Center for Meat Safety & Quality, Food Safety Cluster, Dept. of Animal Sciences, 1171 Campus Delivery, Colorado State Univ., Fort Collins, CO 80523-1171, USA.
J Food Sci. 2010 Sep;75(7):M444-8. doi: 10.1111/j.1750-3841.2010.01744.x. Epub 2010 Sep 2.
This study used various approaches to investigate the potential association of autoinducer-2 (AI-2) presence with thermal and acid resistance of Salmonella cultures. Salmonella Thompson strains RM1987N (luxS-positive; AI-2 positive) and RM1987NLUX (luxS-negative; AI-2 negative) were exposed to 55 °C (6 h) in Luria-Bertani (LB) broth, while the luxS-negative S. Thompson strain and a Salmonella Typhimurium luxS-positive strain were exposed to 55 °C in AI-2-positive or -negative preconditioned (PC) media derived from S. Thompson and Escherichia coli O157:H7 luxS-positive and -negative strains. In addition, the luxS-negative S. Thompson strain was subjected to pH 3.5 PC media (35 °C, 6 h) with or without AI-2 activity, and acid-adapted or nonadapted S. Thompson strains were exposed to pH 3.0 LB broth (35 °C, 6 h). Surviving bacterial populations during exposure to 55 °C LB were not different between luxS-negative and -positive S. Thompson strains. In addition, heating at 55 °C of the luxS-negative S. Thompson strain in AI-2-positive and -negative PC media resulted in similar (P ≥ 0.05) survivor counts. Furthermore, surviving cell counts of S. Typhimurium (luxS-positive) in 55 °C AI-2-positive PC media were not different (P ≥ 0.05) than those in AI-2 negative PC media. No differences in surviving cell counts of the luxS-negative S. Thompson strain was found when exposed to pH 3.5 AI-2-positive and -negative PC media. Also, survivors of acid-adapted or nonadapted cells of luxS-negative and -positive S. Thompson strains were not different following exposure to pH 3.0 LB. The results indicated that, under the conditions of this study, AI-2-based quorum sensing did not appear to be associated with heat and acid resistance of Salmonella.
本研究采用多种方法研究了群体感应信号分子 AI-2 的存在与沙门氏菌耐热和耐酸能力之间的潜在关联。将沙门氏菌 Thompson 菌株 RM1987N（luxS 阳性；AI-2 阳性）和 RM1987NLUX（luxS 阴性；AI-2 阴性）暴露于 LB 肉汤中 55°C（6 h），而 luxS 阴性的 S. Thompson 菌株和 Salmonella Typhimurium luxS 阳性菌株则分别暴露于 AI-2 阳性或阴性的条件培养基中，这些条件培养基是由 S. Thompson 和 Escherichia coli O157:H7 luxS 阳性和阴性菌株衍生而来。此外，将 luxS 阴性的 S. Thompson 菌株暴露于 pH 3.5 的条件培养基（35°C，6 h）中，条件培养基中存在或不存在 AI-2 活性，并对适应酸或未适应酸的 S. Thompson 菌株进行 pH 3.0 的 LB 肉汤（35°C，6 h）暴露。在 55°C LB 中暴露期间，luxS 阴性和阳性 S. Thompson 菌株的存活细菌数量没有差异。此外，在 AI-2 阳性和阴性 PC 培养基中加热 55°C 的 luxS 阴性 S. Thompson 菌株导致相似的（P ≥ 0.05）存活菌数。此外，在 AI-2 阳性 PC 培养基中，55°C 的 Salmonella Typhimurium（luxS 阳性）的存活细胞计数与 AI-2 阴性 PC 培养基中的存活细胞计数没有差异（P ≥ 0.05）。在暴露于 pH 3.5 的 AI-2 阳性和阴性 PC 培养基中，luxS 阴性 S. Thompson 菌株的存活细胞计数没有差异。此外，在暴露于 pH 3.0 的 LB 后，luxS 阴性和阳性 S. Thompson 菌株的适应酸和未适应酸细胞的存活菌没有差异。结果表明，在本研究的条件下，基于 AI-2 的群体感应似乎与沙门氏菌的耐热和耐酸能力无关。
