Process intensification of indigenous algal-bacterial consortia by ARTP-mutagenized Chlorella for aquaculture wastewater treatment and resource recovery

Achieving stable algal-bacterial treatment in real aquaculture wastewater remains difficult because indigenous microbiota are often viewed as uncontrollable background communities rather than functional components with regulatory potential. In this study, atmospheric and room-temperature plasma (ARTP)-mutagenized Chlorella was used as a biotic selector to assemble indigenous algal-bacterial consortia in real non-sterilized aquaculture wastewater, aiming to intensify nutrient removal, biomass valorization, and carbon-nitrogen metabolic coupling. Among the selected mutants, AMC-2 showed the strongest process-oriented performance, with a final cell density 114% higher than that of the wild type and 32% and 96% increases in the maximum quantum yield of photosystem II photochemistry (F v /F m ) and maximum electron transport rate (ETR max ), respectively. AMC-2 also achieved the highest removal efficiencies for total nitrogen, total phosphorus, and chemical oxygen demand, reaching 89%, 87%, and 87%, respectively, while its volumetric protein, polysaccharide, and lipid yields increased by 78%, 20%, and 128%, respectively. In contrast, AMC-10 showed a storage-oriented phenotype, characterized by stronger pigment accumulation, increased chlorophyll b , and higher intracellular lipid accumulation. Metagenomic analysis revealed that the mutant strains selectively reshaped indigenous bacterial communities, with Roseobacter and Loktanella identified as performance-associated taxa linked to algal growth, nutrient removal, and lipid accumulation. Functional gene profiling further suggested that AMC-2 enhanced treatment performance by coordinating photosynthetic energy utilization, pyruvate supply, carbon skeleton formation, and nitrogen assimilation. These findings suggest that ARTP-mutagenized Chlorella acts as both an improved algal strain and a biotic driver of indigenous algal-bacterial consortia, offering a process-intensification strategy for aquaculture wastewater treatment and resource recovery.