Life Cycle of M. tuberculosis !
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Generation time- the time taken for bacteria to double in number during a specific time period. Unlike most bacteria, which some can divide within minutes or hours, Mycobacterium tuberculosis is slow- growing bacteria. It has a doubling time of every 24 to 48 hours. This generation time is extremely slow for bacteria! This means that the mean growth rate constant is 0.02083 to 0.04167 hour per generation.
M. tuberculosis is a heterotroph bacterium meaning they cannot make their own food and must obtain their food source from other organic carbon sources. Specifically, they are parasitic heterotrophic. M. tuberculosis lives on the body surface or inside the body of another host and obtains nutrition directly from the body of the host. In this case, the host is a macrophage. M. tuberculosis utilizes macrophages for its replication and nutrition. It has evolved to avoid the macrophage’s killing mechanism and start replicating within the macrophage. Also, M. tuberculosis can actively cause the macrophage to die and with this way it obtains its food source- the nutrition from the macrophage.
M. tuberculosis is a non-sporulating bacteria. M. tuberculosis reproduces by an asexual process called binary fission. In this method, the parent cell splits producing two independent daughter cells that are identical to the parent cell. They are non-sporulating bacteria.
The above image illustrates binary fission, the asexual process that M. tuberculosis used to reproduce.
https://byjus.com/biology/binary-fission/
M. tuberculosis, an obligate aerobe bacterium, can grow at a temperature from 30- 41oC but grows best at the temperature range of 35-37oC. In a laboratory, Lowenstein- Jensen media with glycerol or sodium pyruvate is used to increase the growth of the colonies. The specimen is incubated at 37oC and colonies appear after 2-3 weeks. The appearance of the colonies on the media is rough, buff to yellowish in color.
The video below shows a time-lapse of M. tuberculosis colonies.
That’s it for the life cycle of Mycobacteria tuberculosis. Come back next for a special post about Mycobacteria tuberculosis.
Citations
http://www.tbonline.info/posts/2016/3/31/description-tb-germ-mycobacterium-tuberculosis-1/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2906719/
http://virology-online.com/Bacteria/Mycobacterium2.htm