Abstract
Investigations into bacterial quorum sensing (QS), a form of communication based on the production and detection of quorum sensing molecules (QSMs) to coordinate gene expression in a population dependent manner, offer a unique window to study the molecular underpinnings of microbial behavior and host interactions. Although well studied in select pathogenic bacteria, the role of QSMs produced by commensal gut microbes in shaping microbiome structure and host-microbiome interactions remains poorly understood. In this body of work, a microbial whole-cell biosensor (MWCB) was engineered to enable the selective, sensitive, stable, and reproducible detection of the novel QSM, 3,5-dimethylpyrazine-2-ol (DPO). Following detection of DPO in healthy rodent and human stool, the QSM profile of a variety of commensal gut bacteria was queried and their subsequent effects on emergent microbiome communities was observed. It was discovered that a wide variety of commensal gut bacteria are capable of producing DPO and Autoinducer-2 (AI2), and that these DPO producing strains appear to localize to the lower gastrointestinal tract. These findings, along with implications and recommendations for further study, are herein enclosed.