Biotransformation of enrofloxacin-copper combined pollutant in aqueous environments by fungus Cladosporium cladosporioides (CGMCC 40504).

The combined pollution of antibiotics and heavy metals in aqueous environments increases the risk of aquatic ecosystem disruption and the complication of pollutant management. Here, a fungus Cladosporium cladosporioides 11 (CC11) isolated from aquaculture pond sediments possessed effective capacities to biotransform the combined pollution of enrofloxacin (ENR) and copper ion (Cu). ENR and Cu were considerably abated by CC11, and the presence of Cu (30 mg/L) promoted the biotransformation efficiency of ENR. The biotranformation of ENR in ENR-Cu co-contamination was associated to ligninolytic enzyme action. The expression of ligninolytic enzymes was enhanced by ENR and ENR-Cu combined pollution. And the increased activities of ligninolytic enzymes confirmed the significant role of enzymatic transformation. Cu played an important role in increasing the expression and activities of ligninolytic enzymes. The expressions of many genes associated with transporters, phosphate assimilation, oxidative phosphorylation, hyperosmotic stress and pectin metabolism were significantly up-regulated when facing Cu-stress, indicating their important roles in determining Cu removal and enhancing Cu-resistance. Additionally, CC11 significantly biotransformed other antibiotic and heavy metal combined pollution. All these results contributed to the applications of CC11 in aqueous environments.