Wan Xing, Saris Per E J, Takala Timo M
Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 56, Helsinki, Finland.
Res Microbiol. 2015 Jul-Aug;166(6):494-503. doi: 10.1016/j.resmic.2015.04.003. Epub 2015 May 6.
Leuconostoc carnosum 4010 is an antimicrobial strain used as a protective culture in vacuum-packed meats. In this study, we showed that, in addition to antilisterial class IIa bacteriocins leucocin A and C, the strain also produces class IId bacteriocin leucocin B, the antimicrobial activity of which is limited to the genera Leuconostoc and Weissella. Two novel genes, lebBI encoding the leucocin B precursor with a double-glycine-type leader and putative immunity protein LebI, were identified on L. carnosum 4010 plasmid pLC4010-1. LebI contains three transmembrane spans and shares 55% identity with the mesentericin B105 immunity protein. Genes lebBI were shown to be transcribed in 4010 by RT-PCR analysis. The secretion of leucocin B in L. carnosum 4010 was shown by spot-on-lawn and SDS-gel overlay methods with a Leuconostoc strain sensitive to leucocin B but resistant to leucocins A and C. In addition, leucocins A and B from L. carnosum 4010 were cloned as SSusp45 fusions in heterologous host Lactococcus lactis and the secretion of active bacteriocins was detected on indicator plates.
肉酒球菌4010是一种抗菌菌株，用作真空包装肉类中的保护培养物。在本研究中，我们发现，除了抗李斯特菌的IIa类细菌素亮菌素A和C外，该菌株还产生IId类细菌素亮菌素B，其抗菌活性仅限于肉酒球菌属和魏斯氏菌属。在肉酒球菌4010质粒pLC4010-1上鉴定出两个新基因，即编码具有双甘氨酸型前导肽的亮菌素B前体的lebBI和推定的免疫蛋白LebI。LebI含有三个跨膜结构域，与肠膜明串珠菌素B105免疫蛋白具有55%的同一性。通过RT-PCR分析表明，lebBI基因在4010中可转录。采用点样法和SDS凝胶覆盖法，以对亮菌素B敏感但对亮菌素A和C耐药肉酒球菌菌株，证实了肉酒球菌4010中亮菌素B的分泌。此外，将肉酒球菌4010的亮菌素A和B作为SSusp45融合体克隆到异源宿主乳酸乳球菌中，并在指示平板上检测到活性细菌素的分泌。
