Did you obtain an extract? Summarize the results of your testing and why you choose the tester strain(s) you did.

I was able to obtain an extract for each of my three isolates (#15, 20, and 23) following the extraction procedures we followed over the last few weeks in lab. I chose to use the following tester strains: #1 S. epidermidis (+), #2 E. coli (-), #6 B. subtilis (+), and #7 E. aerogenes (-). I chose these four tester strains because my isolates had shown inhibition previously of #1, #2, and #6 tester strains and then I chose #7 because it was a gram – strain to fulfill the 2 Gram + and 2 Gram – that we testing against in this stage. In my observations from the test extracts, I only saw a ring signaling potential inhibition around my #20 isolate/extract on the #1 S. epidermidis, a Gram + tester strain. There was no other antibiotic activity on the other plates/for the other extracts. I added a photo below of the #20 isolate on the #1 tester strain plate and it is the one circled and labeled “ND 20”. Note that this photo was taken on Thursday, November 1st, a day after Prof. Salvo took the plates out of the incubator and made the observations of antibiotic activity.