Mycobacterium (redirected from Group I-IV mycobacteria)

mycobacterium

Any of the rod-shaped bacteria that make up the genus Mycobacterium. The two most important species cause tuberculosis and leprosy in humans; another species causes tuberculosis in both cattle and humans. Some mycobacteria live on decaying organic matter; others are parasites. Most are found in soil and water in a free-living form or in diseased tissue of animals. Various antibiotics have had some success against mycobacterium infections.

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Mycobacterium 

a genus of bacteria, related to actinomycetes; it differs from true bacteria in a number of ways. The young vegetative cells are rodlike (0.5–0.8 × 2.2 microns); they are capable of branching and acquiring V or Y shapes. In old cultures spherical cells predominate. Mycobacteria, which do not form endospores, are nonmotile, gram-positive, and strictly aerobic. They reproduce mainly by dividing and budding. Mycobacteria contain carotenoids, and, as a result, their colonies are often pigmented (yellow, orange, or red). Owing to their cell composition (including lipides and wax), some myco-bacteria, in contrast to other bacteria, are acid-fast.

Mycobacteria are widely distributed in soils and are active in the mineralization of plant remains. Some species of Mycobacterium are nitrogen-fixing microorganisms; others are capable of metabolizing the carbohydrates of petroleum and natural gas and, when cultured, accumulate protein, which is used for fodder and other purposes. Some species of Mycobacterium are pathogenic to humans (for example, mycobacteria are the causative agents of tuberculosis and leprosy).

A. A. IMSHENETSKII