This is an old revision of this page, as edited by 142.22.186.7 (talk) at 16:11, 16 October 2006 (→Identification). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 16:11, 16 October 2006 by 142.22.186.7 (talk) (→Identification)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)
| Mycobacterium tuberculosis | |
|---|---|
| |
| M. tuberculosis bacteria | |
| Scientific classification | |
| Kingdom: | Bacteria |
| Phylum: | Actinobacteria |
| Order: | Actinomycetales |
| Suborder: | Corynebacterineae |
| Family: | Mycobacteriaceae |
| Genus: | Mycobacterium |
| Species: | M. tuberculosis |
| Binomial name | |
| Mycobacterium tuberculosis Zopf 1883 | |
Mycobacterium tuberculosis is the bacterium that causes most cases of tuberculosis. It was first described on March 24, 1882 by Robert Koch, who subsequently received the Nobel Prize in physiology or medicine for this discovery in 1905. The M. tuberculosis genome was sequenced in 1999.
Physiology
M. tuberculosis is an obligate aerobe (Gram positive mycobacterium). While mycobacteria do not seem to fit the Gram positive category from an empirical standpoint (i.e. they do not retain the crystal violet stain), they are classified as such due to their lack of an outer cell membrane. M. tuberculosis divides every 15 to 20 hours—extremely slowly compared to other bacteria, which tend to have division times measured in minutes (for example, E. coli can divide roughly every 20 minutes). It is a small, rod-like bacillus that can withstand weak disinfectants and can survive in a dry state for weeks but can grow only within a host organism.
Identification
M. tuberculosis is identified microscopically by its staining characteristics: it retains certain stains after being treated with acidic solution, and is thus classified as an "acid-fast bacillus" (AFB). In the most common staining technique, the Ziehl-Neelsen stain, AFB are stained a bright red, which stands out clearly against a blue background. Acid-fast bacilli can also be visualized by fluorescent microscopy, and by auramine-rhodamine stain. The reason for the acid-fast staining seen in mycobacteria is because of its thick waxy cell wall.
This waxy cell wall also is responsible for the typical caseous granuloma formation in tuberculosis. The component responsible is called the cord factor. M. tuberculosis bacteria are difficult to grow. Lowenstein-Jensen media have traditionally been used for this purpose, but faster results can now be obtained using Middlebrook media. and there gay cause i said so
References
- ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
{{cite book}}:|author=has generic name (help);|edition=has extra text (help)CS1 maint: multiple names: authors list (link) - Cole ST; Brosch R; Parkhill J; et al. (1998). "Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence". Nature. 393: 537–544.
{{cite journal}}: Explicit use of et al. in:|author=(help)CS1 maint: multiple names: authors list (link) - Camus JC; Pryor MJ; Medigue C; Cole ST. (148). "Re-annotation of the genome sequence of Mycobacterium tuberculosis H37Rv". Microbiology. 2002: 2967–2973.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Madigan, Michael; Martinko, John (editors) (2005). Brock Biology of Microorganisms (11th ed. ed.). Prentice Hall. ISBN 0-13-144329-1.
{{cite book}}:|author=has generic name (help);|edition=has extra text (help)CS1 maint: multiple names: authors list (link)
External links
- BioHealthBase Bioinformatics Resource Center Database of Mycobacterium tuberculosis genome sequences and related information.