Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable
advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance
of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone
using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes
by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors
responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/
L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from
glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of
microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69%
treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively.
The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone
by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are
responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might
insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation.
These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using
a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable
products.peer-reviewe