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目的从肉仔鸡肠道中筛选出耐酸、耐胆盐和耐消化酶的优良双歧杆菌,研究其生长特性,并优化其发酵参数,为转化生产力提供理论依据。方法通过无菌采样并分离得到多株双歧杆菌,对分离获得的双歧杆菌进行形态学、生化特性研究,然后采用牛津杯法,测定90株双歧杆菌对大肠埃希菌和沙门菌的抑制作用,采用改良MRS培养基,模拟鸡胃肠道逆环境,对其耐消化道特性进行研究,筛选出优良双歧杆菌,再进行生长特性研究及发酵参数优化。结果从肉仔鸡肠道分离出90株双歧杆菌,初步挑选出23株作为候选菌株,抑菌试验测得双歧杆菌B1、B2和B3具有良好的抑菌效果,然后经过耐受消化道逆环境试验,发现B2菌株的耐受能力最好,初步鉴定双歧杆菌B2为小鸡双歧杆菌,并将其定名为Bifidobacterium pullorum B2,对其生长特性的研究发现经18 h发酵细菌总数可以从8.3×105CFU/mL升高到1.3×109CFU/mL,运用优化的发酵培养基进行中试试验,发酵后的活菌数可达1.41×1010CFU/mL。结论本实验从肉仔鸡肠道中分离筛选并初步鉴定了Bifidobacterium pullorum B2,优化了制备Bifidobacterium pullorum B2发酵液的发酵条件,降低了生产成本。
OBJECTIVE To screen excellent Bifidobacterium that tolerate acid, bile salt and digestive enzymes from broiler intestine, study its growth characteristics and optimize its fermentation parameters to provide a theoretical basis for transforming productivity. Methods Bifidobacterium was isolated by aseptic sampling and the bifidobacteria were isolated. The morphological and biochemical characteristics of bifidobacteria were studied. After that, the bifidobacteria of 90 strains were tested against Escherichia coli and Salmonella The modified MRS medium was used to simulate the reverse environment of gastrointestinal tract in chicken. The characteristics of gastrointestinal tract were studied, and the excellent Bifidobacterium was screened. The growth characteristics and fermentation parameters were optimized. Results Ninety Bifidobacterium strains were isolated from the intestine of broiler chickens and 23 strains were initially selected as candidate strains. The bacteriostasis tests showed that Bifidobacteria B1, B2 and B3 had good antibacterial activity, Environmental tests showed that strain B2 was the best tolerant. Bifidobacterium B2 was identified as Bifidobacterium cholerae and was named as Bifidobacterium pullorum B2. The growth characteristics of strain B2 were studied. The total number of bacteria after 18 h fermentation was 8.3 × 105CFU / mL to 1.3 × 109CFU / mL, and the optimized fermentation medium was used for pilot test. The viable count after fermentation was 1.41 × 1010CFU / mL. Conclusion In this experiment, Bifidobacterium pullorum B2 was isolated and identified from the intestine of broiler chickens. The fermentation conditions for the preparation of Bifidobacterium pullorum B2 fermentation broth were optimized and the production cost was reduced.