Dynamics of Deinococcus radiodurans
Under Controlled Growth Conditions
Sidhartha S. Jena 1*, Hiren M. Joshi 2, K. P.V. Sabareesh 3, B. V.R. Tata 3 and T. S. Rao 2
1 indira gandhi center for atomic research
2 Bhabha Atomic Reseach Center, Kalpakkam
3 Indira Gandhi center for Atomic Research
* To whom correspondence should be addressed. E-mail: sid{at}igcar.gov.in.
Submitted on April 5, 2006
Revised on April 28, 2006
Accepted on 16 June 2006
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Abstract |
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Deinococcus radiodurans is a potent radiation resistant bacterium with immense potential in nuclear waste treatment. In this investigation, the translational and rotational dynamics of dilute suspensions of D. radiodurans cultured under controlled growth conditions, was studied by the polarized and depolarized dynamic light scattering (DLS, DDLS) techniques. Additionally, confocal laser scanning microscopy (CLSM) was used for characterizing the cultured samples and also for identification of D. radiodurans dimer, tetramer and multimer morphologies. The data obtained showed translational diffusion coefficients (DT) of 1.2 x 10 -9, 1.97 x 10 -9, and 2.12 x 10 -9 cm2 /sec, corresponding to an average size of 3.61, 2.22, and 2.06 mm respectively for live multimer, tetramer, and dimer forms of D. radiodurans. Depolarized DLS experiments showed very slow rotational diffusion coefficients (DR) of 0.182 /sec for dimer and 0.098 /sec for tetramer morphologies. No measurable rotational diffusion was observed for multimer forms. Polarized DLS measurements on live D. radiodurans confirmed that the bacterium is non-motile in nature. The dynamics of the dead dimer and tetramer D. radiodurans were also studied using polarized and depolarized DLS experiments and compared with the dynamics of live species. The dead cells were slightly smaller in size when compared to the live cells. However, no additional information could be obtained for dead cells from the polarized and depolarized dynamic light scattering studies.
Key Words:
Confocal Microscopy, Deinococcus radiodurans, Depolarized Dynamic Light Scattering, Dynamic Light Scattering, Rotational Diffusion Coefficient, Translational Diffusion Coefficient
