【作者】 苏勇；

【导师】 朱伟云；

【作者基本信息】 南京农业大学 ， 动物营养与饲料科学， 2004， 硕士

【摘要】 为了充分发挥芽孢乳杆菌S1的益生作用，并且了解其在仔猪胃肠道中的作用机理，本研究从S1的生长特性、药敏性，外源物质的促生长作用及大豆黄酮和脱脂乳对S1耐受酸和胆盐的保护等方面对S1的益生作用做了优化，此外，通过动物试验对S1的作用机理作了初步探讨。试验分成四部分： 一 芽孢乳杆菌S1生长特性及对常用药物的敏感性研究 为了研究芽孢乳杆菌S1的生长特性，于体外发酵的不同时间点，测定了S1发酵液的OD₆₀₀值和pH值。结果表明：S1具有较快的生长速度，2h进入对数生长期，10 h进入稳定期，稳定期后菌液pH值降低至4.5以下，菌液的OD值与pH值呈现一定的相关性。同时研究了芽孢乳杆菌S1、德氏乳杆菌L7和大肠杆菌O141对常用药物的敏感性，结果表明，大多数药物对S1的最低抑菌浓度（MIC）较其对L7和O141高。 二 不同底物和大豆黄酮对乳酸菌生长的影响 基础培养基中分别添加0.5％葡萄糖、0.3％酵母膏、0.5％甜菜渣、0.5％玉米芯和0.5％桔皮粉，研究不同底物对乳酸菌生长的影响，基础培养基组作为对照组；同时在MRS液体培养基中分别添加10、20、50、100 mg·L^-1大豆黄酮，研究大豆黄酮对乳酸菌生长的影响。结果表明：与对照组相比，添加0.3％酵母膏和0.5％桔皮粉明显提高了乳酸菌的生长速度及乳酸产量；添加0.5％甜菜渣、0.5％玉米芯后，乳酸菌的生长速度略快于对照组，但乳酸产量相近；添加0.5％葡萄糖没有提高乳酸菌的生长速度，但10 h后，乳酸产量较对照组高；大豆黄酮对乳酸菌的生长没有明显影响。 三 大豆黄酮和脱脂乳对芽孢乳杆菌S1耐受胆盐和酸的影响 通过体外实验研究了大豆黄酮和脱脂乳对芽孢乳杆菌S1在不同pH值和不同浓度胆盐下存活能力的影响。结果表明，与对照组比，添加1％的脱脂乳显著提高了S1在pH分别为2.6、3.7条件下的存活数量，并且也能显著提高S1在0.1％、0.2％、0.3％胆盐浓度条件下的存活数量，说明1％的脱脂乳对S1有显著的保护作用。添加50 mg·L^-1的大豆黄酮也明显提高S1耐胆盐的能力，但对S1耐受酸能力呈负效果。 四 芽孢乳杆菌S1对断奶前、后仔猪肠道菌群及VFA浓度变化的影响 试验比较了芽孢乳杆菌S1冷冻液与冻干粉在制备和保存过程中的存活效果，为饲养试验选择一种理想的乳酸菌制剂形式，结果表明S1冷冻液存活效果较佳。6窝仔猪随机分成两组，即对照组和乳酸菌组，旨在研究外源乳酸菌对仔猪从7日龄至35日龄空肠和结肠食糜中乳酸菌和大肠杆菌的数量变化及挥发性脂肪酸（VFA）浓度变化的影响。结果表明：芽抱乳杆菌51的益生作用优化及其作用机理初探仔猪断奶前，空肠和结肠食糜中乳酸菌和大肠杆菌的数量变化较稳定;断奶后，仔猪空肠和结肠食糜中乳酸菌和大肠杆菌的数量均明显下降，乳酸菌的下降更显著;与对照组相比，外源乳酸菌能提高断奶后仔猪空肠和结肠食糜中乳酸菌与大肠杆菌的数量比值。断奶后，仔猪结肠vFA浓度明显下降，与对照组相比，外源乳酸菌能提高结肠VFA浓度。更多还原

【Abstract】 A lactic acid bacterial strain, Sporolactobacillus S1, was investigated to explore its probiotic activity. The growth property of the strain and its sensitivity to antibiotics were determined. A range of different substrates were screened for beneficially stimulating the growth of lactic acid bacteria (LAB). The effects of daidzein and skimmed milk on the survival of Sporolactobacillus S1 were investigated under different pH and bile salt conditions. To further understand the probiotic role of the strain in the intestine of piglets, an in vivo experiment was also conducted. This thesis includes four sections.In the first section, growth properties of Sporolactobacillus S1 were analyzed by monitoring the development of growth density and pH in the culture during incubation. The results showed that the growth of S1 was rapid. S1 reached its exponential growth phase after 2 h incubation and went into stationary growth phase after 10 h. In stationary phase, the pH value of the culture declined to below 4.5. Sporolactobacillus S1 was also compared with Lactobacillus L7 and E. coli O141 in their sensitivity to antibiotics. The results showed that the mimimal inhibitory concentration (MIC) of most antibiotics on S1 was higher than those on L7 and 0141.In the second section, a range of substrates (0.5% glucose, 0.3% yeast extract, 0.5% sugar-beet dregs, 0.5% corncob and 0.5% citrus peel powder) were screened for their effect on the growth of lactic acid bacteria (LAB). The effect of daidzein at 10, 20 , 50, 100 mg L-1 on the growth of LAB were also analyzed. The results showed that as compared with the control group, the addition with 0.3% yeast extract and 0.5% citrus peel powder improved the growth of LAB and apparently increased their lactic acid production. The growth of the LAB was slightly faster with the addition of 0.5% sugar beet dregs and 0.5% corncob than the control group, but the lactic acid productions were similar. The addition of 0.5% glucose did not enhance the growth of LAB, but increased the lactic acid production after 10 h incubation. However, daidzein showed no significant effect on the growth ofLAB in culture.In the third section, in vitro experiments were conducted to investigate the effects of daidzein and skimmed milk on the survival of Sporolactobacillus S1 under different pH and bile salt conditions. The results showed that under either low pH or bile salt conditions SI survival counts with the addition of 1% skimmed milk were significantly higher than those in the control. As compared with the control, treatment with 50 mg 鈥?L"1 daidzein enhanced the S1 survival counts under bile salt conditions, but decreased the survival counts under low pH conditions.In the fourth section, in order to obtain an ideal preparation of Sporolactobacillus SI for piglets experiment, two preparation forms ( freeze drying powder and freezing liquid ) were compared by enumeration of SI survival counts during processing and preservation. The results indicated that SI in the form of freezing liquid showed higher survival rate than in the form of freeze drying powder. To investigate the effects of Sporolactobacillus SI on E. coli and LAB counts in jejunum and colon of piglets and the fluctuation of VFA concentration in colon of piglets from 7 days of age to 35 days of age. six litters of piglets were divided randomly into two groups, namely the control group and LAB group. The results showed that the counts of E. coli and LAB in jejunum and ileum was stable before weaning. After weaning both the counts of E. coli and that of LAB in jejunum and colon showed apparent decrease, but the decrease of LAB count was more significantly than that of E. coli. As compared with the control group, oral administration with Sporolactobacillus SI enhanced the ratio of the LAB count to the E. coli count in jejunum and colon of piglets after weaning. The VFA concentration in colon of piglets decreased obviously after weaning. Treatment with S1 could apparently increase the VFA concentration in colon of piglets as compared w更多还原