Distributive and collaborative push-and-pull in an artificial microbial consortium for improved consolidated bioprocessing

The consolidated bioprocessing (CBP) of lignocellulose by the synthetic microbial consortium of Trichoderma reesei and Saccharomyces cerevisiae is a promising way of biomanufacturing d -glucaric acid. However, the hindrance factor to its industrial application is the low efficiency. Therefore, we engineered T. reesei and S. cerevisiae to improve the CBP for d -glucaric acid production. T. reesei was engineered to produce more cellulase and release more fermentable sugars from lignocellulose, that is, pushing more sugars to S. cerevisiae. S. cerevisiae was engineered to metabolize cellobiose and siphon more sugars into d -glucaric acid biosynthetic pathway, that is, pulling more sugars to S. cerevisiae. This is the strategy of distributive and collaborative push-and-pull we developed and proposed in this work, which was proven successful in improving efficiencies of the CBPs of steam-exploded corn stover (SECS) for d -glucaric acid production and distiller's grains for single cell protein (SCP) production. The titer, yield and productivity of d -glucaric acid produced from 50 g/L SECS by the microbial consortium of T. reesei C10 and S. cerevisiae LGA-1C3S2 were 6.42 g/L, 0.128 g/g SECS, and 0.917 g/L/d, respectively. The titer, yield, and productivity of SCP produced from 80 g/L distiller's grains were 50.5 g/L, 0.631 g/g distiller's grains, and 8.417 g/L/d, respectively. These were much higher than the initial microbial consortia of T. reesei Rut-C30 and S. cerevisiae LGA-1 or INVSc1. The results confirmed the applicability and generalizability of distributive and collaborative push-and-pull, which has profound meaning for science and engineering.