Combination of Ph Adjusting and Intermittent Feeding Can Improve Fermentative Acetone-Butanol-Ethanol (Abe) Production from Steam Exploded Corn Stover

Abstract

Steam explosion (SE) is an effective and industrially scalable lignocellulose pretreatment method, which can be used for second-generation biobutanol production by acetone-butanol-ethanol (ABE) fermentation. Nevertheless, a series technical barrier such as the high inhibition of SE hydrolysate, low concentration, and low yield of ABE production hindered the availability of SE technique. In this study, aiming to solve the above obstacles and boosting cellulosic ABE production, the ABE fermentation process was intensified by a novel strategy that combine the pH adjusting with intermittent feeding. Results revealed that maintaining the pH at 6.5 for initial 12 h of cultivation ensures the smoothly shifting of the acidogenesis phase to solventogenesis phase of the C.acetobutylicum cells, so that eliminate the acid crash. While the lag period of fermentation was obvious shorted by intermittent feeding the concentrated SE hydrolysate into the diluted broth. Consequentially, 17.75 g/L of ABE (11.75 g/L of butanol) can be obtained within 48 h of fermentation, with the yield and productivity of 0.36 g/g (of sugars) and 0.37 g/L‧h, respectively. Correspondingly, 194.9 g of ABE (129.0 g of butanol) can be produced from 1 kg of dried corn stover .

Keywords: Steam explosion, pH control, Acetone-butanol-ethanol fermentation, Intermittent feeding, Biorefinery