Share Email Print
cover

Journal of Biomedical Optics • Open Access

Probing the fractal pattern and organization of Bacillus thuringiensis bacteria colonies growing under different conditions using quantitative spectral light scattering polarimetry
Author(s): Paromita Banerjee; Jalpa Soni; Harsh Purwar; Nirmalya Ghosh; Tapas K. Sengupta

Paper Abstract

Development of methods for quantification of cellular association and patterns in growing bacterial colony is of considerable current interest, not only to help understand multicellular behavior of a bacterial species but also to facilitate detection and identification of a bacterial species in a given space and under a given set of condition(s). We have explored quantitative spectral light scattering polarimetry for probing the morphological and structural changes taking place during colony formations of growing Bacillus thuringiensis bacteria under different conditions (in normal nutrient agar representing favorable growth environment, in the presence of 1% glucose as an additional nutrient, and 3 mM sodium arsenate as toxic material). The method is based on the measurement of spectral 3×3 Mueller matrices (which involves linear polarization measurements alone) and its subsequent analysis via polar decomposition to extract the intrinsic polarization parameters. Moreover, the fractal micro-optical parameter, namely, the Hurst exponent H , is determined via fractal-Born approximation-based inverse analysis of the polarization-preserving component of the light scattering spectra. Interesting differences are noted in the derived values for the H parameter and the intrinsic polarization parameters (linear diattenuation d , linear retardance δ , and linear depolarization Δ coefficients) of the growing bacterial colonies under different conditions. The bacterial colony growing in presence of 1% glucose exhibit the strongest fractality (lowest value of H ), whereas that growing in presence of 3 mM sodium arsenate showed the weakest fractality. Moreover, the values for δ and d parameters are found to be considerably higher for the colony growing in presence of glucose, indicating more structured growth pattern. These findings are corroborated further with optical microscopic studies conducted on the same samples.

Paper Details

Date Published: 5 March 2013
PDF: 11 pages
J. Biomed. Opt. 18(3) 035003 doi: 10.1117/1.JBO.18.3.035003
Published in: Journal of Biomedical Optics Volume 18, Issue 3
Show Author Affiliations
Paromita Banerjee, Indian Institute of Science Education and Research Kolkata (India)
Jalpa Soni, Indian Institute of Science Education and Research Kolkata (India)
Harsh Purwar, Indian Institute of Science Education and Research Kolkata (India)
Nirmalya Ghosh, Indian Institute of Science Education and Research Kolkata (India)
Tapas K. Sengupta, Indian Institute of Science Education and Research Kolkata (India)


© SPIE. Terms of Use
Back to Top