Engineering bacterial sugar catabolism and tolerance toward lignocellulose conversion

Lignocellulosic biomass represents a renewable domestic feedstock that can support large-scale biochemical production processes for fuels and specialty chemicals. However, cost-effective conversion of lignocellulosic sugars into valuable chemicals still remains a challenge. Biomass recalcitrance to saccharification, microbial sugar co-utilization and toxic chemicals associated with chemical pretreatments are at the center of the bottlenecks limiting further commercialization of lignocellulose conversion. Genetic and metabolic engineering has allowed researchers to manipulate microorganisms to overcome these challenges. In this chapter, a broad overview of the current knowledge and research efforts in two paramount areas is presented: (1) bacterial carbon catabolite repression and sugar co-utilization, and (2) microbial tolerance to inhibitors derived from lignocellulose pretreatments. Lastly, technological gaps and future directions for further improvements are discussed. This chapter will mainly focus on the relevant knowledge and research progress from the perspective of bacterial strain engineering.