Sarafloxacin hydrochloride exposure disrupts gut microbiota and increases shrimp susceptibility to Vibrio anguillarum infection

Abstract

Owing to the rising incidence of disease in intensive farming, prophylactic antibiotics have often been used to avoid shrimp diseases and economic losses. However, the efficiency of prophylactic antibiotics is questionable, while the underlying mechanism is unclear. Here, we used the most aquacultured shrimp Litopenaeus vannamei as a model to interrogate the effect of prophylactic sarafloxacin hydrochloride (SAR) on susceptibility to Vibrio anguillarum (a pathogen that causes acute hepatopancreatic necrosis disease) infection. SAR exposure significantly retarded shrimp growth, and caused faster and higher mortality in response to subsequent V. anguillarum infection. In addition, SAR exposure disrupted the gut microbiota, including reduced diversity, altered structure, accelerated turnover rate, instabilized gut network, increased beta-dispersion, pathogenic potential and immune activity. In addition, SAR exposure increased the proportion of stochastic processes in controlling the gut microbiota, in parallel with attenuated homogenizing selection, which could compromise host selection on the invading pathogen. The functional pathways involved in carbohydrate metabolism, lipid metabolism and signal transduction remarkably increased in SAR exposure shrimp, which could be attributed to the allocation of energy to immunity in facing pathogen invasion. We screened 30 infection-discriminatory taxa after removal of the ontogenic changes in gut microbiota. Our diagnosis model correctly differentiated (84.8% overall accuracy) SAR exposure and/or infection in shrimp, with 83.3% accuracy at the onset of infection. Collectively, our findings provide soild evidence that prophylactic antibiotics induce shrimp disease susceptibility from an ecologcial viewpoint.