Evaluation of Screened Lignin-degrading Fungi for the Biological Pretreatment of Corn Stover

Yingjie Su,Yang Sun,Xiaoxiao Yu,Gang Wang,Guang Chen,Huan Chen

doi:10.1038/s41598-018-23626-6

Abstract

The biological pretreatment of lignocellulosic biomass is a low-cost and eco-friendly method for facilitating enzymatic hydrolysis. In this study, strains with lignin depletion capability were screened using a high-throughput screening method. Sixty-three strains were screened out and Myrothecium verrucaria secreted three lignin-degrading enzymes simultaneously during the bio-pretreatment process. The activity levels of laccase, lignin peroxidase and manganese peroxidase were 6.61, 0.78 and 1.31 U g−1 dry biomass. The content of lignin in corn stover decreased by 42.30% after bio-pretreatment, and the conversion rate increased by 123.84% during the subsequent saccharification process in comparison with the untreated corn stover. Furthermore, the effects of bio-pretreatment on the structure of corn stover were presented using a scanning electron microscope (SEM), Brunauer-Emmet-Teller (BET), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed that M.V. is a promising lignin-degrading fungus. This research demonstrated an efficient pretreatment approach for enhancing the enzymatic saccharification of corn stover.

Highlights

Chemical energy shortages and increasingly severe environmental pollution have forced people to explore renewable green energy[1]
Barapatre studied the biodegradation of alkali lignin by Aspergillus flavus and Emericella nidulans and found that approximately 14.4% to 21% of alkali lignin reduction occurred in different mediums[19]
Kirk suggested that Phanerochaete chrysosporium (P.C.) efficiently degrades the synthetic lignin in C-sufficient medium, and 22% of lignin decomposed into the total 14C of the 14CO220

Summary

Introduction

Chemical energy shortages and increasingly severe environmental pollution have forced people to explore renewable green energy[1]. Some white rot fungi can simultaneously degrade lignin and polysaccharides, resulting in the loss of carbohydrates, while other white rot fungi can selectively degrade lignin[15]. It is, necessary to choose suitable strains to identify the most potent strain for ideal pretreatment. The potential to improve the ability of lignin depletion and enhance the saccharification of cellulose of the screened strain during the pretreatment process was investigated. The effect of the screened strain on the structure and composition of corn stover during the process of pretreatment were studied.

Methods

Results

Conclusion