Unraveling the key driving factors involved in cometabolism enhanced aerobic degradation of tetracycline in wastewater

Cometabolism has shown great potential in increasing the engineering feasibility of microalgae-based bio-technologies for the aerobic treatment of antibiotics-polluted wastewaters. Yet, the underlying mechanisms involved in improved microalgal performance remain unknown. In this study, we incorporated transcriptomics, gene network analysis, and enzymatic activities with cometabolic pathways of tetracycline (TC) by Chlorella pyrenoidosa to identify the key driving factors. The results demonstrated that cometabolism constructed a metabolic enzymes-photosynthetic machinery to improve the electron transport chain and activities of catalytic enzymes, which resulted in subsequent 100% removal of TC. Coupling formation dynamics of the intermediates with roles of identified metabolic enzymes, degradation of TC can be induced by de/hydroxylation, de/hydro-genation, bond-cleavage, decarboxylation, and deamination. Evaluation of 18 antibiotics' removal in reclaimed water showed cometabolism decreased the total concentrations of these antibiotics from 495.54 ng L-1 to 221.80 ng L-1. Our findings not only highlight the application potential of cometabolism in increasing engi-neering feasibility of microalgal degradation of antibiotics from wastewaters, but also provide the unique in-sights into unraveling the black-box of cometabolisms in aerobic biodegradation.

Automated summary

This study investigated the key driving factors involved in the cometabolic degradation of tetracycline by Chlorella pyrenoidosa. The results showed that cometabolism improved the performance of microalgae by enhancing the electron transport chain and catalytic enzyme activities. The cometabolic pathways involved de/hydroxylation, de/hydrogenation, bond cleavage, decarboxylation, and deamination. The study also demonstrated that cometabolism reduced the concentration of various antibiotics in reclaimed water.