Marine Heterotrophic Nitrification-Aerobic Denitrification Process Treating Mariculture Wastewater: Microbiome and Resistome Responses to Multiantibiotic Stresses

Marine heterotrophic nitrification-aerobicdenitrificationbacteria can be augmented to effectively treat mariculture wastewatercontaining multiple antibiotics. Efficient treatment of mariculture wastewater is essentialto thesustainable development of the mariculture industry, yet a high salinityand multiple antibiotics contained therein pose a serious challengeto biological treatment. In this study, marine heterotrophic nitrification-aerobicdenitrification (MHNAD) bacteria were successfully augmented for mariculturewastewater treatment, and their multiantibiotic (i.e., ampicillin-tetracycline-sulfamethoxazole(ATS)) resistance mechanisms were deciphered through the co-occurrencepatterns of microbiome and resistome. Up to an ATS dose of 36 mg & BULL;L-1, MHNAD bacteria exhibited a strong antibiotic resistance,achieving high organic and nitrogen removal efficiencies of 95.2 and100%, respectively. Meanwhile, more extracellular polymeric substanceswere produced to enhance the bacterial resistance to antibiotics.The MHNAD genus, Klebsiella, invariably dominatedthe bioreactor (mean relative abundance of 34.1%) and mainly accountedfor pollutant removals. The absolute abundance of total antibioticresistance genes increased by 21.7 folds at an ATS dose of 72 mg & BULL;L-1, as compared to that without ATS. The abundance of sul1, tetQ, or intI1 waspositively correlated with the ATS dose, and Klebsiella was strongly correlated with sul1, tetQ, tetX, and bla (TEM).This study proposes a novel process for mariculture wastewater treatmentthrough augmentation of MHNAD bacteria under multiantibiotic stresses.