Busch S V, Donnelly C W
Department of Animal Science, University of Vermont, Burlington 05405.
Appl Environ Microbiol. 1992 Jan;58(1):14-20. doi: 10.1128/aem.58.1.14-20.1992.
The ability of the divalent cations magnesium, iron, calcium and manganese; yeast extract; pyruvate; catalase; and the carbohydrates glucose, lactose, sucrose, esculin, fructose, galactose, maltose, and mannose to facilitate repair of heat-injured Listeria monocytogenes and Listeria innocua was evaluated. Listeria populations were injured by heating at 56 degrees C for 50 min. To determine the effects on repair, Trypticase soy broth (TSB) was supplemented with each medium component to be evaluated. Repair occurred to various degrees within 5 h in TSB supplemented with glucose, lactose, sucrose, yeast extract, pyruvate, or catalase. Chelex-exchanged TSB was supplemented with divalent cations; magnesium and iron cations were found to have a role in repair. Listeria repair broth (LRB) was formulated by utilizing the components that had the greatest impact upon repair. When incubated in LRB, heat-injured Listeria cells completed repair in 5 h. After the repair, acriflavin, nalidixic acid, and cycloheximide were added to LRB to yield final concentrations identical to those of the selective enrichment broths used in the procedures of the Food and Drug Administration and the U.S. Department of Agriculture. The efficacy of LRB in promoting repair and enrichment of heat-injured Listeria cells was compared with that of existing selective enrichment broths. Repair was not observed in the Food and Drug Administration enrichment broth, Listeria enrichment broth, or University of Vermont enrichment broth. The final Listeria populations after 24 h of incubation in selective enrichment media were 1.7 x 10(8) to 9.1 x 10(8) CFU/ml; populations in LRB consistently averaged 2.5 x 10(11) to 8.2 x 10(11) CFU/ml.
评估了二价阳离子镁、铁、钙和锰；酵母提取物；丙酮酸；过氧化氢酶；以及碳水化合物葡萄糖、乳糖、蔗糖、七叶苷、果糖、半乳糖、麦芽糖和甘露糖促进热损伤的单核细胞增生李斯特菌和无害李斯特菌修复的能力。将李斯特菌菌液在56℃加热50分钟使其受到损伤。为了确定对修复的影响，在胰蛋白胨大豆肉汤（TSB）中添加每种待评估的培养基成分。在添加了葡萄糖、乳糖、蔗糖、酵母提取物、丙酮酸或过氧化氢酶的TSB中，5小时内不同程度地发生了修复。用螯合树脂处理过的TSB中添加了二价阳离子；发现镁离子和铁离子在修复过程中起作用。利用对修复影响最大的成分配制了李斯特菌修复肉汤（LRB）。热损伤的李斯特菌细胞在LRB中培养时，5小时内完成修复。修复后，向LRB中添加吖啶黄素、萘啶酸和环己酰亚胺，使其终浓度与美国食品药品监督管理局和美国农业部程序中使用的选择性增菌肉汤相同。将LRB促进热损伤李斯特菌细胞修复和增菌的效果与现有的选择性增菌肉汤进行了比较。在美国食品药品监督管理局增菌肉汤、李斯特菌增菌肉汤或佛蒙特大学增菌肉汤中未观察到修复现象。在选择性增菌培养基中培养24小时后的最终李斯特菌菌数为1.7×10⁸至9.1×10⁸CFU/ml；LRB中的菌数始终平均为2.5×10¹¹至8.2×10¹¹CFU/ml。
