关键词：
E. faecium;sausage;bactericoin HY07;production
摘要：
In this study, we present a partial purification of bacteriocin HY07 from E. faecium HY07 isolated from Chinese sausage, which exhibited antimicrobial activity to Listeria, Salmonella, Shigella, Staphylococcus, Clostridium, and Bacillus. E. faecium HY07 was shown to lack haemolytic activity and found to be sensitive to tested antibiotics (rifampicin, vancomycin, teicoplanin, and penicillin G). Bacteriocin HY07 was sensitive to proteolytic enzymes, but stable between pH 2.0–10, and heat resistance (15 min at 121°C). In addition, production of bacteriocin HY07 started at the early exponential phase and reached its maximum at the stationary phase, and exerted bacteriostatic effect to Listeria monocytogenes 54002. Bacteriocin HY07 was estimated below 6.5 kDa by tricine-SDS-PAGE. Growth in the presence of tryptone stimulated bacteriocin production. However, lower activity was recorded when the bacteria were grown in the presence of meat extract or yeast extract. MRS broth supplemented with 20 g/L glucose yielded bacteriocin levels of 160 AU/mL, but the production of bacteriocin HY07 was repressed by more than 50% when glucose exceeded 30 g/L. Growth in the presence of maltose, fructose, fructose, sucrose, lactose, and galactose yielded lower activity of bacteriocin. MRS medium supplemented with glycerol repressed bacteriocin production.
作者机构：
[周红丽; 谭兴和; 李清明] Hunan Province Key Laboratory of Food Science and Biotechnology, Changsha, China;[刘志伟; 周红丽; 谭兴和; 李清明] College of Food Science and Technology, Hunan Agricultural University, Changsha, China
通讯机构：
Hunan Province Key Laboratory of Food Science and Biotechnology, Changsha, China
关键词：
优化;酶;水解;响应面分析法;南瓜籽粕;血管紧张素转化酶抑制肽;水解度
摘要：
用中性蛋白酶水解南瓜籽粕,制备血管紧张素转换酶(angiotensin—converting enzyme,ACE)抑制肽,是南瓜籽粕蛋白深度开发的途径之一。为了探寻南瓜籽粕酶法制备ACE抑制肽的最佳工艺,该文以ACE抑制率为响应值,用响应面分析法研究酶浓度、底物质量浓度和水解时间等因素对酶解产物的ACE抑制活性的影响,优化制备工艺。结果表明,各因素对制备ACE抑制肽的活性具有极显著影响(P<0.001)。获得中性蛋白酶水解南瓜籽粕制备ACE抑制肽的最佳工艺条件为:酶体积分数为4.8%、底物质量浓度为4.0g/100 m L、水解时间为320 min。在此条件下,南瓜籽粕蛋白酶解产物对ACE的理论抑制率最高可达80.0%,验证值为80.56%±0.23%,预测模型可靠性高,可应用于南瓜籽粕ACE抑制肽的酶法制备。通过优化,提高了南瓜籽粕ACE抑制肽的活性。
摘要：
为得到一种外观诱人、口味独特的具有市场开发价值的营养保健型酸奶,以胡萝卜汁、苹果汁、鲜牛奶为原料,以保加利亚乳杆菌和嗜热链球菌为发酵剂进行乳酸发酵,通过L_9(3~4)正交试验,得出研制凝固型胡萝卜汁、苹果汁复配酸奶的最佳工艺参数:胡萝卜汁、苹果汁、白砂糖、发酵剂的质量分数分别为25%,8%,9%,6%;发酵温度(42±1)℃;发酵时间4 h.
