内蒙古牧区传统乳制品中耐酸及耐胆盐植物乳杆菌的筛选

试验对从内蒙古通辽市科左后旗和扎鲁特旗牧民家的乳样中分离的27株植物乳杆菌的耐酸及耐胆盐特性进行研究。结果显示，有20株菌能耐受0．3％的牛胆酸钠，且对pH3．0的生长环境表现出不同程度的耐受性。其中8株菌耐受性较强，存活率最高可达150．6％，其余菌株从15．5％-39．8％不等。     

脱脂乳发酵体系中乳酸菌的高效离子交换色谱分析

应用高效离子交换色谱对脱脂乳发酵体系中的嗜热链球菌和保加利亚乳杆菌进行色谱表征。结果表明，单菌培养过程中保加利亚乳杆菌菌体形态的变化在其相应色谱行为上得到了体现，二者的色谱峰有比较好的稳定性。两种菌的峰面积与菌数之间呈现出良好的线性关系，可决系数R^2分别为0．9957和0．9916。因此本方法的建立，可用于酸奶发酵过程中乳酸菌的分析与表征，有望为乳酸菌混合物的研究提供一种快捷的新方法。     

Screening of Probiotics Inhibiting E. coli K88 in vitro

The probiotics tested in the experiment were isolated from the intestinal of weaning piglets.The isolated probiotics and E.coli K88 were inoculated into the culture of intestinal porcine epithelial cell-1 (IPEC-1).The activity of lactate dehydrogenase (LDH) in the supernatant was measured after incubating for 2.5 h.At the same time, the probiotics and E.coli K88 were co-cultured in vitro, the number of E.coli K88 was counted and the probiotics which could be resistant to the E.coli K88 were selected 2.5 h later.The results showed that the Lactobacillus casei and Bacillus coagulans could significantly reduce LDH activity (P<0.05), decrease the damage of E.coli K88; Bacillus coagulans could inhibit the growth of E.coli K88.At the same time, Bacillus coagulans could resist high temperature, acid and bile salt.The results showed that Bacillus coagulans strains had great potential as the application of probiotics strains.The methods could be used as a model of screen probiotics which could inhibit the growth of E.coli K88 in vitro.     

嗜酸乳杆菌生产共轭亚油酸的发酵条件研究

[目的]为提高微生物法发酵合成共轭亚油酸(CLA)的产量,优化嗜酸乳杆菌生产共轭亚油酸的发酵条件.[方法]试验以亚油酸为底物,利用嗜酸乳杆菌合成共轭亚油酸,选取对CLA的生成量影响显著的几个因素:底物浓度、接种量、pH、发酵时间、发酵温度进行单因素试验,并在此基础上进行正交试验优化发酵条件.[结果]单因素试验得到的最优发酵条件为底物浓度1.0 mg/ml、接种量4％、初始pH 5.5、发酵时间48 h、发酵温度37℃.正交试验发现,底物浓度、发酵时间、发酵温度显著影响CLA的合成产量.最终得到的最优发酵条件为底物浓度为1.5 mg/ml、接种量2％、初始pH 5.5、发酵时间36 h、发酵温度33℃.用气质联用法对产物进行定性分析,证明产物是c-9,t-11 CLA.此时,CLA的产量为91.54 μg/ml.[结论]试验优化了共轭亚油酸的发酵条件,为更有效率地利用嗜酸乳杆菌生产共轭亚油酸提供了理论依据.     

复合乳酸菌制剂的耐受性和抑菌性研究

本试验将四株饲用乳酸菌,制成复合乳酸菌制剂,通过单因素试验设计,以存活率为指标,研究复合微生态产品对高温、酸、胆盐的耐受性,采用琼脂稀释法、牛津杯法分别测定复合乳酸菌制剂对不同种类饲用抗生素的耐受性及对致病菌的抑制作用。结果表明:复合乳酸菌产品在温度65℃处理2.5、5、7.5 min以及85℃处理2.5 min对其存活率没有影响,但当85℃处理5 min,存活率下降至48%;p H为3时处理90 min存活率高达80.54%。对0.3%猪胆盐的耐受性较好,处理1 h存活率为73.52%;对抗生素(药物饲料添加剂)杆菌肽锌、亚甲基水杨酸杆菌肽耐受性最强,对吉他霉素的耐受性最差;可抑制致病菌株大肠埃希氏菌的生长。体外评价试验结果表明,复合乳酸菌制剂具有很好的益生特性,可进一步研究其在动物上的应用效果。     

德氏乳杆菌保加利亚亚种优良菌株的筛选

以分离自传统发酵乳的55株德氏乳杆菌保加利亚亚种为研究对象,通过分析其发酵时间、后酸化、黏度、脱水收缩性和游离氨基酸态氮等发酵特性,最终得到3株可作为酸乳发酵剂用的德氏乳杆菌保加利亚亚种菌株,分别为IMAU80319、IMAU20422和IMAU20404.     

Effects of Lactobacillus amylovorus Metabolites on the Barrier Function of IPEC-J2 Cells Infected by TGEV

This study used Real-time PCR to detect the changes of expression quantity of claudin 3 (CLDN-3), cytokeratin 8 (KRT8) and mucin 1 (MUC1) three proteins mRNA in IPEC-J2 cells at three different time points.IPEC-J2 cells were infected by TGEV, we explored whether Lactobacillus amylovorus metabolites could enhance cell barrier function by maintaining or improving mRNA expression of CLDN-3, KRT8 and MUC1, whether had effects on the barrier function of IPEC-J2 infected by TGEV.The results showed that mRNA expressions of MUC1, CLDN-3 and KRT8 in the normal cell control group did not change significantly with time (P> 0.05); MRS medium culture group did not change significantly compared to the normal cell control group(P> 0.05); Gene expressions of MUC1, CLDN-3 and KRT8 proteins in Lactobacillus amylovorus metabolites alone treatment group showed significant time-dependent effect (P< 0.05).After being treated 24, 36 and 48 h, gene expressions of MUC1, CLDN-3 and KRT8 proteins in Lactobacillus amylovorus metabolites+TGEV experiment group was significantly higher than virus control group (P< 0.05).Lactobacillus amylovorus metabolites could improve MUC1, CLDN-3 and KRT8 expressions in IPEC-J2 cells, while being able to negatively regulate MUC1, CLDN-3 and KRT8 expressions that TGEV induced in IPEC-J2 cells, thereby inhencing the barrier function of IPEC-J2 cell against TGEV.     

群体感应信号肽介导的产细菌素乳杆菌在发酵肠中的应用

为了解受群体感应信号肽介导的产细菌素乳杆菌作为发酵剂的潜力,以前期研究获得的1株Lactobacillus paraplantarum L-ZS9菌株为研究对象,L.plantarum L-Y9为对照,将L.paraplantarum L-ZS9+AIP(信号肽)、L.paraplantarum L-ZS9和L.plantarum L-Y9分别复配商用木糖葡萄球菌制备发酵香肠,测定不同发酵剂条件下各组香肠的微生物指标、理化指标和感官指标。结果表明:L-ZS9+AIP组效果最佳,与L-Y9组有显著差异(P0.05),但与L-ZS9组差异并不明显(P0.05)。L-ZS9作为发酵剂能够更迅速启动发酵,较好地抑制肠杆菌的生长,及丙二醛(MDA)的增加,同时提高发酵香肠的感官品质。     

不同组合益生菌对育成期水貂生长性能和消化代谢规律的影响

本试验旨在研究不同组合益生菌对育成期水貂生长性能和营养物质消化率及氮平衡的影响。选择96只60日龄、健康状况良好的水貂,随机分为4组,每组24只,公、母各半。对照组饲喂基础日粮,试验1、2、3组分别在基础日粮中添加0.06 g地衣芽孢杆菌+0.06 g枯草芽孢杆菌、6 g安琪酵母+12 mL乳酸菌、0.06 g地衣芽孢杆菌+0.06 g枯草芽孢杆菌+6 g安琪酵母+12 mL乳酸菌。在水貂育成期内进行饲养与消化代谢试验,分析不同组合益生菌对水貂平均日采食量、平均日增重、料重比、粗蛋白质和粗脂肪的消化率及沉积氮、蛋白质生物学价值和净蛋白质利用率的影响。结果表明,与对照组相比,试验1组公貂的干物质消化率和试验2组公貂的脂肪消化率显著下降(P<0.05),但不同组水貂的生长性能和氮平衡及母貂的营养物质消化率未受到益生菌的影响(P>0.05)。提示,日粮中添加益生菌不会显著改善育成期水貂的生长性能、营养物质消化率及氮平衡,故在水貂健康的前提下,无需在育成貂日粮中添加益生菌。     

补喂复合益生菌对3～6月龄伊犁马粪便纤维含量、挥发性脂肪酸浓度和血浆细胞因子水平的影响

试验旨在研究补喂复合益生菌对3～6月龄伊犁马粪便纤维含量、VFA浓度和血浆细胞因子水平的影响。选取体重相近(90.23kg±11.02kg)、健康状况良好的3月龄伊犁马哺乳马驹10匹,随机分为2组,每组5匹,分别为对照组和试验组。在分阶段补喂等量营养水平的精料补充料和苜蓿干草的基础上,试验组每匹马驹每天补喂0.075g(2×10¹¹ CFU/g)枯草芽孢杆菌和0.133g(3×10¹⁰ CFU/g)植物乳杆菌复合菌,进行为期90d的饲养试验。结果显示,补喂复合益生菌能够显著或极显著降低马驹粪便中酸性洗涤纤维(ADF)和淀粉的含量(P<0.05;P<0.01),分别比对照组低3.50%和11.32%;显著或极显著提高马驹粪便中乙酸和丙酸的浓度(P<0.05;P<0.01),分别比对照组高14.65%和64.29%;极显著提高血浆中肿瘤坏死因子α(TNF-α)的水平(P<0.01),比对照组高16.17%。由此可见,补喂复合益生菌能够降低马驹粪便中纤维的含量、提高挥发性脂肪酸(VFA)的浓度,增加3～6月龄伊犁马血浆细胞因子水平。