Modified experimental protocol to support the study of bacterial quorum sensing in higher education: an investigative activity with Chromobacterium violaceum and Pseudomonas aeruginosa

We developed a modified experimental protocol to support the study of bacterial quorum sensing in practical microbiology classes in higher education. The illustrative version of the experimental protocol was validated through its application in Real-Lab-Day , an active teaching-learning methodology. The target audience was the first-year students in Biomedical Sciences and Fundamental Sciences for Health who are enrolled in the Bacteriology course offered by the Institute of Biomedical Sciences at the University of São Paulo. In the investigative practical activity, the students applied the steps of the scientific method to learn about the complexity of bacterial quorum-sensing circuits using the mutant Δ cviI , obtained from Chromobacterium violaceum strain ATCC 12472, as a colorimetric biosensor. In cross-streak bioassays, the Δ cviI biosensor produced the purple pigment violacein in response to acyl homoserine lactone (AHL) autoinducers released by strains of C. violaceum and Pseudomonas spp. The modified experimental protocol in its illustrative and Standard Operating Protocol versions is available for use as educational resources.