Abstract：
This study investigated the safety characteristics and potential probiotic properties of Enterococcus faecium by using whole genome analysis, and then explored the effect of this strain on the virulence of Listeria monocytogenes in vitro and during the storage of fermented sausages. Results showed that E. faecium B1 presented enterocin A, B, and P, enterolysin A, and UviB, and the exotoxin related genes and exoenzyme related genes were not detected in the genome of E. faecium B1. However, the adherence genes including acm and scm were present in this strain, which also positively correlated with characteristics related to probiotic potential. In addition, E. faecium could adapt to the condition of fermented sausages, and decrease the survival of L. monocytogenes in vitro and in vivo. The expression of the virulence genes (prfA, hly, inlA, and inlB) and sigB-related genes (prli42, rsbT, rsbU, rsbV, rsbW, and sigB) were all inhibited by E. faecium B1 to different extents during the storage of fermented sausages at 4 °C. Moreover, compared with the E. faecium B1 group, the expression level of entA, entB, and entP genes of E. faecium B1 in the co-culture of fermented sausages was increased during the storage, which may be the inhibition mechanism of E. faecium B1 on L. monocytogenes. These results demonstrated that E. faecium B1 could potentially be used as bio-protection to control L. monocytogenes in meat products.
摘要：
本研究通过全基因组分析研究了屎肠球菌的安全性特征和潜在的益生菌特性。然后探讨了该菌株在发酵香肠的体外和贮藏过程中对单核细胞增生李斯特菌毒力的影响。结果表明，屎肠球菌B1呈现肠霉素A，B,P,肠溶素A,和UviB,在屎肠球菌B1基因组中未检测到外毒素相关基因和外切酶相关基因。然而,该菌株中存在包括acm和scm在内的粘附基因，这也与益生菌潜力相关的特征呈正相关。此外,屎肠球菌能适应发酵香肠的条件，并降低单核细胞增生李斯特菌在体外和体内的存活率。毒力基因的表达(prfA，hly,inla,和inlB)和sigB相关基因(prli42，rsbT，RSBU,RSBV,RSBW,和sigB)在4℃发酵香肠的贮藏过程中都受到屎肠球菌B1不同程度的抑制。此外，与屎肠球菌B1组相比，entA的表达水平，entB,发酵香肠共培养中屎肠杆菌B1的entP基因在贮藏过程中增加，这可能是屎肠球菌B1对单核细胞增生李斯特菌的抑制机制。这些结果表明屎肠球菌B1可以潜在地用作生物保护以控制肉制品中的单核细胞增生李斯特菌。
