Study on the antioxidant defense of Pacific oysters (Crassostrea gigas) against sulfonamide antibiotics

Abstract

In this study, the impact of four sulfonamide antibiotics on the antioxidant defense mechanisms of the Pacific oyster (Crassostrea gigas) were detected. The exposure concentrations were set at 5 μg/L and 500 μg/L, based on the concentrations of sulfonamide antibiotics that have been investigated in the marine environment. The experiment was conducted at 48-h and 14-day exposure to the antibiotics, and bacterium stimulation by Vibrio parahaemolyticus after the exposure. The results showed that the oysters exhibited varying degrees of bioaccumulation for different sulfonamide antibiotics, though all bioconcentration factors (BCFs) remained below the threshold of 1000 (L/kg). However, given that oysters in natural environments are exposed to these antibiotics for significantly longer durations than in this experiment, the potential health risks associated with consuming sulfonamide-contaminated oysters cannot be overlooked. Additionally, research findings demonstrated that sulfonamide antibiotics trigger unique antioxidative responses within specific oyster tissues. These compounds catalyze notable shifts in SOD, CAT, and GPx enzyme activities, alongside MDA levels, with variations distinctly observed across different tissue types. The biotoxic effect of antibiotics on the oyster gills was lower than that on the hepatopancreas. The low concentrations of sulfonamide antibiotics exposure could induce antioxidant defences in the gills, but did not cause severe oxidative damage. While, high concentrations exposure could cause hepatopancreas oxidative damage. Among the four sulfonamide antibiotics, the potential biotoxic effect of sulphadoxine (SDX) was the highest, followed by sulfamethazine (SMT), sulfamonomethoxine (SMM), and sulfamethoxazole (SMX), while the biological oxidative stress responses of oysters to SMM and SMT were earlier than those of SMX and SDX.