Kim Jong H, Tam Christina C, Chan Kathleen L, Cheng Luisa W, Land Kirkwood M, Friedman Mendel, Chang Perng-Kuang
Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, USDA-ARS, 800 Buchanan St., Albany, CA 94710, USA.
Department of Biological Sciences, University of the Pacific, 3601 Pacific Avenue, Stockton, CA 95211, USA.
Foods. 2021 Sep 2;10(9):2073. doi: 10.3390/foods10092073.
The fungal antioxidant system is one of the targets of the redox-active polyene antifungal drugs, including amphotericin B (AMB), nystatin (NYS), and natamycin (NAT). Besides medical applications, NAT has been used in industry for preserving foods and crops. In this study, we investigated two parameters (pH and food ingredients) affecting NAT efficacy. In the human pathogen, , NAT (2 to 16 μg mL) exerted higher activity at pH 5.6 than at pH 3.5 on a defined medium. In contrast, NAT exhibited higher activity at pH 3.5 than at pH 5.6 against foodborne fungal contaminants, , , and , with being the most sensitive. In commercial food matrices (10 organic fruit juices), food ingredients differentially affected NAT antifungal efficacy. Noteworthily, NAT overcame tolerance of the signaling mutants to the fungicide fludioxonil and exerted antifungal synergism with the secondary metabolite, kojic acid (KA). Altogether, NAT exhibited better antifungal activity at acidic pH against foodborne fungi; however, the ingredients from commercial food matrices presented greater impact on NAT efficacy compared to pH values. Comprehensive determination of parameters affecting NAT efficacy and improved food formulation will promote sustainable food/crop production, food safety, and public health.
真菌抗氧化系统是氧化还原活性多烯类抗真菌药物的作用靶点之一，这些药物包括两性霉素B（AMB）、制霉菌素（NYS）和纳他霉素（NAT）。除了医学应用外，NAT还被用于食品和农作物的工业保鲜。在本研究中，我们调查了影响NAT疗效的两个参数（pH值和食品成分）。在人类病原体中，在特定培养基上，NAT（2至16μg/mL）在pH 5.6时比在pH 3.5时表现出更高的活性。相比之下，NAT在pH 3.5时比在pH 5.6时对食源性真菌污染物（ 、 、 和 ）表现出更高的活性，其中 最为敏感。在商业食品基质（10种有机果汁）中，食品成分对NAT的抗真菌效果有不同影响。值得注意的是，NAT克服了 信号突变体对杀菌剂咯菌腈的耐受性，并与次生代谢产物曲酸（KA）发挥抗真菌协同作用。总体而言，NAT在酸性pH条件下对食源性真菌表现出更好的抗真菌活性；然而，与pH值相比，商业食品基质中的成分对NAT疗效的影响更大。综合测定影响NAT疗效的参数并改进食品配方将促进可持续的食品/作物生产、食品安全和公众健康。
