermore, an antagonistic strain 1151 was screened by double-layer agar plate method, which was identified to be Bacillus subtilis by 16S rDNA. In vitro antibacterial result showed that cells and antimicrobial peptide of B. subtilis 1151 had inhibitory activity against Pcb XC1. In vivo result of pepper disease control showed that cells and antimicrobial peptide of B. subtilis 1151 could reduce the rotting rate of pepper and its lesion diameter, among which antimicrobial peptide performed better. The antimicrobial peptide could reduce the number of Pcb XC1 in pepper by 99%. The result of scanning electron microscope also showed that the soft rot symptom of pepper surface treated by antimicrobial peptide was less, and there were no obvious folds and debris caused by cell wall degradation. On one hand, from the protein level, 3 antimicrobial peptides were identified by LC-MS/MS which were BHP, SP-B and Hb 98-114. On the other hand, from the gene level, a bacteriocin gene cluster was identified from the genome of B. subtilis 1151 by BAGEL4 database, containing two bacteriocins Subtilisin A and Subtilisin Sbox. This study showed that B. subtilis 1151 could reduce the rot loss of pepper caused by soft rot, and its antimicrobial peptides played an important role. It has important reference significance for the storage and preservation method of postharvest pepper.
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