A Simple Biosensor Based on Streptavidin-HRP for the Detection of Bacteria Exploiting HRPs Molecular Surface Properties

Bacterial contamination of water and food sources is still a major source of diseases. Early detection of potential pathogens is key to prevent their spreading and severe health risks. Here, we describe a fast, low-cost detection assay based on horseradish peroxidase (HRP) conjugated to streptavidin for the direct identification of bacteria. Streptavidin can bind to bacterial cells due to its high affinity for biotin, a natural component of microbial cell surfaces. Upon binding to bacteria, the HRP converts a chromogenic substrate, resulting in a visible color change. In the present study, we evaluated different detection platforms regarding their compatibility with the detection principle. To reduce background signals and increase the sensitivity of HRP-based assays, the binding of HRP to surfaces and biomolecules was intensively investigated. The final assay successfully detected the most relevant bacterial strains in drinking water, such as Escherichia coli, Klebsiella pneumonia, and Enterobacter cloacae.