A rcanobacterium

Abstract

Ar.ca.no.bac.te'ri.um. L. masc. adj. arcanus secret, hidden, secretive; N.L. neut. n. bacterium a small rod; N.L. neut. n. Arcanobacterium secretive bacterium. Actinobacteria / Actinobacteria / Actinomycetales / Actinomycetaceae / Arcanobacterium Slender, irregular, bacillary forms predominate during the first 18 h of growth; many cells are arranged at an angle to give V formations. As growth proceeds, cells become granular and segmented so that they resemble small and irregular cocci. Both rods and coccoid cells are Gram‐stain‐positive, non‐acid‐fast, and nonmotile; endospores are not formed. Facultatively anaerobic; growth is considerably enhanced in an atmosphere of increased CO 2 tension. Growth is sparse on ordinary media, but enhanced by blood or serum. The optimum temperature for growth is 37°C. Organisms will not withstand heating at 60°C for 15 min. Chemoorganotrophic, having a fermentative type of carbohydrate metabolism. Fermentation end products include acetic and lactic acids; the amount of succinic acid produced may vary from species to species and may even be difficult to detect. Catalase‐positive and ‐negative. Nitrate reduction is usually negative. Characteristic amino acids of the cell‐wall peptidoglycan of those species whose peptidoglycan has been examined in detail are based on l ‐lysine. Other chemotaxonomic properties include rhamnose and glucose as diagnostic whole‐cell sugars, lack of mycolic acids, and N ‐acetylated muramic acid residue of the peptidoglycan and MK‐9 (H 4 ) as the major respiratory quinone. DNA G + C content (mol%) : 50–57. Type species : Arcanobacterium haemolyticum Collins et al. 1982b, VL10.