This project builds on the original program to investigate the effects and mechanisms of feed additions of sodium propionate (SP) and ethoxyquin (EQ) on fish in the high-fat feed context, and the mechanisms of occurrence of gut microbial translocations in cultured fish on secondary biohazards in aquaculture and aquatic food products, respectively. Firstly, building on the previous finding that the mould inhibitor sodium propionate causes gut damage in fish in the high-fat feed context, it was further shown mechanistically that propionic acid addition leads to gut oxidative stress caused by propionylation of superoxide-dimutase-2 (Sod2), as well as inducing changes in the composition of the gut
microbiota. Furthermore, the negative effects of sodium propionate on the gut epithelial barrier, gut microbiota and susceptible microorganisms in fish in the high-fat dietary background were further clarified on tilapia and rainbow trout. Additionally, the concomitant high dose EQ secondary biological hazards of high fat feeds in China were assessed. The effects of EQ on the gut epithelial barrier, gut microbiota and susceptible microorganisms of tilapia in the high-fat dietary context were clarified, as well as further demonstrating that the addition of SP to the flesh of tilapia fish raised with SP causes secondary biohazards of food for aseptic mice, which provides a theoretical basis for pushing for the enactment of a ban on EQ for feeding purposes in China. The project clarifies the mechanism of fish damage by SP and EQ in a high-fat dietary and the possibility of secondary biohazards, providing theoretical support for the safe production of aquaculture from feed to food. Based on the research results of this project and other research bases of the team, our team was approved to build the National Collection of Livestock and Aquatic Microbes (Beijing), and won the first prize of the 2022-2023 Shennong China Agricultural Science and Technology Award for Scientific Research Achievement.