CHEMICAL ENGINEERING TRANSACTIONS VOL. 38, 2014 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Enrico Bardone, Marco Bravi, Taj Keshavarz Copyright © 2014, AIDIC Servizi S.r.l., I SBN 978-88-95608-29-7; I SSN 2283-9216 MFA of Clostridium Acetobutylicum Pathway: the Role of Glucose and Xylose on the Acid Formation/Uptake Francesca Raganati a , Alessandra Procentese a , Giuseppe Olivieri a,b , Maria Elena Russo c , Piero Salatino a , Antonio Marzocchella a a Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriali - Università degli Studi di Napoli Federico II, P.le V. Tecchio 80, 80125 Napoli – Italy b Bioprocess Engineering, Wageningen University, P.O. Box 8129, 6700 EV, Wageningen, the Netherlands c Istituto di Ricerche sulla Combustione, Consiglio Nazionale delle Ricerche, P.le V. Tecchio 80, 80125 Napoli - Italy giolivie@unina.it Acetone-Butanol-Etanol is typically produced during the second stage of batch fermentations of some Clostridium strains under selected operating conditions: acids are consumed along with the carbon source and pH increase This contribution reports a MFA regarding Clostridium acetobutylicum DSM 792 fermentation adopting reference sugars (glucose and xylose) as carbon sources. The attention on these sugars is particularly relevant because they are the main components of hydrolyzed lignocellulosic biomass. The results have pointed out that the butyrate formation pathway plays a fundamental role both in the accumulation of butyrate and in butyrate uptake without acetone formation. 1. Introduction The concerns regarding energy and environmental issues have revalued the interest in the use of biomass as a renewable energy source. According to this scenario, studies have bloomed in the scientific literature regarding the production of energy vectors from a wide spectrum of biomass. Solvent-producing clostridia could produce acetone, butanol, and ethanol (ABE) from several biomasses such as palm oil waste (Lee et al., 1995), agro-industrial waste(water)s (Raganati et al., 2013), and agricultural crops (Qureshi et al., 2001). The remarkable features of the butanol – e.g. hydrophobicity, high energy density, storage and transportation consistent with current structures – make this alcohol a potential substitute and/or supplement of gasoline (Table 1) (Cascone, 2008; Masiero et al., 2011). Table 1: Main features of biofuels vs. gasoline Characteristics Butanol Ethanol Gasoline Density (kg/m 3 at 20 °C) 810 789 743 Net Calorific value (Mj/kg) 32 27 43 Octane Number 86 100 87 Solubility in water (% at 25 °C ) 9 100 <0.01 ABE is produced during the fermentations of some Clostridium strains - saccharolytic butyric acid- producing bacteria - under appropriate operating conditions (C. saccharoperbutylacetonicum, C. acetobutylicum, C. beijerinckii, C. aurantibutyricum). These strains are able to metabolize a great variety of substrates, pentoses, hexoses, mono-, di- and polysaccharides (Jones and Woods, 1986). Under batch conditions, the fermentation process of solvent-producing clostridium strains proceeds with the production of cells, hydrogen, carbon dioxide, acetic acid and butyric acid during the initial growth phase (acidogenesis) (Jones and Woods 1986). As the acid concentrations increase (pH decrease), the metabolism of cells shifts to solvent production (solventogenesis) and acidogenic cells – able to reproduce themselves - shift to the solventogenesis state with a morphological change (Jones and Woods, 1986). Two different physiological states must be taken into account for Clostridia: one for the acidogenic phase, and one for the solventogenic phase. During the acidogenesis the acids production ensures high ATP and DOI: 10.3303/CET1438057 Please cite this article as: Raganati F., Procentese A., Olivieri G., Russo M.E., Salatino P., Marzocchella A., 2014, Mfa of clostridium acetobutylicum pathway: the role of glucose and xylose on the acid formation/uptake, Chemical Engineering Transactions, 38, 337-342 DOI: 10.3303/CET1438057 337