Mycobacterium tuberculosis

This article is currently being developed as part of an Eduzendium student project. If you are not involved with this project, please refrain from collaboratively developing it until this notice is removed. Articles that lack this notice, including many Eduzendium ones, welcome your collaboration!

Scientific classification
Kingdom: Bacteria Phylum: Actinobacteria Class: Actinomycetales Order: Corynebacterineae Family: Mycobacteriaceae Genus: Mycobacterium Species: tuberculosis
Binomial name
Mycobacterium tuberculosis

Description and significance

Mycobacterium tuberculosis was first isolated and described in 1882 by Dr. Robert Koch, who later went on to win the Nobel Prize in 1905 for his discovery. Also known as, "Tubercle Bacillus", and Koch's bacillus, M. Tuberculosis is a non-motile, rod shaped bacterium, and the primary cause for the widespread disease tuberculosis.

The World Health Organization estimates that one-third of the world's population is infected with M. Tuberculosis, and that someone new is infected every second. With the emergence of drug resistant strains, both multi drug resistant (MDR) and extensively drug resistant (XDR), controlling the spread of tuberculosis has become a major concern. Since 2006, the WHO's primary strategy in its Stop TB Strategy has been the use of DOTS (Directly Observed Treatment, Short-course). It is estimated to be the most cost effective strategy, only costing $3-$7 to gain a year of health.

Genome structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

- Double stranded circular DNA.

Chart from "http://genolist.pasteur.fr/TubercuList"

DNA Molecule Summary
Total Number of all DNA molecules:	1	100.00%
Total Size of all DNA molecules:	4403837 bp	100.00%
Number of Primary Annotation coding bases:	4069477 bp	92.40%
Number of G+C bases:	2889216 bp	65.60%

Primary Annotation Summary
Total genes:	4294	100.00%
Protein coding genes:	4246	98.88%
Genes assigned a role category:	2317	54.56%
Genes not assigned a role category:	2	0.04%
Conserved hypothetical genes:	655	15.42%
Hypothetical genes:	1272	29.95%
tRNA genes:	45	1.04%
rRNA genes:	3	0.06%

Cell structure and metabolism

(Temporary General Outline)

- Obligate Aerobe: Explains why it infects the upper lobes of the lungs

- Slow rate of growth compared to other bacteria (about 15-20 hours)

- Non-motile rod shaped

- Size: ~2-4 um in length and 0.2-0.5 um in width

- Acid-fast staining is used (specifically Ziehl-Neelsan Stain)

- Cell wall: peptidoglycan but note 60% lipid (Mycolic Acid, Cord Factor, Wax-D) High lipid percentage results in a lot of interesting properties: (impermeability to stain; different kinds of resistances (antibiotics, osmotic lysis, acidic and alkaline compounds, oxidation).

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

(Temporary General Outline)

- Major cause of tuberculosis (can link to tuberculosis page later)

- Binding to mannose receptors (for entry into cell)

- Ability to prevent lysosome from fusing with phagosome, as a result prevents the destruction of the bacteria.

- Slow generation may actually help the bacteria from being detected by the immune system.

- Cell wall construction is 60% lipid. Lot of different types of resistances.

- Antigen 85: binds to fibronectin and may help in protecting the bacteria from the immune system.

- Interference with oxygen intermediates

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Summaries to come

Pubmed article about BCG vaccine

Pubmed article about the discovery of lipolytic enzymes which may be involved with virulence

Article concering multi-drug resistant mycobacterium tuberculosis

References

1. www.textbookofbacteriology.net

2. Honaker RW, Stewart A, Schittone S, Izzo A, Klein MR, Voskuil MI "BCG vaccine strains lack narK2 and narX induction and exhibit altered phenotypes during dormancy." Infect Immun. 2008 Mar 24

3. Côtes K, Bakala N'goma JC, Dhouib R, Douchet I, Maurin D, Carrière F, Canaan S. "Lipolytic enzymes in Mycobacterium tuberculosis." Appl Microbiol Biotechnol. 2008 Apr;78(5):741-749. Epub 2008 Feb 29.

4. Raphael C. Y. Chan, Mamie Hui, Edward W. C. Chan, T. K. Au, Miu L. Chin, Chun K. Yip1, Carrie K. W. AuYeang, Christina Y. L. Yeung1, Kai M. Kam, Peter C. W. Yip and Augustine F. B. Cheng. "Genetic and phenotypic characterization of drug-resistant Mycobacterium tuberculosis isolates in Hong Kong" Journal of Antimicrobial Chemotherapy 2007 59(5):866-873.