The Acetone-Butanol-Ethanol (ABE) fermentation is receiving renewed interest as a way to upgrade renewable resources into valuable base chemicals and liquid fuels. Abundance and un-competitiveness with food sources are desired features of a potential substrate, and they are met by lignocellulosic biomass. Lignocellulosic biomass may be fermented provided that the hydrolysis in simple sugars – hexoses and pentoses - is carried out (Qureshi, Biopr Biosyst Eng, 2007, 30, 419). Although some reports on ability of Clostridium strains are available in scientific literature, no systematic investigation has been carried out. This contribution is about the characterization of the ABE fermentation by C. acetobutylicum DSM 792 using sugars representative for hydrolysis products of lignocellulosic biomass: hexoses (glucose and mannose) and pentoses (arabinose and xylose). Batch fermentations of single sugars were carried out. The conversion process was characterized as a function of time in terms of biomass, acids and solvents concentrations, pH, and total organic compounds. Effects of CaCO3 supplement to the fermentation broth were investigated. The fermentation performance of the investigated sugars decreases in the order glucose, mannose, arabinose, and xylose. The poor performance when using xylose can be explained on a metabolic level by various hypotheses: additional energy demand from H+ dependent symport of xylose into cells; inhibition or operon repression by other substrates or products (sugars/acids/solvents) (Ounine et al., Appl Environ Microbiol 1985, 49, 874); metabolic bottleneck in regeneration within the sugar conversion pathway by glyceraldehyde-3-P, which is a substrate for many other, competing reactions; metabolic bottleneck in availability of transketolase, this enzyme catalyzes two reactions. The CaCO3 supplementation improves the fermentation performance in terms of both the conversion degree of the substrate and the final solvent concentration.
Clostridium acetobutylicum Fermentation on Lignocellulosic-based Hexoses and Pentoses for Butanol Production / Raganati, Francesca; P., Götz; Olivieri, Giuseppe; Marzocchella, Antonio. - (2012). (Intervento presentato al convegno Clostridium XII - Int. Conf. on the Genetics, Physiology and Biotechnology of Solvent- and Acid-forming Clostridia tenutosi a Nottingham Conference Centre, Nottingham, UK nel 10 - 12 SEPTEMBER 2012).
Clostridium acetobutylicum Fermentation on Lignocellulosic-based Hexoses and Pentoses for Butanol Production
RAGANATI, FRANCESCA;OLIVIERI, GIUSEPPE;MARZOCCHELLA, ANTONIO
2012
Abstract
The Acetone-Butanol-Ethanol (ABE) fermentation is receiving renewed interest as a way to upgrade renewable resources into valuable base chemicals and liquid fuels. Abundance and un-competitiveness with food sources are desired features of a potential substrate, and they are met by lignocellulosic biomass. Lignocellulosic biomass may be fermented provided that the hydrolysis in simple sugars – hexoses and pentoses - is carried out (Qureshi, Biopr Biosyst Eng, 2007, 30, 419). Although some reports on ability of Clostridium strains are available in scientific literature, no systematic investigation has been carried out. This contribution is about the characterization of the ABE fermentation by C. acetobutylicum DSM 792 using sugars representative for hydrolysis products of lignocellulosic biomass: hexoses (glucose and mannose) and pentoses (arabinose and xylose). Batch fermentations of single sugars were carried out. The conversion process was characterized as a function of time in terms of biomass, acids and solvents concentrations, pH, and total organic compounds. Effects of CaCO3 supplement to the fermentation broth were investigated. The fermentation performance of the investigated sugars decreases in the order glucose, mannose, arabinose, and xylose. The poor performance when using xylose can be explained on a metabolic level by various hypotheses: additional energy demand from H+ dependent symport of xylose into cells; inhibition or operon repression by other substrates or products (sugars/acids/solvents) (Ounine et al., Appl Environ Microbiol 1985, 49, 874); metabolic bottleneck in regeneration within the sugar conversion pathway by glyceraldehyde-3-P, which is a substrate for many other, competing reactions; metabolic bottleneck in availability of transketolase, this enzyme catalyzes two reactions. The CaCO3 supplementation improves the fermentation performance in terms of both the conversion degree of the substrate and the final solvent concentration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.