Asymmetric cell division in Mycobacterium tuberculosis and its unique features

Vijay, Srinivasan and Nagaraja, Mukkayyan and Sebastian, Jees and Ajitkumar, Parthasarathi (2014) Asymmetric cell division in Mycobacterium tuberculosis and its unique features. In: ARCHIVES OF MICROBIOLOGY, 196 (3). pp. 157-168.

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Abstract

Recently, several reports showed that about 80 % of mid-log phase Mycobacterium smegmatis, Mycobacterium marinum, and Mycobacterium bovis BCG cells divide symmetrically with 5-10 % deviation in the septum position from the median. However, the mode of cell division of the pathogenic mycobacterial species, Mycobacterium tuberculosis, remained unclear. Therefore, in the present study, using electron microscopy, fluorescence microscopy of septum- and nucleoid-stained live and fixed cells, and live cell time-lapse imaging, we show the occurrence of asymmetric cell division with unusually deviated septum/constriction in 20 % of the 15 % septating M. tuberculosis cells in the mid-log phase population. The remaining 80 % of the 15 % septating cells divided symmetrically but with 2-5 % deviation in the septum/constriction position, as reported for M. smegmatis, M. marinum, and M. bovis BCG cells. Both the long and the short portions of the asymmetrically dividing M. tuberculosis cells with unusually deviated septum contained nucleoids, thereby generating viable short and long cells from each asymmetric division. M. tuberculosis short cells were acid fast positive and, like the long cells, further readily underwent growth and division to generate micro-colony, thereby showing that they were neither mini cells, spores nor dormant forms of mycobacteria. The freshly diagnosed pulmonary tuberculosis patients' sputum samples, which are known for the prevalence of oxidative stress conditions, also contained short cells at the same proportion as that in the mid-log phase population. The probable physiological significance of the generation of the short cells through unusually deviated asymmetric cell division is discussed.

Item Type:	Journal Article
Publication:	ARCHIVES OF MICROBIOLOGY
Publisher:	SPRINGER
Additional Information:	Copyright for this article belongs to the SPRINGER, USA
Keywords:	Asymmetric septum; Asymmetric cell division; Mycobacterium tuberculosis; Short cell; Nucleoid; Symmetric cell division
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	11 Apr 2014 10:03
Last Modified:	11 Apr 2014 10:03
URI:	http://eprints.iisc.ac.in/id/eprint/48842

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