Detecting and correlating bacterial populations to visual color change of polydiacetylene-coated filters.

Membrane filters were coated with 10,12-pentacosadiynoic acid (PCDA) then polymerized on the filter for rapid bacterial detection and quantification. The polymerized PCDA (pPDCA)-coated filter changed color in response to Salmonella Typhimurium and Escherichia coli but not to Listeria innocua. The time required for color change of pPCDA-coated filters was determined by a visual panel. A simple linear regression model was generated to fit the observed data and was validated with goodness of fit analysis and residual analysis. The pPCDA-filter method estimated Salmonella Typhimurium populations of 8 to 3 log CFU ml-1 within 1.5-7.5 h, respectively.