School of Food Sciences and Engineering, South China University of Technology, Guangzhou City, Guangdong Province 510640, China.
Ningbo International Travel Healthcare Center. No. 336 Liuting Street, Haishu District, Ningbo City, Zhejiang Province 315012, China.
Food Res Int. 2020 Apr;130:108963. doi: 10.1016/j.foodres.2019.108963. Epub 2019 Dec 29.
Cronobacter sakazakii is a common foodborne pathogen that can tolerate various stress conditions. Acidic environment is a common stress condition encountered by bacteria in food processing and gastrointestinal digestion, including both inorganic and organic acids. In order to elucidate the Acid Tolerance Response (ATR) of C. sakazakii, we performed high-throughput RNA-seq to compare gene expression under hydrochloric acid and citric acid stresses. In this study, 107 differentially expressed genes (DEGs) were identified in both acids, of which 85 DEGs were functionally related to the regulation of acid tolerance. Multiple layers of mechanisms may be applied by C. sakazakii in response to acid stress: Firstly, in order to reduce excessive intracellular protons, C. sakazakii pumps them out through trans-membrane proteins or consumes them through metabolic reactions. Secondly, under acidic conditions, a large amount of reactive oxygen species and hydroxyl radicals accumulate in the cells, resulting in oxidative damage. C. sakazakii protects cells by up-regulating the antioxidant stress genes such as soxS and madB. Thirdly, C. sakazakii chooses energy efficient metabolic pathways to reduce energy consumption and maintain necessary processes. Finally, genes involved in chemotaxis and motility were differentially expressed to respond to different acidic conditions. This study systematically analyzed the acid-resistant mechanism of C. sakazakii under the stress of organic and inorganic acids, and provided a theoretical basis for better control of its contamination in food.
阪崎克罗诺杆菌是一种常见的食源性致病菌，能够耐受各种应激条件。酸性环境是细菌在食品加工和胃肠道消化过程中经常遇到的一种应激条件，包括无机酸和有机酸。为了阐明阪崎克罗诺杆菌的耐酸应答（ATR），我们进行了高通量 RNA-seq 比较盐酸和柠檬酸胁迫下的基因表达。在这项研究中，在两种酸中鉴定出 107 个差异表达基因（DEGs），其中 85 个 DEGs 与酸耐受调节功能相关。阪崎克罗诺杆菌可能通过多种机制来应对酸应激：首先，为了减少细胞内过多的质子，阪崎克罗诺杆菌通过跨膜蛋白将其泵出或通过代谢反应消耗。其次，在酸性条件下，细胞内会积累大量的活性氧和羟基自由基，导致氧化损伤。阪崎克罗诺杆菌通过上调 soxS 和 madB 等抗氧化应激基因来保护细胞。第三，阪崎克罗诺杆菌选择能量效率高的代谢途径来减少能量消耗并维持必要的过程。最后，参与趋化性和运动的基因差异表达以响应不同的酸性条件。本研究系统分析了阪崎克罗诺杆菌在有机和无机酸胁迫下的耐酸机制，为更好地控制其在食品中的污染提供了理论依据。
