Evaluation of solvents for extractive butanol fermentation with Clostridium acetobutylicum and the use of poly(propylene glycol) 1200

Abstract

In an effort to improve the viability of acetone-butanol-ethanol fermentation by extractive fermentation, 63 organic solvents, including alkanes, alcohols, aldehydes, acids, and esters, were experimentally evaluated for biocompatibility with Clostridium acetobutylicum by observing gas evolution from cultures in contact with candidate solvents. Thirty-one of these solvents were further tested to determine their partition coefficient for butanol in fermentation medium. The biocompatible solvent with the highest partition coefficient for butanol (4.8), was poly(propylene glycol) 1200, which was selected for fermentation experiments. This is the highest partition coefficient reported to date for a biocompatible solvent. Extractive fermentations using concentrated feeds were observed to produce up to 58.6 g. 1-1 acetone and butanol in 202 h, the equivalent of three control fermentations in a single run. Product yields (based on total solvent products and glucose consumed) of 0.234 g . g -1 to 0.311 g . g -1 and withinrun solvent productivities of 0.174 g. 1-1. h -1 to 0.290 g. 1-1. h -1 were consistent with conventional fermentations reported in the literature. The extended run-time of the fermentation resulted in an overall improvement in productivity by reducing the fraction of between-run down-time for fermentor cleaning and sterilization.

Propionic acid production by extractive fermentation. I. Solvent considerations

“…Log P is the logarithm of the K d of the solvent in a standard octanol-water two-phase system and serves as an inverse quantitative measure of the polarity of a solvent. Increased toxicity is associated with increased polarity of the organic solvent (Barton and Daugulis, 1992;Bruce and Daugulis, 1991). Onset for toxicity was reported to be in the log P range of 4-6; solvents with log P values less than 4 were most likely to be toxic to microorganisms.…”

Biobutanol from Renewable Agricultural and Lignocellulose Resources and Its Perspectives as Alternative of Liquid Fuels

“…Thirty-one of these solvents were further tested to determine their partition coefficients for butanol in fermentation medium of C. acetobutylicum. The biocompatible solvent with the highest partition coefficient for BuOH (4.8) was poly(propylene glycol) 1200 which was selected for fermentation experiments F141G [141]. Thirty-six chemicals were tested for the distribution coefficients for BuOH, the selectivity of alcohol/water separation and the toxicity towards Clostridia.…”

“…Mean productivity was estimated at 0.24 g BuOH L were consistent with conventional fermentation reported in the literature. The extended duration of fermentation resulted in an overall improvement in productivity by reducing the fraction of betweenrun down-time for fermentor cleaning and sterilization [141].…”

Production of Butyric Acid and Butanol from Biomass

“…Liquidliquid extraction, usually are membrane-assisted, has been most widely used because of its high efficiency in solvent removal and its convenience in integrating with the fermentation process . Among various extractants examined, oleyl alcohol and polypropylene glycol are the most suitable extractants (Barton and Daugulis, 1992;Davison and Thompson, 1993;Jeon and Lee, 1987;Ohno, et al, 1991). By integrating the fermentation process and liquid-liquid extraction or membrane-assisted solvent extraction, substrate consumption has been increased and higher yield and productivity for butanol were obtained (Groot, et al, 1990;Jeon and Lee, 1989).…”

“…Acetone-butanol-ethanol fermentation (ABE fermentation) with the strict anaerobic bacterium, Clostridium acetobutylicum, was once one of the largest fermentation processes ever developed in industry. However, with a few exceptions, anaerobic fermentation processes for production of fuels and chemicals, including ABE fermentation, usually suffer from a number of serious limitations including low yields, low productivity, and low final product concentrations (2)(3). It is likely that the fermentation route is now competitive with petroleum-based solvent synthesis because the limitations are now overcome (4).…”