Department of Food Science and Human Nutrition, University of Maine, Orono, Maine 04469, USA.
J Food Prot. 2005 Aug;68(8):1635-40. doi: 10.4315/0362-028x-68.8.1635.
The behavior of two strains of Listeria monocytogenes (147 and ATCC 19111) was evaluated at different stages of salmon processing. At lower temperatures of 2, 7, and 11 degrees C, L. monocytogenes survived on dry wood surfaces for at least 3 days without added nutrients but was unrecoverable after 2 days at 22 degrees C. Moisture or minimal nutrients on the wood surface increased viability of L. monocytogenes at all incubation temperatures. When large amounts of nutrients were provided, the recoveries of L. monocytogenes at low temperatures (< or = 11 degrees C) were essentially unchanged over the 3-day holding period, and rapid growth was observed at room temperature. In the presence of natural microflora, L. monocytogenes died off rapidly in seawater within 36 h at room temperature. When held at < or = 11 degrees C, L. monocytogenes lost viability throughout storage but was still detectable after more than 6 days of incubation. In the absence of natural microflora, both strains of L. monocytogenes were static during the holding period at all temperatures. At 2, 7, and 11 degrees C, L. monocytogenes in nonsterile salmon blood-water remained viable even after 6 days of incubation, whereas in sterile blood-water, growth of L. monocytogenes was observed at 7 and 11 degrees C. In the absence of natural microflora, L. monocytogenes grew better than it did in the presence of natural microflora. L. monocytogenes 147 was more competitive with background organisms than was L. monocytogenes ATCC 19111. No L. monocytogenes could be detected in the digestive tract of salmon 3 days after its introduction. The survival pattern of L. monocytogenes in fish digestive tracts was similar, regardless of whether the fish were feeding or not. A noticeable decline in the pathogen was observed as early as 3 h after introduction.
两种李斯特菌（147 株和 ATCC 19111 株）在鲑鱼加工的不同阶段的行为进行了评估。在 2、7 和 11°C 的较低温度下，李斯特菌在没有添加营养物质的干燥木材表面上至少存活 3 天，但在 22°C 下 2 天后无法恢复。木材表面的水分或最少营养物质增加了所有培养温度下李斯特菌的生存能力。当提供大量营养物质时，在低温（≤11°C）下李斯特菌的回收率在 3 天的保持期内基本不变，并且在室温下观察到快速生长。在存在天然微生物群的情况下，李斯特菌在室温下的海水中在 36 小时内迅速死亡。当保持在≤11°C 时，李斯特菌在整个储存过程中失去活力，但在超过 6 天的孵育后仍可检测到。在没有天然微生物群的情况下，两种李斯特菌在所有温度下的保持期内均处于静止状态。在 2、7 和 11°C 下，即使在孵育 6 天后，非无菌鲑鱼血液 - 水中的李斯特菌仍保持活力，而在无菌血液 - 水中，7 和 11°C 下观察到李斯特菌的生长。在没有天然微生物群的情况下，李斯特菌的生长优于存在天然微生物群的情况。147 株李斯特菌比 ATCC 19111 株更能与背景生物竞争。在鲑鱼被引入 3 天后，其消化道中无法检测到李斯特菌。无论鲑鱼是否在进食，李斯特菌在鱼消化道中的存活模式都相似。在引入后 3 小时即可观察到病原体明显下降。
