Consolidated bioprocessing of lignocellulose for production of glucaric acid by an artificial microbial consortium

Abstract

The biomanufacturing of D-glucaric acid has been attracted increasing interest and the industrial yeast Saccharomyces cerevisiae is regarded as an excellent host for D-glucaric acid production. Here we constructed the biosynthetic pathway of D-glucaric acid in S. cerevisiae INVSc1 whose opi1 was knocked out and obtained two engineered strains, LGA-1 and LGA-C, producing record breaking titers of D-glucaric acid, 9.53 {+/-} 0.46 g/L and 11.21 {+/-} 0.63 g/L D-glucaric acid from 30 g/L glucose and 10.8 g/L myo-inositol in the mode of fed-batch fermentation, respectively. Due to the genetic stability and the outperformance in subsequent applications, however, LGA-1 was a preferable strain. As one of the top chemicals from biomass, there have been no reports on D-glucaric acid production from lignocellulose, which is the most abundant renewable on earth. Therefore, the biorefinery processes of lignocellulose for D-glucaric acid production including separated hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and consolidated bioprocessing (CBP) were investigated in this work and CBP by an artificial microbial consortium composed of Trichoderma reesei Rut-C30 and S. cerevisiae LGA-1 was found to have relatively high D-glucaric acid titers and yields after 7 d fermentation, 0.54 {+/-} 0.12 g/L D-glucaric acid from 15 g/L Avicel, and 0.45 {+/-} 0.06 g/L D-glucaric acid from 15 g/L steam exploded corn stover (SECS), respectively. In attempts to design the microbial consortium for more efficient CBP the team consisted of the two members, T. reesei Rut-C30 and S. cerevisiae LGA-1, was found to be the best with excellent work distribution and collaboration. This desirable and promising approach for direction production of D-glucaric acid from lignocellulose deserves extensive and in-depth research.