【作者】 崔建超；

【导师】 张柏林； 贾英民；

【作者基本信息】 河北农业大学 ， 农产品贮运与加工工程， 2002， 硕士

【摘要】 采用琼脂扩散交叉拮抗的方法，从25株乳酸菌中筛选得到了4株细菌素产生菌株，它们是1株嗜酸乳杆菌(Lactobacillus acidphilus Ind-1)，1株戊糖片球菌(Pediococcus pentosaceus)及2株植物乳杆菌(Lactobacillus plantarum A，Lactobacillus plantarum B)。 对菌株生长特性、营养代谢以及发酵参数的研究表明，植物乳杆菌A的最佳碳源和氮源为蔗糖和鱼蛋白胨；植物乳杆菌B的最佳碳源和氮源为葡萄糖和鱼蛋白胨；嗜酸乳杆菌Ind-1的最佳碳源和氮源分别为乳糖和大豆蛋白胨；戊糖片球菌的最佳碳源和氮源分别为乳糖和鱼蛋白胨。 研究表明，当培养基初始pH为6.5时菌株代谢产生活性最高的细菌素。对四种细菌素的生化特性研究表明，它们都有良好的热稳定性(100℃加热20min不失活)。这四种细菌素对胃蛋白酶、蛋白酶K和胰蛋白酶都较敏感。戊糖片球菌产生的细菌素对木瓜蛋白酶敏感，而其它三种细菌素对这种蛋白酶稳定。pH稳定性研究表明，在弱酸性或中性条件下，这些细菌素表现出较高的活性。四株产细菌素菌株对大部分乳酸菌都有不同程度的抑制作用。嗜酸乳杆菌Ind-1以及戊糖片球菌产生的细菌素对食品腐败菌和致病菌(如大肠杆菌和金黄色葡萄球菌)有较好的抑制效果，且抑菌谱较宽。植物乳杆菌A和植物乳杆菌B对大部分乳酸菌都有抑制作用，但是对金黄色葡萄球菌、大肠杆菌和巨大芽孢杆菌抑制作用较差。 在4℃或22℃保存条件下，向消毒奶中投放由嗜酸乳杆菌Ind-1和戊糖片球菌形成的细菌素后，消毒奶的保存期限至少延长了4天或2天。在4℃保存条件下，投放嗜酸乳杆菌Ind-1和戊糖片球菌产细菌素菌体细胞到消毒奶中，能够有效抑制杂菌生长，使其货架期延长3天左右。在4℃下，应用嗜酸乳杆菌Ind-1和戊糖片球菌产细菌素菌体细胞作为生物型保护剂，能够明显改善鲜乳的货架期，使其保存期限提高2天左右。然而，当原料奶与消毒奶保存在22℃时，试验期内向其投放嗜酸乳杆菌Ind-1和戊糖片球菌产细菌素菌体细胞并不能有效提高它们的货架期。更多还原

【Abstract】 Four bacteriocin-producing strains were screened from 25 strains of lactic acid bacteria obtained from different sources. They were Lactobacillus acidophilus Ind-I, Pediococcus pentosaceus, Lactobacillus plantanan A and Lactobacillus plantarum B. The effects of carbohydrate and nitrogen on the production of bacteriocin were investigated. The optimum sugar and nitrogen used to produce the largest activity of bacteriocins were sucrose and peptone for L. plantarum A, glucose and peptone for L. plantarum A, lactose and soy peptone forZ,. acidophilus Ind-1, and lactose and peptone for P. pentosaceus, respectively. The initial pH with 6.5 in media allowed the four studied strains to form the highest bacteriocins activity against sensitive organisms. The biological properties of four kinds of bacteriocins showed they were heat stable and did not lost activity when heated at 100癈 for 20 minutes. All the bacteriocins were sensitive to pepsin, proteinase K and trpsin. The three bacteriocins produced by strains L. acidphilus Ind-1, L. plantarum A and B were resistant to the enzyme trpsin, except for the bacteriocin produced by P. pentosaceus. These four bacteriocins showed the highest antibacterial activity under acidulous and neutral conditions. The bacteriocin-producing strains inhibited most of related lactic acid bacteria. The bacteriocins produced by strains L. acidophilus Ind-1 and P. pentosaceu were effective against food spoilage and pathogenic bacteria like Escherichia coli and Staphylococcus aureus. The strains of I. plantarum A and B were effective against many of lactic acid bacteria, but ineffective towards S.aureus, E.coli and Bacillus megaterium. The crude bacteriocins as well as the cells of bacteriocins-producing strains were added to the pasteurized and raw milks to study their effects on the shelf life of dairy products. Addition of bacteriocins produced by L. acidophilus Ind-1 and P. pentosaceu to pasteurized milk led to an extended shelf life of 4 days at 4癈 or 2 days at 22癈. When the cells of the two bacteriocin-producing strains were added to pasteurized milk which was stored at 4癈, it might extended the shelf life of pasteurized milk for at least 3 days. The shelf life of raw milk stored at 4癈 could be extended for 2 days if the bacteriocin-producing cells of L. acidophilus md-1 and P. pentosaceu were added to raw milk. However, addition of the cells of the two bacteriocin-producing strains to pasteurized and/or raw milks were not effective on improving their shelf life when the two kinds of milk were stored at 22癈.更多还原