Reprogramming Probiotic <i>Lactobacillus reuteri</i> as a Biosensor for <i>Staphylococcus aureus</i> Derived AIP‑I Detection

Gram-positive <i>Staphylococcus aureus</i> infection that results in pneumonia, urinary tract infection, and in severe cases, sepsis, has recently been classified as a serious threat to public health. Rapid and cost-effective detection of these infections are costly and time-consuming. Here, we present probiotic lactic acid bacteria engineered to detect autoinducer peptide-I (AIP-I), a quorum sensing molecule produced by <i>Staphylococcus</i> sp. during pathogenesis. We achieved this by adapting the well-characterized <i>agr</i> quorum sensing (<i>agr</i>QS) from <i>Staphylococcus aureus</i> into <i>Lactobacillus reuteri</i>. The engineered biosensor is able to detect AIP-I levels in the nanomolar to micromolar range. We further investigated the function of the biosensor to detect real-time changes in AIP-I levels to understand the dynamics of <i>Staphylococcus aureus</i> under various strenuous conditions. The developed sensors would be useful for detection of <i>Staphylococcus</i> contamination in hospital settings and for high-throughput drug screening