Mycobacterium avium complex
A Microbial Biorealm page on the genus Mycobacterium avium complex
Classification
Higher order taxa
Bacteria (domain); Actinobacteria (phylum); Actinobacteria (class); Actinobacteridae (subclass); Actinomycetales (order); Corynebacterineae (suborder); Mycobacteriaceae (family); Mycobacterium (genus); Mycobacterium avium complex (MAC) (species group).
Species
Includes: Mycobacterium avium
Mycobacterium intracellulare
Also known by: Mycobacterium avium intracelluare (MAI)
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NCBI: Taxonomy |
Description and significance
Mycobacterium avium complex (MAC) contains 28 serovars of two species of mycobacteria: Mycobacterium avium and Mycobacterium intracellulare. These bacterias are slow-growing and cause opportunistic infections to animals, and immunosuppressed humans. MAC is prevalent in the environment and commonly form biofilms in places abundant with water, food, and soil. The biofilms were detected by the use of crystal violet staining and optic and electron microscopy (3). They are usually distinguished by a smooth, wet surface. Biofilms have many negative effects on the humans. The colonies of these different bacterial cells inside our bodies protect them from being attack by our immune system. They can developed in our bodies from the surfaces of medical implants such as urinary catheter or in the cracks of our teeth to form plaque. These bacterias also exist in water and oil pipelines, which slow and even clogged the flow of fluid (7). Studies are being done to identify genes of M. avium that are essential in MAC biofilm formation, with the hope that this information will prevent the bacterial colonization of these biofilms (4).
Genome structure
Mycobacterium avium was completely sequenced on 12/19/2006 at the J. Craig Venter Institute (6). Its entire genome consists of 4,376,040 nucleotides long, with a GC (guanine cytosine) content of 67% and 33% for AT (adenine thymine). Guanine and cytosine are paired with each other by three hydrogen bonds, whereas adenine and thymine have 2 hydrogen bonds that bring them together. Because of the larger number of hydrogen bonds, guanine and cytosine are pulled stronger together, and it would take more energy and a higher melting temperature to separate the two. To determine the DNA genome within a cell, scientists use restriction endonuclease to cleave DNA into many small fragments. The endonucleases usually cleave at an AT rich, because two hydrogen bonds are weaker and require less energy to pull apart than three bonds. between guaning and cytosine The larger number of hydrogen bonds indicate the melting temperature to separate the circular DNA strand for M. avium will be higher than other species with lower number of GC pairs. of 91% of genome are coding regions 3989 proteins. Commonly found in MAC are extrachromosomal DNA in the form of self-replicating plasmids. Studies are being done to determine the significance of plasmids in a M. avium strain (8).
Cell structure and metabolism
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Current Research
Enter summaries of the most recent research here--at least three required
References
Edited by student of Rachel Larsen
