The genus Corynebacterium was created by Lehmann and Neumann in 1896 as a taxonomic group to contain the bacterial rods responsible for causing diphtheria. The genus was defined based on morphological characteristics. Based on studies of 16S rRNA, they have been grouped into the subdivision of Gram-positive Eubacteria with high G:C content, with close phylogenetic relationships to Arthrobacter, Mycobacterium, Nocardia, and Streptomyces.[8]
The term comes from Greek κορύνη, korýnē 'club, mace, staff, knobby plant bud or shoot'[9] and βακτήριον, baktḗrion 'little rod'.[10] The term "diphtheroids" is used to represent corynebacteria that are nonpathogenic; for example, C. diphtheriae would be excluded.[citation needed] The term diphtheroid comes from Greek διφθέρα, diphthérā 'prepared hide, leather'.[11][12]
Genomics
Comparative analysis of corynebacterial genomes has led to the identification of several conserved signature indels (CSIs) that are unique to the genus. Two examples of CSIs are a two-amino-acid insertion in a conserved region of the enzyme phosphoribose diphosphate:decaprenyl-phosphate phosphoribosyltransferase and a three-amino-acid insertion in acetate kinase, both of which are found only in Corynebacterium species. Both of these indels serve as molecular markers for species of the genus Corynebacterium. Additionally, 16 conserved signature proteins, which are uniquely found in Corynebacterium species, have been identified. Three of these have homologs found in the genus Dietzia, which is believed to be the closest related genus to Corynebacterium. In phylogenetic trees based on concatenated protein sequences or 16S rRNA, the genus Corynebacterium forms a distinct clade, within which is a distinct subclade, cluster I. The cluster is made up of the species C. diphtheriae, C. pseudotuberculosis, C. ulcerans, C. aurimucosum, C. glutamicum, and C. efficiens. This cluster is distinguished by several conserved signature indels, such as a two-amino-acid insertion in LepA and a seven- or eight-amino-acid insertions in RpoC. Also, 21 conserved signature proteins are found only in members of cluster I. Another cluster has been proposed, consisting of C. jeikeium and C. urealyticum, which is supported by the presence of 19 distinct conserved signature proteins which are unique to these two species.[13] Corynebacteria have a high G+C content ranging from 46-74 mol%.[14]
Characteristics
The principal features of the genus Corynebacterium were described by Collins and Cummins, for Coryn Taylor in 1986.[15] They are gram-positive, catalase-positive, non-spore-forming, non-motile, rod-shaped bacteria that are straight or slightly curved.[16]Metachromatic granules are usually present representing stored phosphate regions. Their size falls between 2 and 6 μm in length and 0.5 μm in diameter. The bacteria group together in a characteristic way, which has been described as the form of a "V", "palisades", or "Chinese characters". They may also appear elliptical. They are aerobic or facultatively anaerobic, chemoorganotrophs. They are pleomorphic through their lifecycles, they occur in various lengths, and they frequently have thickenings at either end, depending on the surrounding conditions.[17]
Corynebacteria grow slowly, even on enriched media. In nutritional requirements, all need biotin to grow. Some strains also need thiamine and PABA.[15] Some of the Corynebacterium species with sequenced genomes have between 2.5 and 3.0 million base pairs. The bacteria grow in Loeffler's medium, blood agar, and trypticase soy agar (TSA). They form small, grayish colonies with a granular appearance, mostly translucent, but with opaque centers, convex, with continuous borders.[16] The color tends to be yellowish-white in Loeffler's medium. In TSA, they can form grey colonies with black centers and dentated borders that either resemble flowers (C. gravis), continuous borders (C. mitis), or a mix between the two forms (C. intermedium).[citation needed]
L-Lysine production is specific to C. glutamicum in which core metabolic enzymes are manipulated through genetic engineering to drive metabolic flux towards the production of NADPH from the pentose phosphate pathway, and L-4-aspartyl phosphate, the commitment step to the synthesis of L-lysine, lysC, dapA, dapC, and dapF. These enzymes are up-regulated in industry through genetic engineering to ensure adequate amounts of lysine precursors are produced to increase metabolic flux. Unwanted side reactions such as threonine and asparagine production can occur if a buildup of intermediates occurs, so scientists have developed mutant strains of C. glutamicum through PCR engineering and chemical knockouts to ensure production of side-reaction enzymes are limited. Many genetic manipulations conducted in industry are by traditional cross-over methods or inhibition of transcriptional activators.[47]
Expression of functionally active human epidermal growth factor has been brought about in C. glutamicum,[48] thus demonstrating a potential for industrial-scale production of human proteins. Expressed proteins can be targeted for secretion through either the general secretory pathway or the twin-arginine translocation pathway.[49]
^Lehmann KB, Neumann R (1896). Atlas und Grundriss der Bakteriologie und Lehrbuch der speziellen bakteriologischen Diagnostik [Atlas and outline of bacteriology and textbook of special bacteriological diagnostics] (1st ed.). München: J.F. Lehmann.
^Lehmann KB, Neumann R (1907). Lehmann's Medizin, Handatlanten X. Atlas und Grundriss der Bakteriologie und Lehrbuch der speziellen bakteriologischen Diagnostik [Lehmann's Medicine, Handbook X. Atlas and outline of bacteriology and textbook of special bacteriological diagnostics] (4th ed.). Munchen: J. F. Lehmann.
^Bernard, K.A.; Funke, G. (2012). "Genus I. Corynebacterium". In Goodfellow, M.; Kampfer, P.; Busse, H.J.; Trujillo, M.E.; Suzuki, K.; Ludwig, W.; Whitman, W.B. (eds.). Bergey's Manual of Systematic Bacteriology (2nd ed.). Springer. p. 245.
^ abCollins, M. D.; Cummins, C. S. (1986). "Genus Corynebacterium Lehmann and Neumann 1896, 350AL". In Sneath, P. H. A.; Mair, N. S.; Sharpe, M. E.; Holt, J. G. (eds.). Bergey's Manual of Systematic Bacteriology. Vol. 2. Baltimore: Williams & Wilkins. pp. 1266–76.
^Keddie, R. M.; Cure, G. L. (1977). "The Cell Wall Composition and Distribution of Free Mycolic Acids in Named Strains of Coryneform Bacteria and in Isolates from Various Natural Sources". Journal of Applied Bacteriology. 42 (2): 229–52. doi:10.1111/j.1365-2672.1977.tb00689.x. PMID406255.
^Oteo, Jesús; Aracil, Belén; Ignacio Alós, Juan; Luis Gómez-Garcés, Jose (2001). "Bacteriemias significativas por Corynebacterium amycolatum: Un patógeno emergente" [Significant bacteremias by Corynebacterium amycolatum: an emergent pathogen]. Enfermedades Infecciosas y Microbiología Clínica (in Spanish). 19 (3): 103–6. doi:10.1016/S0213-005X(01)72578-5. PMID11333587. S2CID72540272.
^Lagrou, K; Verhaegen, J; Janssens, M; Wauters, G; Verbist, L (1998). "Prospective Study of Catalase-positive Coryneform Organisms in Clinical Specimens: Identification, Clinical Relevance, and Antibiotic Susceptibility". Diagnostic Microbiology and Infectious Disease. 30 (1): 7–15. doi:10.1016/S0732-8893(97)00193-4. PMID9488824.
^Boc, SF; Martone, JD (1995). "Osteomyelitis caused by Corynebacterium jeikeium". Journal of the American Podiatric Medical Association. 85 (6): 338–9. doi:10.7547/87507315-85-6-338. PMID7602508.
^León, Cristóbal; Ariza, Javier (2004). "Guías para el tratamiento de las infecciones relacionadas con catéteres intravasculares de corta permanencia en adultos: Conferencia de consenso SEIMC-SEMICYUC" [Guidelines for the treatment of infections related to short-stay intravascular catheters in adults: consensus conference SEIMC-SEMICYUC]. Enfermedades Infecciosas y Microbiología Clínica (in Spanish). 22 (2): 92–7. doi:10.1016/S0213-005X(04)73041-4. PMID14756991.
^Natsch, A.; Gfeller, H.; Gygax, P.; Schmid, J. (2005). "Isolation of a bacterial enzyme releasing axillary malodor and its use as a screening target for novel deodorant formulations1". International Journal of Cosmetic Science. 27 (2): 115–22. doi:10.1111/j.1467-2494.2004.00255.x. PMID18492161. S2CID22554216.
^Yamada, K.; Kinoshita, S.; Tsunoda, T.; Aida, K., eds. (1972). The Microbial Production of Amino Acids. New York: Wiley.
^Constantinides, Alkis (1980). "Steroid transformation at high substrate concentrations using immobilized Corynebacterium simplex cells". Biotechnology and Bioengineering. 22 (1): 119–36. doi:10.1002/bit.260220110. PMID7350926. S2CID29703826.
^Milas, Luka; Scott, Martin T. (1978). "Antitumor Activity of Corynebacterium Parvum". In Ford, Marvella E.; Watson, Dennis K. (eds.). Cancer Disparities. Advances in Cancer Research. Vol. 26 (1st ed.). pp. 257–306. doi:10.1016/S0065-230X(08)60090-1. ISBN978-0-12-809878-3. PMID343523.
^Meissner, Daniel; Vollstedt, Angela; Van Dijl, Jan Maarten; Freudl, Roland (2007). "Comparative analysis of twin-arginine (Tat)-dependent protein secretion of a heterologous model protein (GFP) in three different Gram-positive bacteria". Applied Microbiology and Biotechnology. 76 (3): 633–42. doi:10.1007/s00253-007-0934-8. PMID17453196. S2CID6238466.
Hansmeier, N.; Chao, T. C.; Kalinowski, J.; et al. (2006). "Mapping and comprehensive analysis of the extracellular and cell surface proteome of the human pathogen Corynebacterium diphtheriae". Proteomics. 2006 (6): 2465–2476. doi:10.1002/pmic.200500360. PMID16544277. S2CID22745961.
Riegel, P.; Ruimy, R.; Christen, R.; Monteil, H. (1996). "Species identities and antimicrobial susceptibilities of Corynebacteria isolated from various clinical sources". European Journal of Clinical Microbiology and Infectious Diseases. 15 (8): 657–662. doi:10.1007/bf01691153. PMID8894575. S2CID9243014.