Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent, Belgium.
Food Microbiol. 2011 Aug;28(5):869-72. doi: 10.1016/j.fm.2010.12.002. Epub 2010 Dec 10.
Previous study showed that repetitive mild decontamination treatments with intense light pulses (ILP) and lactic acid (LA) can induce increased resistance in surviving pathogenic cells. Research has evaluated the potential of increased resistance to enhance the persistence of resistant variants of Listeria monocytogenes and Escherichia coli O157:H7 under suboptimal growth conditions. Growth of resistant variants and parental strains was determined by optical density (OD) measurements in nutrient broths with different pH values and NaCl concentration, at low temperature. The real lag phase was calculated, and results indicated that intense light pulses (ILP) resistant variants needed longer time to initiate growth compared to their parental strains, for both L. monocytogenes and E. coli O157:H7 when incubated at 7 °C and 10 °C, respectively. These selected variants were of the similar resistance towards heat and low pH (no cross-tolerance). Nevertheless, lactic acid (LA) resistant variant of L. monocytogenes was cross-protected when exposed to low pH, but not when treated with heat.
先前的研究表明，使用高强度光脉冲（ILP）和乳酸（LA）进行重复轻度消毒处理可以诱导存活的病原细胞产生更高的抗性。研究已经评估了增加抗性的潜力，以增强李斯特菌和大肠杆菌 O157:H7 的抗性变异体在下限生长条件下的持久性。在不同 pH 值和 NaCl 浓度的营养肉汤中，通过光密度（OD）测量来确定抗性变异体和亲本菌株的生长情况，在低温下进行。计算了实际的迟滞期，结果表明，与亲本菌株相比，高强度光脉冲（ILP）抗性变异体在 7°C 和 10°C 下分别孵育时，需要更长的时间才能开始生长，分别用于单核细胞增生李斯特菌和大肠杆菌 O157:H7。这些选定的变异体对热和低 pH 值具有相似的抗性（无交叉耐受性）。然而，当单核细胞增生李斯特菌的乳酸（LA）抗性变异体暴露于低 pH 值时会受到保护，但在受到热处理时则不会。
