Evaluation of fungal consortium lignozyme for biodelignification of agricultural residues

Abstract

AbstractTwo fungal cultures Pleurotus ostreatus (PAU03) and Phanerochaete chrysosporium (MTCC 787) were investigated for their ability to produce ligninolytic enzymes – mainly laccase (Lacc), manganese peroxidase (MnP) and lignin peroxidase (LiP) – under solid‐state fermentation (SSF) conditions, using corn stover as a substrate. Crude LiP, MnP, and Lacc demonstrated specific activity of 11.65 U/mg, 14.9 U/mg and 9.84 U/mg, respectively. The precipitation of crude extract by 70% acetone and subsequent Diethyl amino ethyl (DEAE)‐cellulose ion exchange chromatography resulted in 2.24, 1.23 and 2.60‐fold purification of LiP, MnP and Lac activities, respectively with corresponding specific activities of 26.14 U/mg (LiP), 18.33 U/mg (MnP) and 25.67 U/mg (Lacc) in the partially purified ligninozymes. The latter showed three distinct bands of 40–56 kDA when resolved with sodium dodecyl‐sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). The optimum pH was 6.5 for Lacc and LiP, and 3.0 for MnP, with an optimum temperature of 40 °C. The partially purified laccase had Km of 0.044 mmol L−1/min and Vmax of 222.22 U/mL. Ca2+ and Mn2+ ions increased ligninozyme activity with an increase in concentration from 0.5–5 mmol L−1. Cu2+ ions inhibited ligninozyme activity. The ligninozyme‐assisted pretreatment of wheat straw, rice straw, corn stover, and corn cobs revealed delignification in the range of 70 to 80.3%. The corresponding cellulose and hemicellulose recovery ranged between 58.5 to 65.4% and 38.4 to 47.6%, respectively. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.