Enhanced sampling of bacteria and their biofilms from food contact surfaces with robust cationic modified swabs

The swab sampling method combined with detection approaches is a common approach used to monitor pathogenic microbes in food facilities and to determine the adequateness of regular cleaning and sanitation processes. Thus, the efficiency of a swab material for both the capture and release of bacteria has a significant impact on the detection of pathogens. A novel functionalized cotton swab was developed based on cationic functionalization of the cotton swab for improving the sampling of bacteria from surfaces. The cationic modified swab was fabricated using UV-induced grafting of cationic monomer (METAC) onto a regular cotton swab. The prepared cationic cotton swabs displayed a persistent positive charge regardless of the pH conditions. The cationic swabs demonstrated 150–200% enhancement in the swab performance for Gram-positive and Gram-negative bacteria under any sampling conditions compared to the regular cotton swab as well as a significant enhancement in the bacteria sampling at the low bacterial concentrations. Furthermore, the cationic cotton swabs showed significant improvement at least 4 folds in the sampling performance of the bacterial biofilm from the stainless-steel surfaces compared to the cotton swabs. These results illustrate the role of modified swabs in enhancing the sampling of bacteria from contact surfaces and their potential impact on improved monitoring of microbial contamination and verification of surface sanitization.

     

Nanophotonic Device in Combination with Bacteriophages for Enhancing Detection Sensitivity of Escherichia coli in Simulated Wash Water

Among various approaches to control and monitor cross-contamination of fresh produce, a biosensor that can rapidly detect the presence of a specific bacterium in wash water or on fresh produce can be effective. This research demonstrates the development of a rapid biosensor based on a combination of a nanophotonic device and the bacteriophage T7 for the detection of Escherichia coli without the need for culturing or nucleic acid extraction. This biosensor platform is based on bacteriophage mediated specific lysis of target bacteria and release of β-galactosidase. The enzyme could be further detected by a nanophotonic device that amplifies the fluorescent signal, therefore allowing better sensitivity. Production of β-galactosidase is induced by isopropyl β-D-1-thiogalactopyranoside (IPTG) and the enzyme is then released by bacteriophage lysis, which is detected by the nanophotonic device using a fluorescent enzyme substrate resorufin β-D-galactopyranoside. Using this approach, the results demonstrated successful detection of 10 CFU mL^?1 of E. coli BL21 in simulated spinach wash water within 8?hours. Specificity of the assay was demonstrated with negative controls including Pseudomonas fluorescens and Listeria innocua.