Bio-removal Of Fluoroquinolones And Sulfamethoxazole Under The Co-culture Of Pycnoporus Sanguineus And Phanerochaete Chrysosporium

The recalcitrant presence of fluoroquinolones and sulfonamides antibiotics in aquatic environments pose a potential threat to the public health.The removals of ciprofloxacin?CIP?,norfloxacin?NOR?,sulfamethoxazole?SMX?and their mixtures and their potential biotransformation mechanisms under the pure culture and co-culture of Pycnoporus sanguineus and Phanerochaete chrysosporium were investigated in this work.The main results are as followings:1)The removal efficiencies of CIP,NOR and SMX under the pure culture of P.chrysosporium and P.sanguineus in Kirk medium were higher than that in potato dextrose broth.The removal efficiencies of CIP,NOR,SMX and their mixtures within 2 d were 98.5%,96.4%,100%and 100%under the pure culture of P.sanguineus in Kirk medium,respectively.However,the removal efficiencies of CIP,NOR,and SMX within 8 d were 64.5%,73.2%,63.3%under the pure culture of P.chrysosporium,respectively.CIP,NOR and SMX could be completely removed within 8 d under the co-culture of P.chrysosporium and P.sanguineus.2)CIP,NOR and SMX in their mixtures could be completely removed within 24h when 0.1064 g·L^-1 tween 80 were added to the pure culture of P.sanguineus,while the removal efficiencies of CIP,NOR and SMX in their mixtures were significantly reduced when adding tween 80 to the pure culture of P.chrysosporium,which indicated that tween 80 improved the removal rate of antibiotics by P.sanguineus.The addition of tween 80 to the co-culture system enhanced the removal rate of CIP and NOR in the mixtures,while had no effect on the removal rate of SMX in the mixtures.3)Biosorption played an important role in bio-removal of antibiotics by P.chrysosporium,while the main bioremoval route of antibiotics under the pure culture and co-culture of P.sanguineus was biotransformation.Enzymes activities and inhibitor results indicated that laccase and cytochrome P450 system might play roles in the biotransformation of CIP,NOR and SMX,while manganese peroxidase could only participate in the biotransformation of SMX.There were three proposed transformation pathways of CIP and NOR under the pure culture of P.chrysosporium:defluorination or dehydration,decarboxylation and oxidation of the piperazinyl substituent.However,in addition to the above three transformation pathways,the transformation pathways of CIP and NOR under the pure culture and co-culture of P.sanguineus might also include deethylation and demethylation at position N₁.Although the removal rate of antibiotics under the co-culture was lower than that under the pure culture of P.sanguineus,the biotoxicity of metabolites when dealing with NOR and SMX under co-culture were lower.The above studies can not only efficiently bio-remove fluoroquinolones and sulfonamides,but also provide a more environmentally friendly strategies to bio-eliminate these antibiotics.