替代抗生素益生菌的筛选及其抗鸡沙门氏菌感染的研究. (Chinese)

In this study, we aim to screen out the probiotics that can replace antibiotics and evaluate their application effect against Salmonella infection through several steps. Firstly, the agar-plate method was used to the candidate strains with strong antibacterial activity from 15 candidate probiotics with standard pathogenic Escherichia coli, Salmonella pullorum and Staphylococcus aureus as indicator bacteriat. Then 10 clinically isolated pathogenic bacteria were used as indicator bacteria, and the most active probiotics were selected from the above 5 candidate probiotics by agar-plate method. The screening results showed that there were 5 strains of probiotics with strong antibacterial activity, i.e. L.C332, E.C329, L.C314, L.C311 and L.C308, among which L.C32 strain of Lactobacillus salivus had the strongest antibacterial activity. Then, it was applied to animal experiments against Salmonella infection. SPF chickens were randomly divided into 3 groups. The probiotic group which is the first group was fed with 1×10 9 cfu of L. C332 per chicken daily and were orally infected with 1 × 10 4 cfu of Salmonella pullorum C79- 1 per day. The second group is the infection control group which was orally infected with 1×10 4 cfu Salmonella pullorum C79-1 per chicken every day. The last blank control group was fed basal diet. After infection, blood samples were collected weekly to detect the pullorum antibody titer by the plate agglutination method. Four weeks later, all chichens were forced to kill and their liver and intestinal contents were collected. The bacteria of Salmonella in liver and intestinal tract of chickens in each group were cultured with Salmonella chromogenetic medium and counted by colony count. The results have shown that the positive rate of antibodies in the probiotic group was only 10%, and the positive rate of antibodies in the infection control group was 80% . The content of Salmonella bacteria in the liver of the probiotic group was significantly lower than that of the infection control group (P<0.001). The contents of Salmonella in the duodenum, jejunum, ileum and cecum of the probiotic group were extremely significantly lower than those in the infected control group (P<0.0001, P<0.001, P< 0.001, P<0.01). These results indicated that Lactobacillus salivarius L.C332 could effectively inhibit the colonization of Salmonella dysentery in chicken liver and intestinal tract and prevent its natural infection, and L.C332 also had strong antibacterial activity in vitro and in vivo. This study provides reference for the screening and application of novel alternative antibiotic probiotics. [ABSTRACT FROM AUTHOR]

为筛选能够替代抗生素的益生菌并评估其抗鸡沙门氏菌感染的应用效果, 本研究先通过琼脂平板法以 标准致病性大肠埃希氏菌、鸡白痢沙门氏菌及金黄色葡萄球菌作为指示菌, 从15株候选益生菌中筛选具有较强抗菌 活性的候选菌株; 再以临床分离的 10 株致病菌为指示菌, 通过琼脂平板法从上述 5 株候选益生菌中筛选抗菌 活性最强的益生菌。筛选结果显示, 有 5 株益生菌的抗菌活性较强, 分别为 L.C332、E.C329、L.C314、L.C311、 L.C308, 其中唾液乳杆菌 L.C332 株的抗菌活性最强。将 SPF 鸡随机分为 3 组, 益生菌组鸡每日饲喂 1×109 cfu 的 L.C332株, 同时每日口服感染1×104 cfu的鸡白痢沙门菌C79-1株; 感染对照组鸡每日口服感染1×104 cfu鸡白痢沙门 菌C79-1株; 空白对照（BC）组鸡饲喂基础日粮。感染后每周采血通过平板凝集法检测血清中的鸡白痢抗体效价, 4 周后剖杀全部鸡, 取其肝脏及各肠道内容物, 采用沙门氏菌显色培养基培养并经菌落计数统计各组鸡肝脏及肠道中 的沙门氏菌属细菌。结果显示：益生菌组鸡抗体阳性率仅10%, 感染对照组鸡抗体阳性率达80%; 益生菌组鸡肝 脏、十二指肠、空肠、回肠及盲肠中的沙门氏菌属细菌含量虽均高于 BC 组鸡但均极显著低于感染对照组鸡 （P<0.001）。上述结果表明, 口服唾液乳杆菌L.C332可以有效抑制鸡白痢沙门菌在鸡肝脏及肠道中的定植, 阻止其自 然感染, 且 L.C332株在体内外均具有较强的抑菌活性。本研究为新型替代抗生素益生菌的筛选和应用提供参考依据。 [ABSTRACT FROM AUTHOR]

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