Human Practices: Gold Medal Requirements

In order to aim for the Gold Medal requirement in Human Practices, we tried to integrate our Human Practices whenever designing or interpreting experiments. After learning about the lack of available information on AHL safety, we felt that the biosafety concerns resulting from the actual AHL molecules was an area worth investigating. We decided to develop a safe disposal protocol that could be used by research laboratories and be based on standard EH&S safety procedures. This meant the use of a 10% bleach solution as well as autoclaving. One paper that was especially useful to this experiment was “Reaction of Acylated Homoserine Lactone Bacterial Signaling Molecules with Oxidized Halogen Antimicrobials” by S.A. Borchardt, in which they investigated the decomposition of AHLs by Clorox bleach. We learned from this paper that 3-oxo AHLs are easily degraded by bleach (due to the reactive beta ketone), but other AHLs were not.

We decided to apply the standard EH&S bleach concentration(10%) to extracted and reseeded AHL solutions and allowed them to sit for 10, 20, and 30 minutes. We also autoclaved AHL solutions and tested these reseeded solutions. Then, F2620 inductions were attempted and measured inside a plate reader for GFP. This was done directly after the F2620 inductions test that we conducted for our main project to characterize our ten Senders, and was an extension of that project that we felt would be a good way to test our safe disposal plan.

After gathering data from the bleach and autoclave experiments and compiling it with the Borchardt findings, we developed suggestions for the proper disposal of each of the AHL Senders that we constructed and tested, primarily dependent on the structure of the acyl tail found in each AHL. These suggestions and other integrated practices are found on the Integrated Human Practices page.