文档介绍：中文摘要
细菌素是食品级微生物的代谢产物,有的细菌素已作为食品防腐剂用于提高食品的安全性。本研究的目的是以从国内发酵食品中分离出的乳酸片球菌(us acidtTactici)为研究对象,探索提高其片球菌素产率的培养条件, 研究片球菌素的分离纯化技术和活性测定方法,并阐明其抗菌物质的本质和理化特性。
本研究对乳酸片球菌所产的抑菌物质进行H202酶处理、酸性产物抑菌作用排除试验和胃蛋白酶、胰蛋白酶、木瓜蛋白酶、蛋白酶K的处理试验,证明该菌所产的抗菌物质,不是H202和酸性产物,并且对蛋白酶敏感,因而确认该菌产生的抑菌物质为蛋白质性质的细菌素。将乳酸片球菌接种于MRS培养基,对产生细菌素的条件进行优化,确定其有最大细菌素产量时培养基的初始pH为
,静置培养温度为37℃,培养时间为16h。
本研究对几种分离体系进行了摸索比较,最终建立了三步法体系对片球菌素 Pediocin进行分离纯化。,,通过调节pH和离心来收集细菌素。透析并冷冻干燥浓缩后经过SP
Sepharose Fast Flow阳离子交换柱层析和Sephadex ,收集有活性的峰。经过分离纯化三步法后,与培养上清液相比,细菌素的最终得率
%,×104AU/mg,。提纯的细菌素样品经过聚丙烯酰***凝胶电泳分析,出现了单一的条带,这就证明己得到了较纯的细菌素, 其大小约为4600Da。
本研究还对片球菌素Pediocin的理化性质作了全面的观察。试验表明,细菌
素在20℃一100℃的条件下保温20rain活性没有太大变化,具有很高的热稳定性;
在pHllHl4的条件下20"C处理3h抑菌效果稳定,具有良好的耐酸碱特性;经有
机溶剂处理过的细菌素样仍能保持较好的抑菌活性,有机溶剂对细菌素活性的影响不显著;冷冻、冷藏后细菌素仍能具有很好的抑菌活性,且冷冻后的活性还要优于冷藏后的效果。
乳酸片球菌细菌素具有被开发为安全和高效生物食品防腐剂的巨大潜力,本研究建立的乳酸片球菌细菌素的分离纯化技术及关于其理化性质探索的研究将为乳酸片球菌细菌素的工业化生产和实际应用提供理论依据。
关键词:细菌素分离纯化性质
AB STRACT
Bacteriocins were metabolited products of food-grade anisms,and some of which were used as f00d preservative to impove the food bacteriocin producing strain us acidilactici was isolated from fermented vegetable food
in the previous eultive conditions were optimized,the purification
technologies and the activity determination method were studied,and the characteristics of the bacteriocin were also explained.
The antibacterial substance secreted by us acidilactici was treated with
acidities and some proteinases including hydrogen pemxidase,pepsin,trypsin,papain and proteinase results suggested that the antibacteriocin substance Was not H202 and acid metabolization,and it WaS sensitive to some the study showed it Was bacteriocin,and it was called in MRS culture medium,the cultive conditions of maximum production of bacteriocin were beginning pH was ,the cultivate temperature was 37"C and the
cultivate time was 1 6 hours.
The b