Biochemical signature assay for use in a biosensor platform to detect bacteria in drinking water biofilms

The objective of the study was to identify the enzymatic-biochemical (enz-bio) signatures of Escherichia coli and Salmonella for rapid detection of these bacteria in drinking water biofilms. The relative potency of lipophilic, glucosidic, and proteolytic activities in biofilms containing single bacterial species and mixture of different bacterial was used to identify the enz-bio signatures of Escherichia coli and Salmonella. The enz-bio signatures identified were: Lipophilic < Glucosidic < Proteolytic (for Escherichia coli); and Glucosidic = Lipophilic < Proteolytic (for Salmonella). The enz-bio assays were performed sequentially for detecting Escherichia coli and Salmonella in pure and mixed biofilm cultures formed on the coupons incubated in a batch reactor. The results obtained were substantiated by culture-based assays indicating comparable data. The enz-bio sensing method described here is a proof of principle and the results of this study provide a platform for the fabrication of a biosensor for bacterial detection in biofilms. The detection time required for the biosensor platform versus culture methods ranged from 10 to 120 min and 24 to 48 h, respectively.