Since this was the last week of the quarter, we didn’t require the students to blog as in the previous 9 weeks. Also, mostly we recapped what had happened in the class and discussed various assignments. But the students did measure the antibiotic resistance of their strains, and we also had a powerful demonstration of the utility of social media in science.
So the previous week the students plated out their isolates (from liquid culture) and placed antibiotic resistance disks on the plate. We were testing both Chloramphenicol and Enrofloxacin, both of which are used to treat Chlamydia infection in koalas. In addition, we tested Ampicillin, Tetracycline, Penicillin, Gentamicin, Neomycin, and Streptomycin. The students measured the inhibition zones and recorded that information in the lab notebook. The results were a mixed bag; some strains didn’t grow well, some zones of inhibition has gotten so large that it was hard to differentiate between antibiotics. But in the end we got a lot of useful information, including evidence that at least one of the putative tannin-degrading bacteria is susceptible to the antibiotics used to treat Chlamydia.
However, one strain showed a very strange inhibition pattern, shown in the picture below. None of the instructors had a good explanation so we took to Twitter. During the next hour, dozens of responses, ideas, and hypotheses poured in. A professor from another university even offered cookies to students from his class if they could give plausible explanations for the observed pattern. At the end of class we put a Twitter feed up on the projector and showed the students the discussion and we talked about the various hypotheses. The students were clearly impressed that in such a short time we had connected with so many different people, from around the world, to think about this one humble plate. Here is a partial Storify of that discussion. For some reason we are having trouble with Storify in blog posts… but fear not, I plan on writing an entire blog post about just this topic.