Simultaneous production of bioethanol and biohydrogen by Escherichia coli WDHL using wheat straw hydrolysate as substrate

•Genetically modified E. coli WDHL strain produces simultaneously both ethanol and hydrogen from pentoses.•Mesophilic E. coli WDHL has similar ethanol yield than thermophile microorganisms.•This is the first report using wheat straw hydrolysate as substrate to produce two biofuels in one step by E. coli.

This study reports the ability of Escherichia coli WDHL to metabolize pentoses commonly found in lignocellulosic hydrolysates to produce bioethanol (EtOH) and biohydrogen (H2). A Central Composite experimental design was used to establish the effects of pH, temperature and total reducing sugars (TRS) from the wheat straw hydrolysate (WSH) on production, production rate and yield of bioethanol and biohydrogen. Optimal conditions for the simultaneous production were pH 8.2, 31 °C and 23.4 g TRS dm−3. Batch culture was performed with these conditions in a 1 dm3 bioreactors, obtaining: 8.9 g EtOH dm−3, 0.050 g EtOH dm−3 h−1, 0.38 g EtOH g TRS−1, and 3277.7 cm3 H2, 18 cm3 H2 dm−3 h−1, 140.1 cm3 H2 g TRS−1. The results showed that the pH and the temperature affected the production of both biofuels. This work enriches the information of simultaneous production of bioethanol and biohydrogen by using second-generation substrates.

Graphical abstractDownload high-res image (187KB)Download full-size image