P26: Simultaneous utilization of glucose, xylose and arabinose in the presence of acetate by a consortium of Escherichia coli strains

Substrate-selective uptake is a novel approach for the simultaneous consumption of sugars found in biomass hydrolysates. Using an engineered consortium of strains derived from Escherichia coli C and a synthetic medium containing acetate, glucose, xylose and arabinose, we report on both the microbial removal of growth inhibitor acetate and the subsequent simultaneous utilization of the sugars. In a first stage, a strain unable to utilize glucose, xylose and arabinose (ALS1392, strain E. coli C ptsG manZ glk crr xylA araA) removed 3 g/L acetate within 30 hours.  In a subsequent second stage, three E. coli strains (ALS1370, ALS1371, ALS1391), which are each engineered to utilize only one sugar, together simultaneously utilized glucose, xylose and arabinose.  The effect of non-metabolizable sugars on the metabolism of the target sugar was minimal. The approach constitutes a significant improvement in any single-organism approach to utilize sugars found in lignocellulosic hydrolysate in the presence of acetate. The process will probably hold promise for the conversion of variable sugar feed streams, such as lignocellulosic hydrolysates.