Identification and characterization of bacteria on surfaces using light scattering

In the past 30 years, the pattern and intensity of scattered light from small illuminated bio-features suspended in fluids have been analyzed to obtain information on feature size and composition. However, recent advances by the investigators related to rapid, non-invasive detection of sub-micron particles on silicon wafers in semiconductor processing suggest an attractive new approach to the problem of surface bio-feature detection and characterization. Our objective is to develop a rapid light scattering sensory method for the detection and identification of surface bacteria microcolonies to meet the needs for rapid identification techniques by the food and health industries. Scatterometer measurements of light scattering from Listeria monocytogenes ATCC 191 13 and Listeria innocua ATCC 33090 microcolonies on enriched agar plates has been performed. The prediction of light scattering from bacteria cells on surfaces has also been conducted using numerical modeling based on the discrete-dipole approximation. These studies show the variation of light scattering for various shaped and sized bacteria.