Influence of the salt concentration on action mechanisms of natamycin against microorganisms of importance in food manufacture

Abstract The objective of this study was to evaluate the influence of salt concentration on action of natamycin on important microorganisms in food manufacturing as this preservative has been used in immersion baths in several dairy products in the country. Strains of Candida albicans, Escherichia coli and Staphylococcus aureus were inoculated at different saline and peptone water concentrations and received natamycin treatments. These solutions were maintained at 12 °C and the behavior of the microorganisms evaluated at 0, 24 and 48 hours (T0, T1 and T2). Each microorganism was assessed in isolation as well as the association of C. albicans and E. coli. Under the conditions proposed by the research, it was possible to conclude that 0.025% natamycin has no efficacy on C. albicans inoculated at saline concentrations below 5%. The results obtained in E. coli counts suggest that natamycin may interfere with its development even at concentrations that may be considered low (0.1%) and at salinity conditions of 7.5% to 10%. The association of natamycin with sodium chloride potentiates its antimicrobial action, which can represent an economy and its use is amplified by the industries.摘要 本研究旨在评估盐浓度对纳他霉素（natamycin）作用于食品工业重要微生物的影响——由于该防腐剂已在我国多款乳制品的浸渍处理浴中得到应用。研究选取白色念珠菌（Candida albicans）、大肠杆菌（Escherichia coli）与金黄色葡萄球菌（Staphylococcus aureus）菌株，在不同盐浓度与蛋白胨水浓度条件下完成接种，并施加纳他霉素处理。将上述溶液维持于12℃环境，分别于0、24、48小时（记为T0、T1、T2）监测微生物的生长情况。每种微生物均单独开展测试，同时也设置了白色念珠菌与大肠杆菌的混合测试体系。在本研究设定的实验条件下，可得出如下结论：当盐浓度低于5%时，0.025%的纳他霉素对白色念珠菌无抑菌效能。大肠杆菌的计数结果显示，即便在纳他霉素浓度较低（0.1%）以及盐浓度为7.5%至10%的条件下，纳他霉素仍可对其生长产生抑制作用。纳他霉素与氯化钠复配可增强其抗菌活性，这既能为工业生产节约成本，也可扩大该防腐剂的应用范围。