Heterozygous diploid structure of Amorphotheca resinae ZN1 contributes efficient biodetoxification on solid pretreated corn stover

Xia Yi,Fengxian Hu,Lei Zhang,Yanqing He,Zhihua Zhou,Qiuqiang Gao,Jie Bao,Jian Zhang,Shihui Yang,Gen Zou,Xia Wang

doi:10.1186/s13068-019-1466-z

Abstract

BackgroundFast, complete, and ultimate removal of inhibitory compounds derived from lignocellulose pretreatment is the prerequisite for efficient production of cellulosic ethanol and biochemicals. Biodetoxification is the most promising method for inhibitor removal by its unique advantages. The biodetoxification mechanisms of a unique diploid fungus responsible for highly efficient biodetoxification in solid-state culture was extensively investigated in the aspects of cellular structure, genome sequencing, transcriptome analysis, and practical biodetoxification.ResultsThe inborn heterozygous diploid structure of A. resinae ZN1 uniquely contributed to the enhancement of inhibitor tolerance and conversion. The co-expression of gene pairs contributed to the enhancement of the degradation of lignocellulose-derived model inhibitors. The ultimate inhibitors degradation pathways and sugar conservation were elucidated by microbial degradation experimentation as well as the genomic and transcriptomic sequencing analysis.ConclusionsThe finding of the heterozygous diploid structure in A. resinae ZN1 on biodetoxification took the first insight into the global overview of biodetoxification mechanism of lignocellulose-derived inhibitors. This study provided a unique and practical biodetoxification biocatalyst of inhibitor compounds for lignocellulose biorefinery processing, as well as the synthetic biology tools on biodetoxification of biorefinery fermenting strains.

Highlights

Fast, complete, and ultimate removal of inhibitory compounds derived from lignocellulose pretreatment is the prerequisite for efficient production of cellulosic ethanol and biochemicals
When submerged liquid biodetoxification is conducted in enzymatic hydrolysate, the cellulase enzyme activity is significantly inhibited by the inhibitors before the hydrolysis and the highly concentrated fermentable sugars are massively consumed by the detoxification strains
It was obviously stronger in inhibitor tolerance for A. resinae ZN1 with its fast sporulation and mycelium growth on the agar containing furfural, HMF, acetic acid, and corn stover hydrolysate, while the control strain A. resinae American Type Culture Collection (ATCC) 22711 grew slowly (Fig. 1a)

Summary

Introduction

Complete, and ultimate removal of inhibitory compounds derived from lignocellulose pretreatment is the prerequisite for efficient production of cellulosic ethanol and biochemicals. Naturally occurring microorganisms converting inhibitor compounds to less toxic derivatives had been isolated and applied in biorefinery processes [9,10,11,12,13,14,15,16,17]. The overwhelmingly conducted biodetoxification was submerged liquid culture either in pretreatment liquor (a liquid stream generated from pretreatment) or enzymatic hydrolysate (the lignocellulose slurry containing sugars, inhibitors, and lignin residue). When submerged liquid biodetoxification is conducted in pretreatment liquor, a considerable xylose is consumed by biodetoxification strains. When submerged liquid biodetoxification is conducted in enzymatic hydrolysate, the cellulase enzyme activity is significantly inhibited by the inhibitors before the hydrolysis and the highly concentrated fermentable sugars are massively consumed by the detoxification strains. To reduce the heavy sugar loss of enzymatic hydrolysates, the biodetoxification has to be conducted very quickly and high cell mass for biodetoxification is required as the whole-cell biocatalysts [17]

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Results

Discussion

Conclusion