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The PknI and DacB2 double deletion mutant of Mycobacterium tuberculosis leads to alteration of cell morphology and susceptibility to antibiotics


Mycobacterium tuberculosis is a slow growing infectious pathogen. It takes twenty hours for a single cell to divide into two. Its cell division is complex involving a number of proteins. Although, the physiological roles of several serine/threonine phosphorylation connected to cell division and peptidoglycan synthesis have been studied the exact mechanism is not clear. PknI and DacB2 located in a same cluster have been shown to play a role in cell division and cell wall synthesis. The aim of this present study was to construct the double deletion mutant (DKO) of PknI and DacB2 and study the effect on cell morphology and antibiotic susceptibility.


Specialized phage transduction method was used to construct DKO strain of PknI and DacB2. The cell morphology was observed in solid agar plate, light microscopy and electron microscopy. The MIC was determined by resazurin based microplate assay.


The DKO was confirmed by PCR and southern blotting methods. The light and electron microscopy study revealed that DKO showed irregular shape and smoother colonies in comparison to M. tuberculosis H37Rv. The DKO was more susceptible to isoniazid compared to M. tuberculosis H37Rv and DKO showed the same sensitivity pattern as H37Rv strain to other drugs.


In the present study, we have successfully constructed a novel DKO strain of Mycobacterium tuberculosis. PknI and DacB2 were found to have a role in maintaining cell morphology and isoniazid resistance.

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Correspondence to Srinivasan Kandasamy.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Kandasamy, S., Narayanan, S. The PknI and DacB2 double deletion mutant of Mycobacterium tuberculosis leads to alteration of cell morphology and susceptibility to antibiotics. BMC Infect Dis 14, E22 (2014).

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  • Tuberculosis
  • Cell Morphology
  • Isoniazid
  • Mycobacterium Tuberculosis
  • Peptidoglycan