Further study and manipulation of T. saccharolyticum CCR should enable the engineering of strains that co-utilize mixed sugars to achieve increased metabolic yield and wider feedstock utilization.
A hallmark of C. glutamicum is its ability to co-utilize various carbon sources when these are added as carbon source mixtures.
Microorganisms that can co-utilize glucose and xylose are of considerable interest to the biofuels industry due to their ability to simplify the fermentation processes.
Overall, this study elucidates the biological pathway to co-utilize levoglucosan and cellobiosan, which will be a key transformation for the biological upgrading of pyrolysis-derived substrates.
In this study, we designed an in vitro 15-enzyme pathway that can co-utilize sucrose, glucose, and fructose in the anodic compartment of EFCs.
However, and contrary to C. thermocellum (Weimer and Zeikus 1977), cultures grown on glucose/cellobiose mixtures demonstrated that C. acetobutylicum was unable to co-utilize both substrates at the same time and glucose was consistently the preferred carbon source.
Escherichia coli W3110 was previously engineered to co-utilize glucose and xylose by replacing the wild-type crp gene with a crp* mutant encoding a cAMP-independent CRP variant (Cirino et al., 2006 [Cirino, P.C., Chin, J.W., Ingram, L.O., 2006. Engineering Escherichia coli for xylitol production from glucose xylose mixtures. Biotechnol. Bioeng. 95, 1167 1176.]).
Moreover, both hexuronates were co-utilized with glucose by the recombinant C. glutamicum strains developed here.
The engineered yeast strain efficiently co-utilized glucose and xylose for fermentation, elevating ethanol yields.
When present in mixtures with glucose, the recombinant C. glutamicum strains co-utilized D-galacturonate with glucose and D-glucuronate with glucose, respectively.
The engineered strain also co-utilized cellobiose with mannose or galactose; however, it was unable to metabolize cellobiose in the presence of arabinose and glucose.
