Yildirim Z, Johnson M G
Department of Food Science and Arkansas Biotechnology Center, University of Arkansas, Fayetteville 72704, USA.
Lett Appl Microbiol. 1998 Apr;26(4):297-304. doi: 10.1046/j.1472-765x.1998.00335.x.
Bacteria isolated from radish were identified as Lactococcus lactis subsp. cremoris R and their bacteriocin was designated lactococcin R. Lactococcin R was sensitive to some proteolytic enzymes (proteinase-K, pronase-E, proteases, pepsin, alpha-chymotrypsin) but was resistant to trypsin, papain, catalase, lysozyme and lipase, organic solvents, or heating at 90 degrees C for 15, 30 and 60 min, or 121 degrees C for 15 min. Lactococcin R remained active after storage at -20 and -70 degrees C for 3 months and after exposure to a pH of 2-9. The molecular weight of lactococcin R was about 2.5 kDa. Lactococcin R was active against many food-borne pathogenic and food spoilage bacteria such as Clostridium, Staphylococcus, Listeria, Bacillus, Micrococcus, Enterococcus, Lactobacillus, Leuconostoc, Streptococcus and Pediococcus spp., but was not active against any Gram-negative bacteria. Lactococcin R was produced during log phase and reached a maximum activity (1600 AU ml-1) at early stationary phase. The highest lactococcin R production was obtained in MRS broth with 0.5% glucose, at 6.5-7.0 initial pH values, 30 degrees C temperature and 18-24-h incubation times. Lactococcin R adsorbed maximally to its heat-killed producing cells at pH 6-7 (95%). Crude lactococcin R at 1280 AU ml-1 was bactericidal, reducing colony counts of Listeria monocytogenes by 99.98% in 3 h. Lactococcin R should be useful as a biopreservative to prevent growth of food-borne pathogenic and food spoilage bacteria in ready-to-eat, dairy, meat, poultry and other food products. Lactococcin R differs from nisin in having a lower molecular weight, 2.5 kDa vs 3.4 kDa, and in being sensitive to pepsin and alpha-chymotrypsin to which nisin is resistant.
从萝卜中分离出的细菌被鉴定为乳酸乳球菌乳脂亚种R，其细菌素被命名为乳球菌素R。乳球菌素R对某些蛋白水解酶（蛋白酶K、链霉蛋白酶E、蛋白酶、胃蛋白酶、α-胰凝乳蛋白酶）敏感，但对胰蛋白酶、木瓜蛋白酶、过氧化氢酶、溶菌酶和脂肪酶、有机溶剂具有抗性，或在90℃加热15、30和60分钟，或在121℃加热15分钟后仍具有抗性。乳球菌素R在-20℃和-70℃储存3个月以及在pH值为2-9的环境中暴露后仍保持活性。乳球菌素R的分子量约为2.5 kDa。乳球菌素R对许多食源性病原体和食品腐败细菌具有活性，如梭菌属、葡萄球菌属、李斯特菌属、芽孢杆菌属、微球菌属、肠球菌属、乳杆菌属、明串珠菌属、链球菌属和片球菌属，但对任何革兰氏阴性细菌均无活性。乳球菌素R在对数期产生，并在稳定期早期达到最大活性（1600 AU ml-1）。在含有0.5%葡萄糖、初始pH值为6.5-7.0、温度为30℃且培养时间为18-24小时的MRS肉汤中，乳球菌素R的产量最高。乳球菌素R在pH值为6-7时最大程度地吸附到其热灭活的产生细胞上（95%）。浓度为1280 AU ml-1的粗制乳球菌素R具有杀菌作用，在3小时内可使单核细胞增生李斯特菌的菌落数减少99.98%。乳球菌素R作为一种生物防腐剂，可用于防止即食食品、乳制品、肉类、家禽和其他食品中食源性病原体和食品腐败细菌的生长。乳球菌素R与乳链菌肽的不同之处在于其分子量较低，分别为2.5 kDa和3.4 kDa，并且对乳链菌肽具有抗性的胃蛋白酶和α-胰凝乳蛋白酶敏感。
