Sugaring-out extraction of 2,3-butanediol from fermentation broths

Sugaring-out is a novel phase separation method which was found firstly in the separation of acetonitrile. Nowadays sugaring-out extraction was tried in the recovery of metal ions, biomolecules, drugs and proteins, while its application in separation of hydrophilic primary metabolites from fermentation broths was unknown. In this work sugaring-out extraction of 2,3-butanediol was explored. The effects of sugars and solvents on phase separation and 2,3-butanediol distribution were investigated to obtain an appropriate sugaring-out extraction system. The system consisting of t-butanol/glucose/water was chosen to obtain the operation conditions according to 2,3-butanediol distribution and recovery, including glucose addition, 2,3-butanediol concentration and (NH4)(2)HPO4 concentration. The glucose-rich bottom phase was reused for fermentation of 2,3-butanediol after removing the solvent. When the fermentation broth (60.3 g/L 2,3-butanediol) was mixed with 30% (w/v) glucose, 1.8% (w/v) (NH4)(2)HPO4 and equal volume of t-butanol, 76.3% 2,3-butanediol was distributed into the top phase and 80.4% glucose into the bottom phase, and 78.0% soluble proteins and 86.8% lactic acid were separated from 2,3-butanediol. When the bottom phase was diluted to prepare fermentation medium, glucose consumption and 2,3-butanediol production were similar to those using freshly prepared normal fermentation medium. Sugaring-out extraction is a novel alternative separation for bio-based chemicals. (C) 2015 Elsevier Ltd. All rights reserved.