INTERNATIONALJOURNAL OF SYSTEMATICBACTERIOLOGY, July 1987, p. 287-288 Vol. 31, No. 3 0020-7713187103287-02$02.OO/O Copyright 0 1987, International Union of Microbiological Societies

Transfer of Arthrobacter variabilis (Muller) to the Genus Corynebacterium, as Corynebacterium variabilis comb. nov. MATTHEW DAVID COLLINS Department of Food Microbiology, AFRC Institute of Food Research, Shinfield, Reading RG2 9AT, England

Arthrobacter variabilis (Miiller) differs so much from the type species of the genus Arthrobacter, Arthrobacter globiforrnis, that it should not be retained within this genus. On the basis of biochemical and chemical criteria, it is proposed that Arthrobacter variubilis be reclassified in the genus Corynebacterium, as Corynebacterium vuriubilis comb. nov. The type strain is ATCC 15753 (NCIB 9455).

The species Arthrobacter variabilis was originally isolated positive, oxidase negative. Murein is of the directly cross- from animal fodder and assigned to the genus Arthrobacter linked type based on rneso-diaminopimelic acid. The glycan by Miiller in 1961 (7). The placement of this species in the moiety of murein contains only acetyl residues. The cell wall genus Arthrobacter has always been controversial, and contains an arabinogalactan polymer. Short-chain mycolic recent chemotaxonomic studies clearly indicate that this acids (30 to 36 carbon atoms) are present. Long-chain fatty microorganism should be reclassified in the genus Coryne- acids are of the straight-chain saturated, mono-unsaturated, bacterium (1, 2, 6, 8, 10). It is now universally accepted that and 10-methyl-branched types. The major menaquinones are the genus Arthrobacter should be restricted to those species MK-9(H2) and MK-8(H2). The deoxyribonucleic acid base which possess a murein based on L-lysine (5). A. variabilis composition is 65 mol% guanine plus cytosine (T,). The type differs from true arthrobacters in possessing a directly cross- strain is ATCC 15753 (NCIB 9455). The characteristics of linked murein based on meso-diaminopimelic acid (6, 8), a the type strain correspond to those of the species. type consistent, however, with the genus Corynebacterium Other distinguishing characteristics. Corynebacterium (1). The wall of A. variabilis also differs from that of true variabilis can be readily distinguished from other arthrobacters but is similar to that of Corynebacterium spp. Corynebacterium species in containing high levels of 10- in containing an arabinogalactan polymer (6). Support for the methyloctadecanoic (tuberculostearic) acid. The only other inclusion of A. variabilis in the genus Corynebacterium also authentic Corynebacterium species known to contain this comes from the reports of short-chain mycolic acids (30 to 36 acid is C. minutissirnum. C. variabilis, however, can be carbon atoms) and predominantly straight-chain saturated, readily distinguished from the latter species in being aerobic mono-unsaturated, and 10-methyl-branched long-chain fatty and in possessing a substantially higher guanine-plus- acids in this species (1, 2). True members of the genus cytosine content (ca. 56 to 59 mol% for C. minutissimum) Arthrobacter lack mycolic acids and contain predominantly (1). straight-chain saturated, iso- and anteiso-methyl-branched long-chain fatty acids (4). A. variabilis also differs from true arthrobacters in possessing phosphatidylinositol diaman- LITERATURE CITED nosides (Collins, unpublished data). A. variabilis has also 1, Collins, M. D., and C. S. Cummins. 1986. Genus Corynebac- been shown to be unrelated to true arthrobacters on the basis terium Lehmann and Wuemann, p. 1266-1276. In P. H. A. of 16s ribosomal RNA cataloging (10). These studies have Sneath (ed.), Bergey’s manual of systematic bacteriology, vol. demonstrated that A. variabilis is more closely related to 2. The Williams and Wilkins Co., Baltimore. true corynebacteria than to the other mycolic acid- 2. Collins, M. D., M. Goodfellow, and D. E. Minnikin. 1982. A containing genera Mycobacterium, Nocardia, and survey of the structure of mycolic acids in Corynebacteriurn and Rhodococcus (10). Therefore, in view of the overwhelming related taxa. J. Gen. Microbiol. 128:129-149. phenotypic and phylogenetic evidence, it is formally pro- 3. Collins, M. D., M. Goodfellow, and D. E. Mhnikin. 1982. Fatty posed that A. variabilis be removed from the genus acid composition of some mycolic acid-containing coryneform Arthrobacter Corynebacterium, bacteria. J. Gen. Microbiol. 128:2503-2509. and reclassified in the genus 4. Collins, M. D., and R. M. Kroppenstedt. 1983. Lipid composi- as Corynebacterium variabilis comb. nov. tion as a guide to the classification of some coryneform bacteria Description of Corynebacteriurnvariabilis comb. nov. Gram- containing an A4a type peptidoglycan (Schleifer and Kandler). positive, strictly aerobic, nonmotile, rod-shaped cells (0.8 to Syst. Appl. Microbiol. 4:95-104. 1.1 by 1.4 to 3.5 pm). Cells are irregular (club-shaped or 5. Keddie, R. M., M. D. Collins, and D. Jones. 1986. Genus tapered) and occur singly, in pairs with typical V forms or Arthrobacter Conn and Dimmick, p. 1288-1301. In P. H. A. clumps; ovoid forms occur in older cultures. Colonies are Sneath (ed.), Bergey’s manual of systematic bacteriology, vol. small (ca. 2 to 4 mm), circular (sometimes irregular), convex, 2. The Williams and Wilkins Co., Baltimore. and grey-white (occasionally slight pink) with a dry appear- 6. Keddie, R. M., and G. L. Cure. 1977, The cell wall composition and distribution of free mycolic acids in named strains of ance. Optimum temperature is between 25 and 30°C. Grows coryneform bacteria and in isolates from various natural in 7% NaCl. Acetate, propionate, capronate, 4-aminobuty- sources. J. Appl. Bacteriol. 42:229-253. rate, caprylate, succinate, DL-malate, levulinate, and some 7. Miiller, G. 1961. Mikrobiologische Untersuchungen iiber die other compounds may be used as sole carbon sources (9). “Futterverpilzung durch Selbsterhitzung.” 111. Mitteilung: Xanthine, tyrosine, and starch are not hydrolyzed. Catalase Ausfuhrliche Beshreibung neuer Baktenen-species. Zentralbl.

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Bakteriol. Parasitenkd. Infektionskr. Hyg. Abt. 2 Orig. Reihe A derived from numerical taxonomic studies. J. Gen. Microbial. 114:52&537. 129: 1433-1471. 8. Schleifer, K. H., and 0. Kandler. 1972. Peptidoglycan types of 10. Stackebrandt, E., B. J. Lewis, and C. R. Wokse. 1980. The bacterial cell walls and their taxonomic implications. Bacteriol. phylogenetic structure of the coryneform group of bacteria. Rev. 35407477. Zentralbl. Bakteriol. Mikrobiol. Hyg. Abt. 2 Orig. Reihe C 9. Seiler, H. 1983. Identification key for coryneform bacteria 1: 137-149.