羊肠道蒙氏肠球菌和屎肠球菌的分离鉴定及益生特性分析

Isolation and identification of Enterococcus mundtii and Enterococcus faecium with probiotic properties from the intestine of sheep

摘要:

【背景】随着病原菌对抗生素耐药性的不断增加，在畜牧业养殖中研发安全可靠的抗生素替代品变得越来越重要。益生菌以其无毒、无残留、低成本且能有效补充肠道有益微生物等诸多优点，成为一种理想的抗生素替代品。【目的】从绵羊肠道共生菌中分离获得满足益生特性的益生菌。【方法】将健康绵羊肠道内容物及粪便在MRS培养基上分离纯化，利用形态学和16S rRNA基因序列分析鉴定分离菌株；通过抗菌活性分析、耐酸和耐胆盐能力测定、自聚集能力测定、抗生素敏感性分析及对小鼠的安全性测定等确定益生特性。【结果】从健康绵羊肠道中分离出多株肠道共生菌，经鉴定其中2株属于肠球菌，分别为蒙氏肠球菌(Enterococcus mundtii) A12和屎肠球菌(Enterococcus faecium) C1。抗菌分析显示，分离菌株A12和C1培养上清对金黄色葡萄球菌(Staphylococcus aureus)和猪霍乱沙门氏菌(Salmonella choleraesuis)均有很强的抗菌活性。耐受性分析显示分离菌株A12和C1具有良好的耐酸和耐胆盐特性，并且均具有很强的自聚集能力。药敏试验发现分离菌株A12和C1对多种抗生素敏感。小鼠体内安全性试验显示分离菌株A12和C1未使小鼠出现明显的病理变化，因此具备良好的安全性。【结论】分离纯化的2株肠道共生菌Enterococcus mundtii A12和Enterococcus faecium C1具有优良的益生特性和良好的安全性，具备作为益生菌开发的潜力。

关键词:羊肠道;分离纯化;肠球菌;益生特性

Abstract:

[Background] As the resistance of pathogens to antibiotics is enhancing, it is increasingly important to develop safe and reliable antibiotic alternatives in the animal husbandry. Probiotics with no toxicity, no residues, and low costs have emerged as potential solutions, offering effective supplements of beneficial microorganisms in the intestinal tract. [Objective] To isolate probiotics from the intestine of sheep. [Methods] The intestinal contents and feces of healthy sheep were cultured and purified with the MRS medium, and the isolates were then identified by morphological analysis and 16S rRNA gene sequencing. The probiotic properties of the isolates were assessed, including the antimicrobial activity, acid and bile salt tolerance, self-aggregation capacity, antibiotic sensitivity, and safety in mice. [Results] Several strains were isolated from the intestine of healthy sheep, among which A12 and C1 were identified as Enterococcus mundtii and E. faecium, respectively. The cell-free supernatants of isolates A12 and C1 had strong inhibitory activities against Staphylococcus aureus and Salmonella choleraesuis. The isolates A12 and C1 had good acid and bile salt tolerance and strong self-aggregation ability and were susceptible to a variety of antibiotics. In addition, the two isolates did not induce obvious pathological lesions in mice, demonstrating good safety. [Conclusion] E. mundtii strain A12 and E. faecium strain C1 isolated from the sheep intestine have excellent probiotic properties and good safety, showcasing the potential to be developed as probiotics.

Key words:sheep intestine;isolation and purification;Enterococcus sp.;probiotic properties