Ferreira M A, Lund B M
Institute of Food Research, Colney, Norwich, UK.
Lett Appl Microbiol. 1996 Jun;22(6):433-8. doi: 10.1111/j.1472-765x.1996.tb01197.x.
The sensitivity to nisin of 27 strains of Listeria monocytogenes, four of L. innocua and one of L. ivanovii was estimated at pH 6.8 and pH 5.5. Strains of L. monocytogenes showed differences in sensitivity which were not correlated with serotype. Strains of L. innocua were as resistant as the most resistant strains of L. monocytogenes, whereas the strain of L. ivanovii was relatively sensitive. Two of the most resistant strains of L. monocytogenes multiplied in aerated liquid medium adjusted to pH 5.0 with HCl, incubated at 20 degrees C; nisin, 500 IU ml-1, prevented multiplication and caused death. Following inoculation of a resistant strain into long-life cottage cheese, pH 4.6-4.7, the number of viable L. monocytogenes decreased approximately 10-fold during storage at 20 degrees C for 7 d; addition of nisin, 2000 IU g-1, to the cottage cheese increased the rate of inactivation to approximately a 1000-fold decrease in 3 d.
在pH 6.8和pH 5.5条件下，对27株单核细胞增生李斯特菌、4株无害李斯特菌和1株伊氏李斯特菌进行了乳酸链球菌素敏感性评估。单核细胞增生李斯特菌菌株在敏感性上存在差异，且与血清型无关。无害李斯特菌菌株与单核细胞增生李斯特菌中抗性最强的菌株一样具有抗性，而伊氏李斯特菌菌株相对敏感。两株抗性最强的单核细胞增生李斯特菌菌株在经盐酸调节至pH 5.0的通气液体培养基中于20℃培养时能够生长；500 IU/ml的乳酸链球菌素可抑制其生长并导致其死亡。将一株抗性菌株接种到pH 4.6 - 4.7的长效农家干酪中后，在20℃储存7天期间，单核细胞增生李斯特菌的活菌数大约减少了10倍；向农家干酪中添加2000 IU/g的乳酸链球菌素可使灭活速率提高，在3天内活菌数大约减少1000倍。
