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.

近年来，作为新型的环境友好型破乳剂，生物破乳剂受到了特别的关注。本研究报道了一种由莫来芽孢杆菌XH1分泌的新型生物破乳草酸脱羧酶（OxdC）。全基因组比较表明，破乳效率高的菌株均具有烷烃降解基因。对不同底物诱导的差异表达基因和蛋白质的分析表明，XH1分泌的OxdC是有效的破乳剂。此外，破乳能力通过原核基因表达，敲除和互补分析得到证实。XH1的OxdC表现出强大的破乳能力，并且明显优于模型蛋白枯草芽孢杆菌168 OxdC（Yvrk），具有很高的氨基酸相似性，但破乳能力有限。通过比较结构特征，确定OxdC表面的疏水氨基酸是驱动XH1良好破乳活性的关键因素。XH1的代谢途径以液体石蜡和葡萄糖为底物，说明碳氢化合物是生物破乳剂分泌所必需的。本研究提供了新的见解，OxdC作为生物破乳中额外的遗传资源的应用。