Downloaded from www.microbiologyresearch.org by IP: 54.160.81.51 On: Mon, 19 Sep 2016 01:32:42 Note Alicycliphilus denitrificans gen. nov., sp. nov., a cyclohexanol-degrading, nitrate-reducing b-proteobacterium Tahar Mechichi, 1 Erko Stackebrandt 2 and Georg Fuchs 1 Correspondence Georg Fuchs georg.fuchs@biologie. uni-freiburg.de 1 Mikrobiologie, Institut fu ¨ r Biologie II, Universita ¨ t Freiburg, Scha ¨ nzlestr. 1, D-79104 Freiburg, Germany 2 DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Germany A facultatively denitrifying bacterium, strain K601 T , was isolated at 30 ˚ C from a municipal sewage plant on cyclohexanol as sole carbon source and nitrate as electron acceptor. Under aerobic conditions this strain used acetate, fumarate, lactate, pyruvate, crotonate, indole, glucose, vanillate, 4-hydroxybenzoate, m-cresol, o-cresol and p-cresol. Under denitrifying conditions the strain used cyclohexanol, cyclohexanone, 1,3-cyclohexanedione, 2-cyclohexenone, 1,3-cyclohexanediol (cis and trans), monocarboxylic acids (C 2 –C 7 ), adipate, pimelate, 5-oxocaproate, citrate, 2-oxoglutarate, succinate, malate, crotonate, lactate, pyruvate and fumarate. Cells were short rods, 0 . 6 mm wide and 1–2 mm long, motile, non-spore-forming, Gram-negative, and catalase- and oxidase-positive. Strain K601 T used nitrate, nitrite and oxygen as electron acceptors, but not sulfate, sulfite or fumarate. The DNA G+C content of strain K601 T was 66 mol%. Phylogenetic analysis, based on 16S rDNA sequencing, showed that strain K601 T represents a separate lineage of the family Comamonadaceae in the b-subclass of Proteobacteria. Based on the high 16S rDNA sequence divergence and phenotypic characteristics, the name Alicycliphilus denitrificans gen. nov., sp. nov. is proposed for this strain. The type strain is K601 T (5DSM 14773 T 5CIP 107495 T ). Alicyclic compounds, naturally made by plant cells as secondary metabolites and occurring in fossil fuels, are widespread in nature. They are also natural intermediates in the anaerobic degradation of aromatic compounds. In chemical industries they serve as insecticides, herbicides and as intermediates or solvents in many chemical reac- tions. Micro-organisms have the ability to use a variety of these xenobiotic compounds and convert them to cellular metabolites under aerobic or anoxic conditions. The aerobic degradation of alicyclic compounds has been extensively studied in several aerobic bacterial genera such as Acinetobacter (Donoghue & Trudgill, 1975), Pseudomonas (Tanaka et al., 1977) and Xanthobacter (Trower et al., 1985). The aerobic degradation of alicyclic compounds requires molecular oxygen and monooxygenases for the cleavage of the ring. Anaerobic degradation of alicyclic compounds has been less well studied and little information on this field is available (Evans, 1977; Trudgill, 1984; Dangel et al., 1988, 1989; Foss & Harder, 1998; Foss et al., 1998). Three isolates growing under denitrifying conditions with alicyc- lic compounds such as cyclohexanol have been obtained (Dangel et al., 1988) and two of them were studied (Dangel et al., 1988, 1989). Since the isolates were rather similar to each other, only one isolate, referred to as strain K601 T , has been studied in greater detail. In this paper we report the description of this strain as Alicycliphilus denitrificans gen. nov., sp. nov. Strain K601 T , previously identified as a Pseudomonas species, was isolated from a waste water treatment plant with cyclohexanol as sole carbon source and nitrate as electron acceptor (Dangel et al., 1988). The medium used for enrichment, isolation and routine cultivation con- tained (l 21 distilled water): 1 . 08 g KH 2 PO 4 ,5 . 6gK 2 HPO 4 , 0 . 54 g NH 4 Cl, 0 . 15 g CaCl 2 . 2H 2 O, 0 . 2 g MgSO 4 . 7H 2 O, 1 . 27 g NaNO 3 , 1 ml trace element solution SL-10 (Widdel et al., 1983), 1 ml selenite/tungstate solution (Tschech & Pfennig, 1984), 1 ml vitamin solution VL-7 (Pfennig, 1978) and carbon source (1 mM cyclohexanol). The final pH was 7 . 2–7 . 4. The medium was made anaerobic by applying several cycles of vacuum and flush- ing with oxygen-free nitrogen gas at room temperature. For aerobic growth, the same medium composition was used except that it did not contain NaNO 3 . Cultures were routinely grown at 30 ˚ C and aerobically grown cultures Published online ahead of print on 28 June 2002 as DOI 10.1099/ ijs.0.02276-0. The EMBL accession number for the 16S rDNA sequence of strain K601 T is AJ18042. 02276 G 2003 IUMS Printed in Great Britain 147 International Journal of Systematic and Evolutionary Microbiology (2003), 53, 147–152 DOI 10.1099/ijs.0.02276-0