Analysis of the bacteriocins of vancomycin-resistant Enterococcus faecium (VRE) clinical isolates

对从密歇根大学医学院医院获得的总共636株VRE分离株进行细菌素生产测试。277株（44%）为细菌素原性菌株。从菌株VRE 200和VRE 82中分别分离到两个细菌素质粒pTI 1（12.5kb）和pDT 1（6.2kb）。pTI 1编码的细菌素32（Bac32）具有抗屎肠球菌、大肠杆菌和大肠杆菌的活性。hidelians和E.硬脑膜。pDT 1编码细菌素43（Bac 43），其对粪肠球菌（E.faecalis）、屎肠球菌（E.faecium）、肠球菌（E.historium）、持久肠球菌（E.durance）和单核细胞增生李斯特菌（Listeria monocytogenes）具有活性。Bact32基因由细菌素基因巴卡和免疫基因bacB组成。推导出的巴卡A蛋白全长89个氨基酸，N端含有19个氨基酸的信号肽。Bac 32与任何已知的细菌素决定簇均无同源性。Bac 43基因由细菌素基因巴卡A和免疫基因bacB组成。推导的Bac 43的巴卡A产物长度为74个氨基酸，N端含有30个氨基酸的信号肽。Bac 43与乳酸菌膜活性IIa类细菌素具有较高的同源性。Southern杂交和PCR扩增结果表明，277株细菌素产生菌中分别有137株（49.5%）和22株（7.9%）携带bac 32基因和bac 43基因。

A total of 636 VRE isolates obtained from the Medical School Hospital of the University of Michigan were tested for bacteriocin production. Two hundred seventy-seven (44%) of the strains were bacteriocinogenic. Two bacteriocin plasmids pTI1(12.5 kb) and pDT1 (6.2 kb) were isolated from the strains VRE200 and VRE82, respectively. pTI1 encoded bacteriocin 32 (Bac 32) active against E.faecium, E. hirae and E. durans. pDT1 encoded bacteriocin 43 (Bac 43) active against E.faecalis, E.faecium, E.hirae, E.durance and Listeria monocytogenes. Bact 32 gene consists of the bacteriocin gene bacA and the immunity gene bacB. The deduced bacA product is 89 amino acids in length, with a putative signal peptide of 19 amino acids at the N terminus. Bac 32 showed no homology to any known bacteriocin determinant. Bac 43 gene consists of the bacteriocin gene bacA and the immunity gene bacB. The deduced bacA product of Bac 43 is 74 amino acids in length with putative signal peptide of 30 amino acids at the N terminus. Bac 43 showed the high homologies with the membrane-active class IIa bacteriocins of lactic acid bacteria. Southern analyses and PCR amplification analyses showed that among the 277 bacteriocinogenic strains 137 isolates (49.5 %) carried the bac 32 gene and 22 isolates (7.9 %) carried the bac 43 gene, respectively.