Ligninolytic enzyme activity and removal efficiency of pharmaceuticals in a water matrix by fungus Rhizopus sp. Isolated from cassava

Abstract

ABSTRACT Residual amounts of pharmaceutical compounds (PhCs) and by-products are continually released into surface water with effluents from conventional wastewater treatment plants (WWTPs). This study evaluated the ability of fungal isolate to remove selected PhCs [carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBP)] from wastewater. The fungus used was Rhizopus sp. which was isolated from tuberous roots of cassava (Manihot esculenta). The isolate exhibited an important removal efficiency up to 100% and this was linked to ligninolytic enzymatic activity for lignin peroxidase (15.29 ± 2.69U/L) and manganese peroxidase (85.22 ± 4.26U/L), except laccase. This activity was optimum on day 9 of treatment. PhC metabolites were identified during the experiment revealing the existence of a biotransformation process catalysed by the isolated fungus. The disappearance of PhCs was attributed to their biosorption and biotransformation. However, it was not possible to establish a relationship between the ligninolytic enzymatic activity and the removal efficiency, which leads to the conclusion that there are other fungal metabolites which also play an important role in the biotransformation and biodegradation of the selected PhCs.