RETRACTED: Effect of Rhodospirillum rubrum in effluent on disease resistance, intestinal microbiotaof silver carp

Abstract

Abstract The employment of traditional bait and medicament in freshwater aquaculture causes the frequent occurrence of environmental pollution and disease. Effluent collected after Rhodospirillum rubrum-mediated wastewater treatment could be re-utilized as microbial feeds, medicament, and aquaculture water to culture silver carp. Therefore, a novel integrated system of wastewater treatment using effluent containing R. rubrum that improves yield, increases disease resistance, and enhances the quality of aquaculture water for silver carp culture was proposed and investigated. The yield, whole fish body composition, survival rate, digestive enzymes, nonspecific immune and antioxidant capacity, intestinal microbiota were tested under four groups. Silver carp can grow well in effluent containing R. rubrum (ER). The survival rate, yield, and whole body composition of the ER group were all increased compared to the control group (CK). The biochemical (B vitamin) and other substances in the effluent of R. rubrum enhanced the 20–50% activity of proteases, amylases, lipases, AKP, ACP, phagocytic, SOD, CAT by upregulating the expression of AKP, ACP, SOD, and CAT genes. Theoretical analysis showed that biochemical molecules regulate the expression of these gene and enzyme activities by acting as a signal that stimulates the active center. Furthermore, R. rubrum inhibited Aeromonas hydrophila that increases resistance against fish disease and promotes the growth of intestinal bacteria. Meanwhile, R. rubrum in the effluent also improved the aquaculture water quality. This technology would save the aquaculture water, reduce water pollution and wastewater discharge, and increase the output and disease resistance of silver carp, simultaneously.