Enhanced lignin biodegradation by consortium of white rot fungi: microbial synergistic effects and product mapping

Tangwu Cui,Yingqun Ma,Weimin Wang,Changzhi Li,Hua Tian,Haiwei Guo,Qiang Fei,Bo Yuan

doi:10.1186/s13068-021-02011-y

Abstract

BackgroundAs one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays.ResultsIn this study, a consortium of white rot fungi composed of Lenzites betulina and Trametes versicolor was employed to enhance the ligninolytic enzyme activity of laccase (Lac) and manganese peroxidase (MnP) under microbial synergism. The maximum enzymatic activity of Lac and MnP was individually 18.06 U mL−1 and 13.58 U mL−1 along with a lignin degradation rate of 50% (wt/wt), which were achieved from batch cultivation of the consortium. The activities of Lac and MnP obtained from the consortium were both improved more than 40%, as compared with monocultures of L. betulina or T. versicolor under the same culture condition. The enhanced biodegradation performance was in accordance with the results observed from scanning electron microscope (SEM) of lignin samples before and after biodegradation, and secondary-ion mass spectrometry (SIMS). Finally, the analysis of heteronuclear single quantum coherence (HSQC) NMR and gas chromatography–mass spectrometry (GC–MS) provided a comprehensive product mapping of the lignin biodegradation, suggesting that the lignin has undergone depolymerization of the macromolecules, side-chain cleavage, and aromatic ring-opening reactions.ConclusionsOur results revealed a considerable escalation on the enzymatic activity obtained in a short period from the cultivation of the L. betulina or T. versicolor due to the enhanced microbial synergistic effects, providing a potential bioconversion route for lignin utilization.

Highlights

As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world
Synergistic effects of White rot fungi (WRF) consortium on ligninolytic enzyme activity and biodegradation The induction of ligninolytic enzymes was shown to be stimulated when culturing a consortium of WRF due to interspecific interactions [29,30,31,32]
The highest enzymatic activities of Lac (18.06 U mL−1) and manganese peroxidase (MnP) (13.58 U mL−1) were achieved in the cultures in the presence of lignin, which reduced the produce time of ligninolytic enzymes over 30%. This finding may be explained that the interspecific interactions between WRFs accelerate a fungal metabolic switch of the formation from primary to secondary metabolites that stimulates the secretion of ligninolytic enzymes [33, 34]

Summary

Introduction

As one of the major components of lignocellulosic biomass, lignin has been considered as the most abundant renewable aromatic feedstock in the world. Comparing with thermal or catalytic strategies for lignin degradation, biological conversion is a promising approach featuring with mild conditions and diversity, and has received great attention nowadays. As the major component of lignocellulose, lignin has drawn great attention due to its aromatic structure characteristic that mainly composed of three phenylpropane units (i.e., sinapyl alcohol, coniferyl alcohol, and p-coumaryl alcohol). As an example for funneling the mixture of monomers by chemo-catalytic methods to produce value-added products, in 2020, Liao et al reported a biorefinery process that converts 78 wt% birch into xylochemicals, which represents one of the major breakthrough towards full utilization of lignin [5, 6]. Great efforts have been made on lignin biodegradation due to its mild condition, diversified choices of microorganisms, and high oxidative potentials. The most common bonds in lignin including β-O-4, β–β, 4-O-5, and 5–5ʹ have all been found to be cleaved by biodegradation methods [8,9,10,11]

Methods

Results

Conclusion