Optimization of 2,3‐butanediol production by Klebsiella oxytoca through oxygen transfer rate control

Abstract

Production of 2,3-butanediol by Klebsiella oxytoca is influenced by the degree of oxygen limitation. During batch culture studies, two phases of growth are observed: energy-coupled growth, during which cell growth and oxygen supply are coupled; and, energy-uncoupled growth, which arises when the degree of oxygen limitation reaches a critical value. Optimal 2,3-butanediol productivity occurs during the energy-coupled growth phase. In this article, a control system which maintains the batch culture at a constant level of oxygen limitation in the energy-coupled growth regime has been designed. Control, which involves feedback control on the oxygen transfer coefficient, is achieved by continually increasing the partial pressure of oxygen in the feed gas, which in turn continually increases the oxygen transfer rate. Control has resulted in a balanced state of growth, a repression of ethanol formation, and an increase in 2,3-butanediol productivity of 18%.

Injection of air into the headspace improves fermentation of phosphoric acid pretreated sugarcane bagasse by Escherichia coli MM170

“…However, mixed results have been reported for air sparging during other yeast fermentations (Alfenore et al, 2004;Ghaly and El-Taweel, 1995;Schirmer-Michel et al, 2009;Zhang et al, 2010). A series of publications from G. T. Tsao's lab at Purdue University identified the optimum level of oxygen for 2,3-butanediol production by Klebsiella oxytoca (Beronio and Tsao, 1993;Jansen et al, 1984). Lawford and Rousseau (1994) tested different aeration rates during ethanol fermentation with recombinant E. coli and reported that subsurface sparging decreased ethanol yield, increased cell yield, and increased alternative fermentation products.…”

“…This in turn would lead to increased growth and ethanol production. Microaeration would also allow limited respiration and additional opportunities for NADPH production in the absence of inhibitors, both of which may serve to stimulate growth (Beronio and Tsao, 1993;Jansen et al, 1984;Lawford and Rousseau, 1994;Okuda et al, 2007). However, high levels of air typically decrease product formation.…”

Enhanced production of acetoin and butanediol in recombinant Enterobacter aerogenes carrying Vitreoscilla hemoglobin gene

“…Although the VHb-associated increases in the levels of acetoin and butanediol that we measured are fairly substantial on a relative scale, their levels are below those produced by species such as Klebsiella oxytoca [34,36] or B. polymyxa [35]. If VHb can be as effective in these latter species as in E. aerogenes, however, its use may prove to be a useful strategy for large-scale production of these solvents.…”

“…At 96 h incubation however, where no viable cells for non-vgb strains and substantially reduced number of viable cells for Ea(pUC8:15) were observed, no ALS activity was determined in any strain. Aeration rate has been found to be of great importance in the optimization of BD and acetoin production during fermentations [22,[33][34][35][36][37][38]. In general, it has been found that an aeration/oxygen supply rate that is neither too high nor too low leads to this optimization.…”

“…Acetoin and BD are the main fermentation products of E. aerogenes grown under appropriate conditions [34]. Starting with two molecules of pyruvate, BD is produced in three enzymatic steps.…”