Purification effect of algae and immobilized bacteria combination system in aquaculture wastewater treatment with targeted removal of pathogenic Vibrio and antibiotic resistance genes

Abstract

With development of the mariculture industry and increasing seafood demand, mariculture has become an intensive, high-density, and high-yield farming model. The resulting high nitrogen and phosphorus loads pose serious threats to the environment and economy. This study developed an innovative bacteria-algae symbiotic system (BI+A) combining functional nitrogen-removing bacteria isolated from Penaeus albus culture ponds with Tetraselmis subcordiformis to address these critical issues. The bio-system demonstrated exceptional remediation capabilities for Litopenaeus vannamei tail water treatment, achieving >93 % ammonium removal and 67–95 % reduction of key nutrients including total nitrogen and phosphorus within 4 days. Notably, the technology effectively mitigated biological risks through 97–99 % elimination of pathogenic Vibrio parahaemolyticus and Metschnikowia bicuspidata, while significantly reducing total antibiotic resistance genes (ARGs) abundance by 57.9 % with complete removal of critical β-lactam resistance determinants. The integrated bio-remediation approach provide an effective solution for the treatment of mariculture tail water, which helps to solve the problems of environmental pollution and ecological damage faced by the aquaculture industry. It is of great significance for promoting the sustainable development of the mariculture industry.

With development of the mariculture industry and increasing seafood demand, mariculture has become an intensive, high-density, and high-yield farming model. The resulting high nitrogen and phosphorus loads pose serious threats to the environment and economy. Furthermore, numerous microorganisms in tail water, particularly pathogenic bacteria, and antibiotic resistance bacteria and antibiotic resistance genes (ARGs) in the breeding environment and cultured organisms, endanger the surrounding population and marine ecosystems. To effectively treat tail water, this study combined treatment technology based on bacteria and algae, using isolated strains with nitrogen-removal function from a Penaeus albus culture tail water pond, and cultured the dominant bacteria groups. A semi-fixed bacteria–algal bio-system (BI+A) was then established with Tetraselmis subcordiformis, and removal rates of nutrients, pathogenic bacteria, and ARGs from Litopenaeus vannamei tail water were investigated. BI+A efficiently removed nutritive substances in tail water, particularly nitric and total nitrogen, and active and total phosphorus; after 4 d of operation, the NH₄⁺ removal efficiency reached 93.45 %. The total nitrogen, active phosphorus, total phosphorus, and chemical oxygen demand removal efficiency reached 67 %, 95 %, 51 %, and 75.2 %, respectively. Pathogenic Vibrio (Vibrio parahaemolyticus) and pathogenic yeast (Metschnikowia bicuspidata) removal rates were 97 % and 99.1 %, respectively. The total abundance of ARGs decreased by 57.9 %, and the ARGs of sulfonamides and glycopeptides in ARGs were significantly removed, with removal rates of 85 %, 85 %, and 98 % for sulfa sul, 1sul2, and glycopeptide vanAB, respectively. The cephalosporins OXA-131 removal rate was 100 %.