Developing a Thermotolerant Platform Strain for Co-Utilizing Substrates Derived from Acid Treated Lignocellulosic Biomass

Abstract

Through thermo-acid hydrolysis, lignocellulosic biomass generates low-cost feedstocks such as fermentable sugars along with toxic compounds. Despite of the cost effectiveness, few microbial hosts can efficiently utilize these crude substrates with harsh and inhibitory environments. In our research, we developed a thermophile, which has the potential to withstand harsh conditions, to maximize its robustness and metabolic capabilities. After both rational and random engineering approaches, the engineered strain showed comparable growth on the most abundant sugar in biomass to those of well-studied bacteria. Furthermore, the introduction of three heterologous pathways under a sugarinducible control system enabled the efficient utilization of the second abundant sugar in biomass. This strain also seems to have putative genes for utilizing toxic byproducts, suggesting its potential to alleviate toxicity by metabolism. Finally, the random engineering reinforced its ability to metabolize a biomass-derived organic acid as a nonsugar feedstock. All of these results suggested the potential candidate of this thermophile as a platform strain for lignocellulose-based biorefinery.