Downloaded from www.microbiologyresearch.org by IP: 54.70.40.11 On: Wed, 02 Jan 2019 20:20:24 Corynebacterium atypicum sp. nov., from a human clinical source, does not contain corynomycolic acids Val Hall, 1 Matthew D. Collins, 2 Roger A. Hutson, 2 Paul A. Lawson, 2 Enevold Falsen 3 and Brian I. Duerden 1 Correspondence Val Hall hallv@cardiff.ac.uk 1 Anaerobe Reference Unit, PHLS, University Hospital of Wales, Cardiff CF14 4XW, UK 2 School of Food Biosciences, University of Reading, Reading, UK 3 Culture Collection, Department of Clinical Bacteriology, University of Go ¨ teborg, Go ¨ teborg, Sweden An unusual Gram-positive, facultatively anaerobic, catalase-positive, diphtheroid-shaped organism originating from an unknown human clinical source was characterized by biochemical, molecular chemical and molecular phylogenetic methods. Based on its morphological and biochemical characteristics and the presence of a murein based on meso-diaminopimelic acid, the unidentified organism was tentatively assigned to the genus Corynebacterium. However, the unknown organism was found to lack the distinctive, short-chain corynomycolic acids that are considered to be characteristic of this genus. Despite the absence of these characteristic lipids, comparative 16S rRNA gene sequencing showed that the unknown bacterium was phylogenetically a member of the genus Corynebacterium and was distinct from all currently known species. Based on both phenotypic and 16S rRNA sequence considerations, it is proposed that the unknown organism be classified as a novel species, Corynebacterium atypicum sp. nov. The type strain of C. atypicum is strain R2070 T (=CCUG 45804 T =CIP 107431 T ). Amongst the coryneform group of bacteria, the genus Corynebacterium comprises the largest number of species. The genus currently contains over 50 species, a high proportion of which have been defined during the past decade. Most of the newly described species have originated from clinical specimens, where they occur as cutaneous or mucocutaneous contaminants, and have come to light as a result of increased interest in the possible role of such organisms as opportunistic pathogens and due to the implementation of improved molecular diagnostic method- ologies (Funke et al., 1997). Despite the rapid expansion in the number of corynebacterial species, there is strong evidence that much species diversity remains to be defined, especially from human sources (Tanner et al., 1999). The genus Corynebacterium forms a monophyletic grouping (Pascual et al., 1995), and species of this genus, with few exceptions (Corynebacterium amycolatum Collins et al. 1988 and Corynebacterium kroppenstedtii Collins et al. 1998), are characterized by the presence of distinctive low-molecular- mass a-alkyl-b-hydroxy long-chain fatty acids (designated corynomycolic acids) (Collins & Cummins, 1986). In the course of an on-going study of taxonomically problematic coryneforms from human sources, we have characterized a hitherto-unknown corynebacterium-like organism that lacks corynomycolic acids. Based on both phenotypic and phylogenetic evidence, we propose yet another novel species of the genus Corynebacterium, Corynebacterium atypicum sp. nov. Strain R2070 T was submitted to the Anaerobe Reference Unit, PHLS, University Hospital of Wales, Cardiff, UK, for identification and originated from an unknown human clinical source. The unidentified rod-shaped isolate was cultured on Columbia agar (Difco) supplemented with 5 % horse blood at 37 uC, in air plus 5 % CO 2 . The strain was characterized biochemically by using the API Coryne and API ZYM systems according to the manufacturer’s instruc- tions (API bioMe ´rieux). Cell-wall murein was prepared by mechanical disruption of cells and complete acid hydro- lysates were analysed as described by Schleifer & Kandler (1972). Fatty acid methyl esters were prepared and analysed as described by Ka ¨mpfer & Kroppenstedt (1996) and the presence of mycolic acids was investigated by GLC analy- sis of trimethylsilylated derivatives (TMS-MAME) (Klatte et al., 1994). The 16S rRNA gene of the isolate was ampli- fied by PCR and sequenced directly using a Taq dye-deoxy terminator cycle sequencing kit (Applied Biosystems) and an automatic DNA sequencer (model 373A; Applied Biosystems). The closest known relatives of the novel isolate The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain CCUG 45804 T is AJ441057. 02442 G 2003 IUMS Printed in Great Britain 1065 International Journal of Systematic and Evolutionary Microbiology (2003), 53, 1065–1068 DOI 10.1099/ijs.0.02442-0