Fenton-reaction-aid selective delignification of lignocellulose by Inonotus obliquus to improve enzymatic saccharification

Abstract

Aiming at improving the efficiency of recovering sugars from wheat straw by the white rot fungus Inonotus obliquus in solid-state fermentation, two Fenton-reaction-aid systems, i.e., one system containing Fenton reaction pretreatment (FRP) and subsequent Inonotus obliquus culture, one system composed of fungal combined treatment with Fe3O4 nanomaterials (NMs), were developed. FRP and NMs improved the fungal growth and degradation efficiency of wheat straw (WS) by regulating ligninolytic enzyme secretion with manganese peroxidase (MnP) (471.0, 359.8 IU g−1), lignin peroxidase (LiP) (108.0, 48.6 IU g−1), and laccase (Lac) (18.0, 13.4 IU g−1) in the FRP group and NMs group within 15 days. Hemicellulose removal on Day 5 and delignification on Day 10 in FRP group (51.3 % and 20.93 %) and NMs group (40.7 % and 12.60 %) were more severe than the control group (19.2 %, 7.37 %). Sugar yield and conversion rate of 10-day-cultured FRP-WS were 228.4 g kg−1 and 37.2 %, 2.1 and 2.6 times higher than that of 10-day-cultured raw WS. Synergism of Fenton reaction and white-rot fungus quickened fermentation period, promoted degradation selectivity, and then subsequent enzymatic hydrolysis. The Fenton-like system established by NMs and I. obliquus made the synergistic system simpler and represented biocompatible chemistry for developing novel microbial cell factories.