Molecular characterization and overexpression of mnp6 and vp3 from Pleurotus ostreatus revealed their involvement in biodegradation of cotton stalk lignin.

Yan Wang,Xi Cheng,Muhammad Abdullah,Guoqing Li,Dahui Li,Fan Nie,Yongping Cai,Xiaoyu Jiao,Yi Lin

doi:10.1242/bio.036483

Abstract

ABSTRACTFungal secretory heme peroxidase (Class II POD) plays a significant role in biomass conversion due to its lignin-degrading activity. In this study, genome-wide identification and bioinformatics were performed to analyze Pleurotus ostreatus peroxidases (PoPODs). A total of six manganese peroxidases (MnPs) and three versatile peroxidases (VPs) were obtained. Bioinformatics analysis and qRT-PCR showed that P. ostreatus mnp6 (Pomnp6) and P. ostreatus vp3 (Povp3) could be involved in lignin degradation. Both Pomnp6 and Povp3 transgenetic fungi showed significantly increased lignin degradation of cotton stalks. 1H-NMR revealed that Pomnp6 and Povp3 may preferentially degrade S-lignin in cotton stalks and mainly break β-O-4′ bond linkages and hydroxyl. These results support the possible utility of Pomnp6 and Povp3 in natural straw resources and development of sustainable energy.

Highlights

The main carbohydrates in crop straw are lignin, cellulose and hemicellulose
Phylogenetic analysis of Pleurotus ostreatus peroxidases (PoPODs) Nine putative peroxidase genes (PoPODs) were obtained from the Joint Genome Institute (JGI) and other basidiomycetes POD gene sequence data was obtained from National Center for Biotechnology Information (NCBI) (Alfaro et al, 2016; Castanera et al, 2016; Riley et al, 2014)
Nine ligninolytic peroxidase genes were screened from P. ostreatus

Summary

Introduction

The main carbohydrates in crop straw are lignin, cellulose and hemicellulose. Lignin is a heterogeneous aromatic polymer; the major C6–C3 ( phenylpropanoid) units of lignin are connected by ether and carbon-carbon linkages, such as β-O-4′, 4-O-5′, β-β′, β-1′, β-5′ and 5-5′ (Kumar et al, 2009). The bio-conversion of plant lignocellulose to glucose is an important part of second generation biofuel production. Due to the complex and heterogeneous structures of lignin, straw resources are difficult to fully utilize (Lan et al, 2011). Previous research has shown that white-rot fungi could break down lignin polymers with their extracellular oxidases, indicating great significance for the application of biomass conversion (Bugg et al, 2011).

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