(626n) Engineering E. Coli for 2,3-Butanediol Production From Cellodextrins

2,3-Butanediol(2,3-BDO) is a bulk chemical with broad applications including as fuel and fuel additives.  A sustainable technology for synthesizing 2,3-BDO from renewable biomass  is important to alleviate the dependence on oil supply for the production of bulk chemicals and fuels. While microbial production of 2,3-BDO was shown previously with engineered E. coli from glucose, consolidated production of 2,3-BDO directly from cellulosic material offers an opportunity to bring the technology to be competitive with petroleum-based production route. 

In this presentation, we describe an effort in our laboratores toward a cellulosic 2,3-BDO. We have successfully engineered an E. coli to utilize cellodextrins, the hydrolysis intermediates from cellulose depolymerization by periplasmic expression of a cellodextrinase. The resulting strain grew well on a cellodextrins with varying degrees of polymerization. A synthetic operon for BDO biosynthesis was constructed and inserted in the cellodextrinase-expressing cells, resulting in a biocatalyst capable of converting cellodextrin to 2,3-BDO with 84% conversion yield without exogenous β-glucosidase.

To the best of our knowledge, this is the first successful engineering effort that led to cellodextrin-utilizing E. coli for 2,3-BDO production.  This is an important step toward consolidated bioprocessing for production of biofuel and biorefinery products from lignocelluloses. The ability for the biocatalyst to directly use cellodextrins eliminates the need for exogenous β-glucosidase and removes from hydrolysate cellobiose and cellodextrins, potential inhibitors for the cellulases. Further, by combining these catalysts with other strains of E. coli or other microorganisms that produces cellulases, a true-consolidated bioprocess could result, leading to a more cost-effective technology.