乙酰丙酸对沙门氏菌诱导性耐酸响应

本实验探究了鼠伤寒沙门氏菌（Salmonella typhimurium）和德尔卑沙门氏菌（S. Derby）在pH值为6.0、5.4的乙酰丙酸、L-乳酸、醋酸和盐酸条件下酸适应后产生的耐酸性。结果表明，酸化剂对沙门氏菌抑菌效果为：乙酰丙酸＞醋酸＞L-乳酸＞盐酸。pH 5.4时，沙门氏菌的诱导耐酸显著高于pH 6.0（P＜0.05）；与其他两种有机酸处理组相比，乙酰丙酸诱导的细菌耐酸性最弱且不同pH值之间差异显著（P＜0.05）。有机酸处理的沙门氏菌细胞内pH值与对照组相比存在差异，其中pH 6.0时乙酰丙酸处理组的鼠伤寒沙门氏菌的细胞内pH值显著高于德尔卑沙门氏菌（P＜0.05）。结果表明沙门氏菌经pH 6.0和pH 5.4的酸适应后会产生耐酸性，而细胞内pH值的变化和诱导耐酸密切相关。

Acid Tolerance in Salmonella Induced by Levulinic Acid

The effects of levulinic acid, L-lactic acid, acetic acid and hydrochloric acid at pH 6.0 and 5.4 on the acid tolerance response of Salmonella typhimurium and S. Derby were investigated. The results showed that the bacteriostatic effects of the four acids were in the following decreasing order: levulinic acid > acetic acid > L-lactic acid > hydrochloric acid. Significantly higher acid tolerance response was induced in Salmonella at pH 5.4 than at pH 6.0 (P < 0.05). The acid tolerance induced by levulinic acid was weaker when compared with the two other organic acids and significantly varied with pH (P < 0.05). The intracellular pH of Salmonella treated with the organic acids was significantly different from that of the control group, and the intracellular pH of S. typhimurium treated with levulinic acid at pH 6.0 was significantly higher than that of S. Derby receiving the same treatment (P < 0.05). The results showed that acidic conditions at pH 6.0 and 5.4 could induce acid tolerance in Salmonella, and the change of intracellular pH was closely related to the acid tolerance response.