Enhanced fungal delignification and enzymatic digestibility of poplar wood by combined CuSO4 and MnSO4 supplementation

Biological pretreatment of lignocellulose by white-rot fungi is an environmentally friendly alternative to chemical and physical approaches to enhance enzymatic saccharification. However, inefficient lignin degradation and substantial cellulose consumption during fungal pretreatment can cause low sugar yields. In this study, the combined action of CuSO4 and MnSO4 effectively improved the degree and selectivity of delignification during solid-state fungal pretreatment of poplar wood by Phanerochaete chrysosporium. Compared to pretreatment without this supplementation, a 1.9 fold higher lignin degradation and 2.4 times higher delignification selectivity value were obtained due to the increased and prolonged manganese peroxidase activity. Enzymatic saccharification of supplemented pretreated wood resulted in a 2.9 times higher glucose yield compared to the non-supplemented system. This study has demonstrated that the combined application of Mn2+ and Cu2+ can significantly improve the fungal pretreatment process and that the beneficial effect of Cu2+ on delignification is not restricted to laccase-producing fungi.