A. This study highlights the role of versatile peroxidases in delignification of biomass for commercial applications.
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B. Among various reagents tested, CuSO4 is identified as most economical inducer of lignin modifying enzymes.
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C. Identified C/N ratio of 20 for preferential induction of versatile peroxidases in the industrial CSML medium.
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D. A mild alkaline peroxide washing step after LME treatment significantly improved cellulose to glucose conversion.
Abstract
Lignin is the most abundant natural source of aromatic polymers in plants. it prevents access to the underlying polymers of cellulose, hemicellulose/xylan for saccharification. Chemical pretreatment methods to remove this lignin barrier have their limitations such as corrosion of equipment, high capital costs, and environmental pollution due to emission of greenhouse gases. As an alternative, lignin modifying enzymes (LME) are being widely tested for delignification. While laccases are proven to break the lignin structure by attacking the phenolic bonds, additional enzymes to break bonds between non-phenolic units are needed. These reactions are commonly mediated by peroxidases such as Lignin peroxidases (LiP) and Versatile peroxidases (VP). Very limited data is available related to production of these very important peroxidases. In the current study, we present efficient production of these peroxidases from a white-rot fungi Pleurotus ostreatus and an optimized pre-treatment process showing an improvement of 20–25% cellulose to glucose conversion efficiency.
