Efficient and synergistic degradation of fluoroquinolones by bacteria and microalgae: Design of environmentally friendly substitutes, risk regulation and mechanism analysis.

ABSTRACT

Fluoroquinolones (FQs) are widely used as antimicrobial agents, and their nonbiodegradable in sewage has become an increasingly concerning. High-biochemical substitutes of FQs were designed with bacteria and microalgae as driving forces of biodegradation, and this is the first study on efficient synergistic degradation of FQs by multiple microorganisms. Among 143 designed FQ substitutes, only one was screened with high biodegradability (increased by 120.51 %), improved functional properties (genotoxicity 13.66 %), less environmental impacts (bio-accumulation -44.81 %), less human health and ecological risk (hepatotoxicity -106.21 %). The complex functional protein with the synergistic degradation effect of bacteria and microalgae was constructed, which proved their synergistic degradation and realized the effect of "1 + 1 > 2″. The best risk regulation scheme determined using molecular dynamics simulation proved the degradation ability of complex functional protein and found the CIP-129 was easy to be degraded in real environment compared with CIP, and the degradation rate increased by 70.42 %. The synthesis path of CIP-129 and CIP were inferred and calculated, and the results showed the Gibbs free energies of three CIP-129 synthetic paths (40.64 a.u.; 40.61 a.u.; 40.65 a.u.) were close to the energy required for the CIP (39.43 a.u.), indicating there was no significant difference in the energy consumption of CIP-129 in laboratory synthesis.