Sandal reactive dyes decolorization and cytotoxicity reduction using manganese peroxidase immobilized onto polyvinyl alcohol-alginate beads

Background: Fungal manganese peroxidases (MnPs) have great potential as bio-remediating agents and can be used continuously in the immobilized form like many other enzymes. Results: In the present study, purified manganese peroxidase (MnP) enzyme isolated from Ganoderma lucidum IBL-05 was immobilized onto polyvinyl alcohol-alginate beads and investigated its potential for the decolorization and detoxification of new class of reactive dyes and textile wastewater. The optimal conditions for MnP immobilization were 10% (w/v) PVA, 1.5% sodium alginate,3% boric acid and 2% CaCl2 solution. The optimum pH, temperature and kinetic parameters (K-m and V-max) for free and immobilized MnP were found to be significantly altered after immobilization. The immobilized MnP showed high decolorization efficiency for Sandal reactive dyes (78.14-92.29%) and textile wastewater (61-80%). Reusability studies showed that after six consecutive dye decolorization cycles, the PVA coupled MnP retained more than 60% of its initial activity (64.9% after 6th cycle form 92.29% in 1st cycle) for Sandal-fix Foron Blue E2BLN dye. The water quality assurance parameters (BOD, COD and TOC) and cytotoxicity (haemolytic and brine shrimp lethality tests) studies before and after treatment were employed and results revealed that both the dyes aqueous solution and textile wastewater were cytotoxic that reduced significantly after treatment. Conclusions: The decolorization and cytotoxicity outcomes indicated that immobilized MnP in PVA-alginate beads can be efficiently exploited for industrial and environmental applications, especially for remediation of textile dyes containing wastewater effluents.