Nothing, absolutely NOTHING worked today in lab as I had expected! In fact, the only positive I can think of about our results today might be to let the kids see that in a real science lab, where you are doing real research, things OFTEN go WRONG!
To begin, in our antibiotic resistance lab, there were NO zones of inhibition in anyone's plates. I have no idea why that might be. The antibiotics were all new and had been stored in the refrigerator, so should have been very effective. I did ask the students to brainstorm possible things we could try to do differently. They hypothesized that if we had inoculated the plates on the same day that the antibiotics were placed on the plates, that might have made a difference. Someone else said that maybe we should have wet the antibiotic disks, a fact that was supported by several plates which had developed "cracks" in the agar emanating from the antibiotic disk which seemed to suggest that the disks had absorbed the water from the nearby agar. So, I had 20 agar plates left that we could use. Students who wanted to reinoculated those plates and either placed disks on them as before or wet them with some distilled water. I had a few drops of sterile water in the aluminum foil which held the inoculating loops I had sterilized, so one group dipped their disks in the sterile water instead of using distilled water. I guess we will see if any of this changes the outcome of this lab so I'll know how to proceed next year. If nothing changes, I probably will not do this lab next year.
On the switchgrass front, only two or three of the transfers showed any growth today and probably one or two are contaminated. We will continue to watch them for the next little while. So that all students will have a plate of fungus to look at when we study fungi in the next couple weeks, I let them all make transfers out of the fully developed plates I have of two of the fungi I brought with me from UT. I really want them to be able to see the fruiting bodies and make slides of the spores if at all possible. This switchgrass pathogen project may be too ambitious for a large group of high school students, especially without Rifampicin to inhibit bacterial growth.
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The redo worked a little better than the original attempt at this lab. Some students tried inoculating the plate on the same day they added antibiotic disks. These plates did show some zones of inhibition. Some students tried adding a drop of water (distilled or sterile with different lab groups). I really couldn't tell a whole lot of difference with that change. Next semester, we will inoculate the plates at the same time we add the antibiotic, although I still don't understand why it didn't work as expected the first time.
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