Studies on the behavior of Listeria monocytogenes and its control in fishery products

研究了单核细胞增生李斯特菌在水产环境和水产品中的行为，以及生物保鲜技术在水产品中单核细胞增生李斯特菌防治中的应用。在水体环境中，在营养污染较严重的河流中检出单增李斯特菌。在海水中，单核增生l.g在较低温度下保持较长时间的可培养状态，也可能进入活但不可培养（VBNC）状态。在海水等营养条件较弱的条件下，单核增生l.g细胞比新鲜培养的细胞更能抵抗某些胁迫。在某些发酵水产品中接种单核细胞增生乳杆菌后，在贮藏过程中单核细胞增生乳杆菌数量减少，这主要受贮藏温度、原料和产品中乳酸菌含量的影响。通过筛选抑制单增李斯特菌生长的细菌，从冷冻鱼糜中分离出了部分乳酸菌菌株。piscicola Carnobacterium CS526产生了一种新的IIa类细菌素piscicocin CS526，其分子质量为4,430 Da，在n端具有独特的YGNGL氨基酸序列。Carnobacterium sp.Sur602根据培养基中酪蛋白的浓度产生细菌素样物质。piscicocin CS526干扰细胞质膜的杀菌功能，并伴有K +离子的外排、膜电位的耗散和胞内ATP的快速耗竭。piscicola CS526能有效抑制冷熏鲑鱼体内单核细胞增生杆菌的生长。细菌素及其产生物在水产品防单增李斯特菌生物保鲜方面具有潜在的应用价值。

Behavior of Listeria monocytogenes in aquatic environment and fishery products, and applicability of biopreservation to control of L.monocytogenes in the products were investigated. In aquatic environment, L.monocytogenes was detected in a river with higher nutritional pollution. In seawater L.monocytogenes maintained the culturable state longer at lower temperature and also might enter a viable but nonculturable (VBNC) state. In nutritionally weak condition like seawater, L.monocytogenes cells became more resistant against some stresses than freshly cultured cells.Inoculated in some fermented fishery products, L.monocytogenes decreased during storage, which was affected by storage temperature, ingredients and inclusion of lactic acid bacteria in the products. As a result of screening for bacteria inhibiting growth of L.monocytogenes, some strains of lactic acid bacteria were isolated from frozen surimi. Carnobacterium piscicola CS526 produced a novel class IIa bacteriocin, piscicocin CS526, which had a molecular mass of 4,430 Da and a unique amino acid sequence of YGNGL at the N-terminal. Carnobacterium sp.Sur602 produced bacteriocin-like substances depending on casein concentration in the medium. The piscicocin CS526 perturbed functions of the cytoplasmic membrane to act bactericidally against L.monocytogenes accompanied with the efflux of K^+ ions, dissipation of membrane potential, and rapid depletion of intracellular ATP. C.piscicola CS526 was effective to inhibit growth of L.monocytogenes in cold-smoked salmon. Bacteriocin and its producer might have potential for biopreservation of fishery products against L.monocytogenes.