Utilization of mechanocatalytic oligosaccharides by ethanologenic Escherichia coli as a model microbial cell factory

Mechanocatalysis is a promising method for depolymerization of lignocellulosic biomass. Microbial utilization of the resulting oligosaccharides is one potential route of adding value to the depolymerized biomass. However, it is unclear how readily these oligosaccharides are utilized by standard cell factories. Here, we investigate utilization of cellulose subjected to mechanocatalytic depolymerization, using ethanologenic Escherichia coli as a model fermentation organism. The mechanocatalytic oligosaccharides supported ethanol titers similar to those observed when glucose was provided at comparable concentrations. Tracking of the various oligomers, using maltose (alpha-1,4) and cellobiose (beta-1,4) oligomers as representative standards of the orientation, but not linkage, of the glycosidic bond, suggests that the malto-like-oligomers are more readily utilized than cello-like-oligomers, consistent with poor growth with cellotetraose or cellopentaose as sole carbon source. Thus, mechanocatalytic oligosaccharides are a promising substrate for cell factories, and microbial utilization of these sugars could possibly be improved by addressing utilization of cello-like oligomers.