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.
Ning Hou,Qiaoruo Wang,Yang Sun,Xianyue Li,Qiuying Song,Xinxin Jiang,Baoxin Li,Xinyue Zhao,Hailian Zang,Dapeng Li,Chunyan Li
In recent years, special attention has been devoted to biodemulsifiers as a new type of environment-friendly demulsifiers. A novel biodemulsifying oxalate decarboxylase (OxdC) secreted by Bacillus mojavensis XH1 is reported in the present study. A genome-wide comparison showed that strains with high demulsification efficiencies all possess alkane degradation genes. An analysis of the differentially expressed genes and proteins induced by different substrates showed that OxdC secreted by XH1 was an effective demulsifier. Moreover, the demulsification ability was verified by prokaryotic gene expression, knockout and complementation analyses. OxdC from XH1 exhibited a strong demulsification capacity and significantly outperformed the model protein Bacillus subtilis 168 OxdC (Yvrk), which shared a high amino acid similarity but showed limited demulsification ability. Based on a comparison of the structural characteristics, the hydrophobic amino acids on the surface of OxdC were identified as a key factor driving the favorable demulsification activity of XH1. The metabolic pathways of XH1 used liquid paraffin and glucose as substrates, illustrating that hydrocarbons are necessary for biodemulsifier secretion. The present study provides new insight into the application of OxdC as an additional genetic resource in biodemulsification.
危险品化学品经营许可证（带存储）