Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis

Abstract

Pretreatment using ionic liquids (IL) is a promising approach for the conversion of lignocellulose to biofuels. Because IL can be inhibitory to enzymes and microorganisms involved in downstream hydrolysis and fermentation steps, discovery of IL-tolerant organisms and enzymes is critical for advancing this technology. Employing metatranscriptomics in the analysis of IL-enriched cultures facilitated tracking of dynamic changes in a complex microbial community at the level of gene transcription and doing so with genome resolution. Specific organisms were discovered that could simultaneously tolerate a moderate IL concentration and transcribe a diverse array of cellulolytic enzymes. Gene sequences of cellulolytic enzymes and efflux pumps from those same organisms were also identified, providing important resources for future research on engineering IL-tolerant organisms and enzymes.

Exceptional Solvent Tolerance inYarrowia lipolyticaIs Enhanced by Sterols

“…This incompatibility presents a significant barrier for novel microbial biocatalysis in ILs. While mechanisms of IL-toxicity have been proposed (22, 29, 31), the complete picture is unclear of how cells resist to ILs and whether these cells can adapt to achieve IL-tolerance for industrial compatibility (19, 20, 27). To illuminate the mechanisms of IL toxicity and enhanced tolerance (Fig.…”

“…To perform novel biotransformation in ILs, microbes need to be robust to tolerate high concentrations of solvents (19, 20). These solvents are inhibitory because they severely disrupt cell membranes and intracellular processes (21–23).…”

Gene Coexpression Connectivity Predicts Gene Targets Underlying High Ionic-Liquid Tolerance in Yarrowia lipolytica

“…ILs are toxic to most industrial workhorse microorganisms (e.g., Escherichia coli and Saccharomyces cerevisiae ). Cell growth is inhibited even at low IL concentrations, for example, 1 to 5% (vol/vol) [EMIM][OAc] ( 11 , 12 ). These ILs disrupt cell membranes and intracellular processes ( 13 – 15 ).…”

Gene Co-expression Connectivity Predicts Gene Targets Underlying High Ionic Liquid Tolerance in Yarrowia lipolytica

“…ILs are toxic to most industrial workhorse microorganisms (e.g., Escherichia coli, Saccharomyces cerevisiae). Cell growth is inhibited even at low IL concentrations, for example, (11,12). These ILs disrupt cell membranes and intracellular processes (13)(14)(15).…”