一株屎肠球菌的益生特性及安全性研究

发布时间：2018-07-10 06:58

  本文选题：益生菌 + 屎肠球菌　； 参考：《山东农业大学》2017年硕士论文

【摘要】：益生菌作为一种饲料添加剂,在畜牧业生产中得到越来越广泛的应用,其饲喂效果也得到了畜牧从业者和学者的广泛认可。但益生菌的益生特性表现出较为明显的菌株差异,因此要得到益生性能优良的益生菌株,就要进行大量的筛选工作。实验室前期分离保存了一株具有高胆盐耐受特性的益生菌,本课题对该株益生菌的种属、益生特性及安全性进行了系统的研究。具体研究内容及结果如下:(1)通过形态学观察、生化鉴定及16S rDNA序列比对分析,确定该菌株为屎肠球菌(Enterococcus faecium),并命名为屎肠球菌SQ-1。(2)对该株菌开展了体外益生特性研究,实验结果表明:SQ-1具有较好的耐酸、耐胆盐、耐高温、耐消化酶等特性。在p H2.0的条件下培养3h仍有61.93%的存活率;在胆盐浓度为0.3%的条件下培养3h有90.37%的存活率,胆盐浓度达0.6%时仍有49.7%的存活率;在60℃环境中处理15min仍有77.66%的存活率;经过1.2%的胰蛋白酶处理3h后有31.01%的存活率。这些实验结果表明该株菌具有较好的抗逆性,且对高浓度胆盐的耐受性较为突出。采用碳氢化合物黏着法检测该菌的疏水性,结果表明SQ-1疏水率为34.53%,具有中等疏水性。在对沙门氏菌(CVCC 3377)和金黄色葡萄球菌(CICC23926)的抑菌实验中,抑菌圈直径分别为11mm和13mm,具有中等抑菌作用。(3)进行了SQ-1对小鼠单核-巨噬细胞吞噬功能和血清中IgG、IL-2含量影响的研究。碳粒廓清实验结果表明,口服1×109cfu/mL的屎肠球菌SQ-1组与对照组比较,廓清指数出现显著性(P0.05)升高,表明该菌株对小鼠的吞噬功能具有显著的增强作用;血清中IgG含量检测结果显示,口服1×109cfu/mL的屎肠球菌SQ-1组与对照组相比较,IgG含量有极显著性(P0.01)升高;而IL-2含量无显著性差异。这些实验结果,说明屎肠球菌SQ-1对小鼠的免疫功能具有增强作用。(4)对屎肠球菌SQ-1开展了安全性研究,实验包括:对20种抗生素敏感性检测、毒力基因PCR检测和小鼠口服屎肠球菌SQ-1后的脏器指数、血常规检测以及组织切片观察等。抗生素敏感性实验结果表明,屎肠球菌SQ-1对8种抗生素敏感,其中最具有代表性的万古霉素抑菌圈直径为19mm;对常见的六种毒力基因(Asa1、cyl A、efaA、esp、gel E、hyl)的PCR检测结果表明,屎肠球菌SQ-1不存在这六种毒力基因。在口服屎肠球菌SQ-1的安全性研究中,实验组和对照组相比较,脏器指数和血常规检测均无显著性差异;组织切片观察显示无病理变化,上述的安全性实验结果表明,屎肠球菌SQ-1的安全性较高。综上所述,屎肠球菌SQ-1具有较好的抗逆性和益生特性,同时安全性较好,这些为该菌株的生产开发提供了理论依据,也说明了该菌株有较好的应用前景。
[Abstract]:Probiotics, as a kind of feed additive, are more and more widely used in animal husbandry, and their feeding effect has been widely recognized by animal husbandry practitioners and scholars. But the probiotic characteristics of probiotics show obvious differences, so to obtain probiotic strains with good probiotics, we must carry out a lot of screening work. A probiotic strain with high bile salt tolerance was isolated and preserved in laboratory. The species, probiotics and safety of the probiotic strain were systematically studied in this paper. The specific contents and results are as follows: (1) by morphological observation, biochemical identification and 16s rDNA sequence alignment analysis, the strain was identified as Enterococcus faecium), and named as Enterococcus faecium SQ-1. (2) the probiotics of this strain were studied in vitro. The results show that: SQ-1 has good acid resistance, bile salt resistance, high temperature resistance and digestive enzyme resistance. The survival rate was 61.93% at pH 2.0 for 3 h, 90.37% for bile salt concentration for 3 h, 49.7% for bile salt concentration, 77.66% for 15min treated at 60 鈩，

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