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 Aug;52(8):536-539. doi: 10.4315/0362-028X-52.8.536.
Tryptose broth (TB) was inoculated with Listeria monocytogenes (strain Scott A or California), Pseudomonas aeruginosa , Pseudomonas flourescens , or a combination of L. monocytogenes plus Pseudomonas species, and incubated at 7 or 13°C for 8 weeks. McBride Listeria Agar was used to determine numbers of L. monocytogenes and Pseudomonas Isolation Agar to enumerate Pseudomonas species at 0, 7, 14, 28, 42, or 56 d. At 13°C, presence of P. fluorescens had a slight negative effect on growth of L. monocytogenes strain Scott A, and was somewhat detrimental to its survival during the extended incubation. Growth of L. monocytogenes strain California was retarded by presence of P. fluorescens although the maximum population achieved by the pathogen was greater in the presence rather than absence of the pseudomonad; the pseudomonad did have a negative effect on survival of the pathogen. At the same temperature, P. aeruginosa had a negative effect on survival of L. monocytogenes strain California, but had essentially no effect on the other strain of the pathogen. Neither strain of L. monocytogenes affected growth of P. fluorescens nor P. aeruginosa . At 13°C the pH of TB generally decreased when L. monocytogenes grew by itself but increased when either pseudomonad grew by itself or together with the pathogen. At 7°C, growth of both pseudomonads was minimal. Presence of non-growing cells of P. fluorescens retarded somewhat growth of both L. monocytogenes strains early during the incubation. P. aeruginosa had no detectable effect on either strain of L. monocytogenes . The pH of TB decreased when L. monocytogenes grew by itself or together with either pseudomonad, and remained unchanged in TB inoculated with either pseudomonad.
将产单核细胞李斯特菌（斯科特A菌株或加利福尼亚菌株）、铜绿假单胞菌、荧光假单胞菌或产单核细胞李斯特菌与假单胞菌属的组合接种到胰蛋白胨肉汤（TB）中，并在7℃或13℃下培养8周。使用麦克布赖德李斯特菌琼脂测定产单核细胞李斯特菌的数量，并用假单胞菌分离琼脂在第0、7、14、28、42或56天对假单胞菌属进行计数。在13℃时，荧光假单胞菌的存在对产单核细胞李斯特菌斯科特A菌株的生长有轻微的负面影响，并且在延长培养期间对其存活有些不利。荧光假单胞菌的存在会抑制产单核细胞李斯特菌加利福尼亚菌株的生长，尽管在有假单胞菌存在时病原体达到的最大菌量比没有假单胞菌时更大；假单胞菌确实对病原体的存活有负面影响。在相同温度下，铜绿假单胞菌对产单核细胞李斯特菌加利福尼亚菌株的存活有负面影响，但对病原体的另一菌株基本没有影响。产单核细胞李斯特菌的两个菌株均不影响荧光假单胞菌或铜绿假单胞菌的生长。在13℃时，当产单核细胞李斯特菌单独生长时，TB的pH值通常会下降，但当任何一种假单胞菌单独生长或与病原体一起生长时，pH值会升高。在7℃时，两种假单胞菌的生长都很微弱。荧光假单胞菌的非生长细胞的存在在培养早期对产单核细胞李斯特菌的两个菌株的生长都有一定程度的抑制。铜绿假单胞菌对产单核细胞李斯特菌的两个菌株均未检测到有影响。当产单核细胞李斯特菌单独生长或与任何一种假单胞菌一起生长时，TB的pH值会下降，而接种任何一种假单胞菌的TB的pH值保持不变。
