Production of acetone-butanol-ethanol (ABE) in a continuous flow bioreactor using degermed corn and Clostridium beijerinckii

An examination of the sustainability of the long-term cultivation of C. beijerinckii BA101 in degermed corn/saccharified degermed corn based P2 medium has been described in this work. It was found that long-term continuous cultivation of C. beijerinckii BA101 in a degermed corn based medium was not possible due to the instability of the gelatinized degermed corn starch during storage often called "retrogradation". Using this substrate, continuous ABE fermentation was run for 228 h, before the fermentation turned acidogenic. However continuous fermentations of saccharified degermed corn with normal and half P2 medium nutrients were successful. In saccharified degermed corn continuous fermentation, ABE concentration up to 14.28 g/L was achieved at a dilution rate of 0.03 h(-1). This work demonstrated that byproduct (germ/oil, corn fiber) credit can be obtained by fermenting saccharified degermed corn in continuous flow bioreactors. Additionally significant savings can be achieved by supplementing with half of normal P2 medium nutrients. (c) 2006 Elsevier Ltd. All rights reserved.