Area de Nutrición y Bromatología, Escuela Superior y Técnica de Ingeniería Agraria, Universidad de León, 24400-Ponferrada, León, Spain.
Food Microbiol. 2009 Dec;26(8):905-9. doi: 10.1016/j.fm.2009.06.008. Epub 2009 Jun 21.
Data on the ability of chemical poultry decontaminants to induce an acid stress response in pathogenic bacteria are lacking. This study was undertaken in order to compare the survival rates in acid broths of Listeria monocytogenes and Salmonella enterica strains, both exposed to and not exposed to decontaminants. The contribution of the glutamate decarboxylase (GAD) acid resistance system to the survival of bacteria in acid media was also examined. Four strains (L. monocytogenes serovar 1/2, L. monocytogenes serovar 4b, S. enterica serotype Typhymurium and S. enterica serotype Enteritidis) were tested before (control) and after exposure to trisodium phosphate, acidified sodium chlorite, citric acid, chlorine dioxide and peroxyacids (strains were repeatedly passed through media containing increasing concentrations of a compound). Stationary-phase cells (10(8) cfu/ml) were inoculated into tryptic soy broth (TSB) acidified with citric acid (pH 2.7 and 5.0) with or without glutamate (10 mM) added, and incubated at 37 degrees C for 15 min. Survival percentages (calculated from viable colonies) varied from 2.47 +/- 0.67% to 91.93 +/- 5.83%. L. monocytogenes cells previously exposed to acid decontaminants (citric acid and peroxyacids) showed, when placed in acid TSB, a higher (P < 0.05) percentage of survival (average 38.80 +/- 30.52%) than control and pre-exposed to non-acidic decontaminants strains (22.82 +/- 23.80%). Similar (P > 0.05) survival percentages were observed in previously exposed to different decontaminants and control Salmonella strains. The GAD acid resistance system did not apparently play any role in the survival of L. monocytogenes or S. enterica at a low pH. This study demonstrates for the first time that prior exposure to acidic poultry decontaminants increases the percentage of survival of L. monocytogenes exposed to severe acid stress. These results have important implications for the meat industry when considering which decontaminant treatment to adopt.
关于化学禽类清洁剂在诱导病原菌产生酸性应激反应方面的能力的数据尚缺乏。本研究旨在比较经和未经清洁剂处理的单核细胞增生李斯特菌和肠炎沙门氏菌菌株在酸性肉汤中的存活率。还研究了谷氨酸脱羧酶（GAD）酸抗性系统对细菌在酸性介质中存活的贡献。在暴露于三聚磷酸钠、酸化亚氯酸钠、柠檬酸、二氧化氯和过氧酸之前（对照）和之后（4 株李斯特菌血清型 1/2、4b、肠炎沙门氏菌血清型 Typhymurium 和肠炎沙门氏菌血清型 Enteritidis）测试了 4 株菌株（重复通过含有不断增加的化合物浓度的培养基）。将处于静止期的细胞（10（8）cfu/ml）接种到用柠檬酸酸化的胰蛋白胨大豆肉汤（TSB）（pH 2.7 和 5.0）中，添加或不添加谷氨酸（10 mM），并在 37 摄氏度下孵育 15 分钟。（从可存活的菌落计算）存活率从 2.47%±0.67%变化到 91.93%±5.83%。先前暴露于酸性清洁剂（柠檬酸和过氧酸）的单核细胞增生李斯特菌细胞在放入酸性 TSB 时显示出更高的存活率（平均 38.80%±30.52%）（P<0.05），而暴露于非酸性清洁剂的对照和预先暴露于不同清洁剂的菌株（22.82%±23.80%）。先前暴露于不同清洁剂和对照肠炎沙门氏菌菌株的存活百分比相似（P>0.05）。GAD 酸抗性系统在低 pH 下对单核细胞增生李斯特菌或肠炎沙门氏菌的存活似乎没有任何作用。本研究首次证明，先前暴露于酸性禽类清洁剂会增加暴露于严重酸性应激的单核细胞增生李斯特菌的存活率百分比。这些结果对于肉类行业在考虑采用哪种清洁剂处理方法时具有重要意义。
