Probing the fractal pattern and organization ofBacillus thuringiensisbacteria colonies growing under different conditions using quantitative spectral light scattering polarimetry

Abstract

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.

Polarisation optics for biomedical and clinical applications: a review

“…Here we briefly summarise common phantoms used for biomedical polarimetric techniques. These techniques include polarised wide-field microscopy 16 , 24 , 183 , polarised light spatial frequency imaging 184 , polarimetric endoscopy 185 – 190 , spectral light scattering polarimetry 18 , 82 , 191 – 193 , polarised fluorescence spectroscopy 194 – 196 , polarised confocal microscopy 197 , polarised Raman-spectroscopy 198 , 199 , polarised super-resolution microscopy 154 , 155 , polarisation sensitive optical coherence tomography 200 – 218 , non-diffraction beam polarimetry (such as Bessel beam based) 219 , polarisation-resolved nonlinear microscopy (including second/third harmonic generation) 220 – 226 , and polarised speckle imaging 213 , 227 (several techniques will be mentioned again in the Discussion). The relationship between incoherence and depolarisation of the light should be kept in mind when considering coherence based polarimetric techniques: they are different but related optical concepts.…”

Mueller polarimetric imaging for surgical and diagnostic applications: a review

“…The retardance contrast between healthy and obstructed regions of the bladder would be potentially useful to guide augmentation surgeries and monitoring the tissue functionality following tissue engineering therapies [21]. Mueller polarimetry or polarimetric imaging has furthermore been used to investigate muscles [146], normal and precancerous human cervix [147], oral [13] and lung tissues [148], radiofrequency ablated porcine myocardial tissue [149], skeletal muscle [150], growth of bacteria colonies [151], skin [152][153][154][155] including melanoma [156], animal tissues [144], bladders [137], the orientation of collagen fibres in 3-D space [23], red blood cell suspensions [157], etc.…”

Biochemical, molecular and in silico characterization of arsenate reductase from pH, salt and arsenic tolerant Bacillus thuringiensis KPWP1

“…In the present study, we have elucidated the ability of Bacillus thuringiensis KPWP1 (Roy et al 2010;Banerjee et al 2013) to tolerate different pH, and different salt and arsenate concentrations. Presence of genes responsible for arsenate resistance mechanism and arsenate reductase activity in KPWP1 have led us to clone and express arsC gene, and puri cation and characterization of ArsC protein of Bacillus thuringiensis KPWP1.…”