ABE fermentation from enzymatic hydrolysate of NaOH-pretreated corncobs

Acetone butanol ethanol (ABE) was produced from enzymatic-hydrolyzed corncobs by Clostridium saccharobutylicum DSM 13864. Pretreatment of corncobs was carried out with 0.5 mol L−1 NaOH followed by enzymatic hydrolysis. The yield of total reducing sugars was 917 g kg−1 pretreated (de-lignified) and washed corncobs. The hydrolysate was used without sediments removal for ABE fermentation. A solvent production of 19.44 g L−1 with 12.27 g L−1 butanol was obtained from 55.22 g L−1 sugars, resulting in an ABE yield of 350 g kg−1 and a production rate of 0.54 g L−1 h−1. A control experiment using 55.3 g L−1 mixed sugars resulted in an ABE production of 16.81 g L−1 with 10.26 g L−1 butanol, corresponding to an ABE yield of 300 g kg−1 and a production rate of 0.47 g L−1 h−1, indicating that the enzymatic hydrolysates may contain stimulating compounds that can improve the ABE fermentation. •Corncobs (waste) pretreated with NaOH showed increased enzymatic digestibility.•Washing can enhance the enzymatic hydrolysis of NaOH-pretreated corncobs.•Glucose and xylose can be converted simultaneously by Clostridium saccharobutylicum.•Overall solvent yield was 210 g solvent per kg dry matter (corncobs).