A two-step bioprocessing strategy in pentonic acids production from lignocellulosic pre-hydrolysate.

Efficient utilization (over needless disposal) of biorefinery pre-hydrolysate is an economically relevant practice for improving biorefinery financial prospects. The liquid fraction obtained after acid hydrolysis pretreatment of lignocellulosic biomass, called pre-hydrolysate, are predominantly comprised of hemicellulosic carbohydrates. Using a two-step bioprocess, the hexoses were selectively fermented to ethanol by S. cerevisiae to clear the path for Gluconobacter oxydans transformation of pentoses to a high purity pentonic acids solution. Finally, approximately 180 g pentonic acids and 19 g ethanol could be produced starting from pre-hydrolysate produced from 1 kg corn stover. The results demonstrate execution of our objective to prove this bioconversion method for producing high purity pentonic acids starting from crude lignocellulosic pre-hydrolysate, a wastefully disregarded biorefinery process stream.