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16 February 2007 Quantification of morphology of bacterial colonies using laser scatter measurements and solid element optical modeling
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Traditional biological and chemical methods for pathogen identification require complicated sample preparation for reliable results. Optical scattering technology has been used for identification of bacterial cells in suspension, but with only limited success. Our published reports have demonstrated that scattered light based identification of Listeria colonies growing on solid surfaces is feasible with proper pattern recognition tools. Recently we have extended this technique to classification of other bacterial genera including, Salmonella, Bacillus, and Vibrio. Our approach may be highly applicable to early detection and classification of pathogens in food-processing industry and in healthcare. The unique scattering patterns formed by colonies of different species are created through differences in colony microstructure (on the order of wavelength used), bulk optical properties, and the macroscopic morphology. While it is difficult to model the effect on scatter-signal patterns owing to the microstructural changes, the influence of bulk optical properties and overall shape of colonies can be modeled using geometrical optics. Our latest research shows that it is possible to model the scatter pattern of bacterial colonies using solid-element optical modeling software (TracePro), and theoretically assess changes in macro structure and bulk refractive indices. This study allows predicting the theoretical limits of resolution and sensitivity of our detection and classification methods. Moreover, quantification of changes in macro morphology and bulk refractive index provides an opportunity to study the response of colonies to various reagents and antibiotics.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Silas Leavesley, Bülent Bayraktar, Murugesan Venkatapathi, E. Dan Hirleman, Arun K. Bhunia, J. Paul Robinson, Richard Hassler, Linda Smith, and Bartek Rajwa "Quantification of morphology of bacterial colonies using laser scatter measurements and solid element optical modeling", Proc. SPIE 6446, Biomedical Applications of Light Scattering, 64460E (16 February 2007);

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