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Journal of Biomedical Optics • Open Access

Modeling light propagation through bacterial colonies and its correlation with forward scattering patterns
Author(s): Euiwon Bae; Nan Bai; Amornrat Aroonnual; J. Paul Robinson; Arun K. Bhunia; E. Daniel Hirleman

Paper Abstract

Bacterial colonies play an important role in the isolation and identification of bacterial species, and plating on a petri dish is still regarded as the gold standard for confirming the cause of an outbreak situation. A bacterial colony consists of millions of densely packed individual bacteria along with matrices such as extracellular materials. When a laser is directed through a colony, complicated structures encode their characteristic signatures, which results in unique forward scattering patterns. We investigate the connection between the morphological parameters of a bacterial colony and corresponding forward scattering patterns to understand bacterial growth morphology. A colony elevation is modeled with a Gaussian profile, which is defined with two critical parameters: center thickness and diameter. Then, applying the scalar diffraction theory, we compute an amplitude modulation via light attenuation from multiple layers of bacteria while a phase modulation is computed from the colony profile. Computational results indicate that center thickness plays a critical role in the total number of diffraction rings while the magnitude of the slope of a colony determines the maximum diffraction angle. Experimental validation is performed by capturing the scattering patterns, monitoring colony diameters via phase contrast microscope, and acquiring the colony profiles via confocal displacement meter.

Paper Details

Date Published: 1 July 2010
PDF: 11 pages
J. Biomed. Opt. 15(4) 045001 doi: 10.1117/1.3463003
Published in: Journal of Biomedical Optics Volume 15, Issue 4
Show Author Affiliations
Euiwon Bae, Purdue Univ. (United States)
Nan Bai, Purdue Univ. (United States)
Amornrat Aroonnual, Ctr. for Food Safety Engineering (United States)
J. Paul Robinson, Purdue Univ. (United States)
Arun K. Bhunia, Ctr. for Food Safety Engineering (United States)
E. Daniel Hirleman, Purdue Univ. (United States)

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