Farrag Seham A, Marth Elmer H
Department of Food Science and The Food Research Institute, University of Wisconsin-Madison, Madison, Wisconsin 53706.
J Food Prot. 1989 Dec;52(12):852-855. doi: 10.4315/0362-028X-52.12.852.
Autoclaved samples of skim milk were inoculated with Listeria monocytogenes (strain Scott A, California or V7), Pseudomonas fluorescens (strain P26 or B52), or a combination of L. monocytogenes plus P. fluorescens , and incubated at 7 or 13°C for 8 weeks. McBride Listeria Agar was used to determine populations of L. monocytogenes (at 0, 7, 14, 28, 42, or 56 d), and Pseudomonas isolation agar to enumerate P. fluorescens . Growth of L. monocytogenes was somewhat enhanced after 7 d of incubation at 7 but not at 13°C in the presence of pseudomonads. However, after 14 d and until the end of the incubation period (56 d), slight inactivation of L. monocytogenes in the presence of P. fluorescens was observed. L. monocytogenes did not affect growth or survival of P. fluorescens ; also, no marked changes in pH of the milk were caused either by L. monocytogenes alone or by L. monocytogenes plus P. fluorescens .
将脱脂牛奶的高压灭菌样品接种单核细胞增生李斯特菌（菌株Scott A、加利福尼亚株或V7）、荧光假单胞菌（菌株P26或B52），或单核细胞增生李斯特菌与荧光假单胞菌的组合，并在7℃或13℃下孵育8周。使用麦克布赖德李斯特菌琼脂来测定单核细胞增生李斯特菌的数量（在0、7、14、28、42或56天），并使用假单胞菌分离琼脂来计数荧光假单胞菌。在7℃下孵育7天后，单核细胞增生李斯特菌的生长有所增强，但在13℃下，在有假单胞菌存在时则没有增强。然而，在14天后直至孵育期结束（56天），观察到在有荧光假单胞菌存在时，单核细胞增生李斯特菌有轻微失活。单核细胞增生李斯特菌不影响荧光假单胞菌的生长或存活；而且，无论是单核细胞增生李斯特菌单独存在还是与荧光假单胞菌共同存在，牛奶的pH值均未发生明显变化。
