Isolation and identification of Bacillus mojavensis YL-RY0310 and its biocontrol potential against Penicillium expansum and patulin in apples

Penicillium expansum is the main causal organism of apple rot and causes huge economic losses during apple storage. Patulin (PAT) produced by P. expansum, occurs widely in apples and their products because of its water-solubility and thermal stability. In the present study, we isolated bacterial strains with antagonistic activity against P. expansum to effectively control the growth of P. expansum and production of PAT. We isolated a bacterium named YL-RY0310, which inhibited the growth of P. expansum and production of PAT in apples by 77.4% and 48.4%, respectively. Strain YL-RY0310 was 96% homologous to Bacillus mojavensis using morphological and 16S rRNA gene sequencing analyses. In addition, DNA amplification analysis using Bacillus-specific primers showed that the genes responsible for synthesis of lipopeptides of surfactin, iturins and fengycin are expressed. Oxford cup agar diffusion test showed that its crude lipopeptides could effectively inhibit the growth of P. expansum. Furthermore, strain YL-RY0310 could significantly degrade PAT; the degradation efficiencies of the intracellular and extracellular metabolites of the strain were 62.6% and 56.9%, respectively. Therefore, B. mojavensis YL-RY0310 could be used as a biocontrol agent to inhibit the growth of P. expansum and control PAT contamination in apples. This study provides a theoretical basis for a novel biological control strategy and degradation of mycotoxin.