International Journal of Systematic and Evolutionary Microbiology (2001), 51, 2049–2054 Printed in Great Britain Isolation of a cinnamic acid-metabolizing Clostridium glycolicum strain from oil mill wastewaters and emendation of the species description 1 Laboratoire de Microbiologie IRD, IFR-BAIM, Universite  s de Provence et de la Me  diterrane  e, ESIL case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 9, France 2 Microbial Research and Discovery Unit, School of Biomolecular and Biomedical Sciences, Faculty of Science, Griffith University, Brisbane, Queensland 4111, Australia Mohamed Chamkha, 1 Marc Labat, 1 Bharat K. C. Patel 2 and Jean-Louis Garcia 1 Author for correspondence : Jean-Louis Garcia. Tel : 33 4 9182 8572. Fax: 33 4 9182 8570. e-mail : garciaesil.univ-mrs.fr A strictly anaerobic, Gram-positive, motile, sporulated bacterium, designated strain CIN5, was isolated from olive mill wastewaters after enrichment on cinnamic acid. The rod-shaped cells were slightly curved (04–1120–15 μm) and occurred singly or in pairs. Strain CIN5 utilized a limited number of carbohydrates (glucose, fructose, maltose, sorbitol), grew optimally at 37 SC and at pH 73–75 and had a DNA GMC content of 291O03 mol%. Strain CIN5 was very closely related to Clostridium glycolicum DSM 1288 T . Both strain CIN5 and the type strain of C. glycolicum transformed cinnamic acid to hydrocinnamic acid and a wide range of other cinnamic acid derivatives, including o-, m- and p-coumaric, o-, m- and p-methoxycinnamic, p- methylcinnamic, caffeic, ferulic and isoferulic acids, to their corresponding 3- phenylpropionic acids by reducing the double bond of the side chain. Glucose supplementation increased the rate of conversion markedly. The emendation of the description of C. glycolicum is proposed to include these new characteristics. Keywords : Clostridium glycolicum, aromatic compounds, metabolism, emendation, oil mill wastewater INTRODUCTION Olive mill wastewater (OMW) is a major environ- mental problem in the Mediterranean region, where more than 30 million m of this residue are produced annually. The press processing of 1 ton of olives produces 05–08m of OMW (Boari et al., 1984). The OMW has a dark brown colour, an unpleasant odour and a variable and heterogeneous chemical compo- sition that depends on the olive species, the stage of ripening, the oil-extraction process and the climatic conditions. Chemically, OMW contains sugars, tannins, polyphenols, polyalcohols, pectins, lipids and a wide variety of simple aromatic compounds resulting from olive cell-wall degradation during the oil-ex- traction process. The main simple phenolic compounds in OMW include tyrosol, hydroxytyrosol and syringic, ................................................................................................................................................. Abbreviation : OMW, olive mill wastewater. The GenBank accession number for the 16S rRNA gene sequence of strain CIN5 is AY007244. p-hydroxyphenylacetic, vanillic, veratric, proto- catechuic, caffeic, p-coumaric and cinnamic acids (Balice & Cera, 1984 ; Hamdi, 1993 ; Labat et al., 2000). The maximum BOD (biological oxygen demand) and COD (chemical oxygen demand) reach 100 and 220 kg m -, respectively (Balice et al., 1982). The polyphenols of OMW can inhibit the growth of some bacteria and Hep2 human cells (Capasso et al., 1995). Catabolism of the main cinnamic compounds derived from the degradation of lignin and other aromatic constituents of plants ( p-coumaric, caffeic, ferulic and cinnamic acids) is an important step of the carbon cycle by which natural aromatics and many industrial pollutants are degraded (Andreoni & Bestetti, 1986). The final fate of these compounds is to reach the soil (Subba Rao et al., 1971). Strains of bacteria, yeast and fungi have been shown to metabolize hydroxycinnamic acids and to be resistant to the inhibitory effects of these compounds (Edlin et al., 1994). Most often, free cinnamic acid derivatives are metabolized by different micro-organisms into 4-vinyl derivatives and then 01818  2001 IUMS 2049