What started as a multi-year collaboration of researchers with varying scientific backgrounds from two lab groups – the Blackwell Lab in the Department of Chemistry and the Lynn Lab in the Department of Chemical and Biological Engineering – resulted in unexpected findings. As detailed in the groups’ new publication, “Identification of small molecules that strongly inhibit bacterial quorum sensing using a high-throughput lipid vesicle lysis assay,” the team utilized an experimental method for observing quorum sensing and discovered new molecules that are released in the process.
In general, the assay detects two actions: the production of virulence factors (i.e., toxic small molecules and proteins) and quorum sensing, Professor Helen Blackwell explained. Quorum sensing describes the process of how bacteria communicate with one another. “Bad” pathogens may create toxins that break phospholipid membranes, and when the membrane ruptures, the lab used fluorophores inside of phospholipid vesicles to create a fluorescent signal.
Chemically, the researchers started by inhibiting the quorum sensing system and looking at the virulence products. Because the assay provides a fluorescent output, when inhibitors were present, the system did not light up, Tom Polaske, a fourth-year graduate student in the Chemical Biology path and co-author on the study, said.
“The final part [of the paper] was to use this assay as a proof of concept to find new compounds,” Polaske said. “We were able to find two new powerful quorum sensing inhibitors of Staphylococcus aureus [a dangerous bacteria that infects humans].”
Currently, other quorum sensing assays exist, but the Blackwell and Lynn Lab collaboration simplified the process.
“It really was a team effort. The three students who pursued this project really worked together as an interdisciplinary team,” Blackwell said. “They learned a lot from each other and taught each other using their different perspectives, so for Dave and me as co-mentors, it was really fun to see them attack this problem.”
The students came from three different disciplines: chemistry, microbiology and materials science.
“Finding ways to communicate was a big learning curve,” Polaske said.
The two lab groups will use their findings to move forward with the project in different directions. Blackwell’s lab will focus on studying the mechanisms of the newly found molecules, while the Lynn lab is focusing on making the assay more straightforward for diagnostic use. Both projects provide pathways to better understand bacterial interactions and how to detect quorum sensing in real-world applications.
“Bacteria are all around us all the time. They play really important roles, so the idea that you need to kill all bacteria all the time is not the best approach,” Blackwell said.
Specifically, Blackwell hopes to improve the ability to accurately target harmful bacteria while keeping helpful bacteria.
“In the future, I think we will have to move toward approaches where we do not kill all the bacteria, but we do targeted strikes at the ones that are causing the biggest problems,” Blackwell said. “Some bacteria do great things for us, so being able to detect which are present and when will allow us to more smartly control bacteria in our environments.