Today we pulled out our first plates of Serratia marcescans which some of the students used to redo the antiseptics/disinfectants lab. The cultures were bright red and fascinated the students. We used them to make wet mount slides and some of the kids chose to do Gram stains. They expected the bacteria themselves to be red, but they were gray, rod-shaped bacteria which Gram-stained negative. The red is just a pigment produced by the bacteria. I wonder why they produce that pigment. I'm looking, but haven't gotten the answer to that question yet. They are motile, though and some of ours could be seen moving since we did not heat set them in the wet mount slide. The kids loved it!
The zones of inhibition part of the lab was also interesting today. We pooled all the data and the hydrogen peroxide was again very effective (shown in the bottom quadrant in the picture above) as was the iodine-based pre-surgical sterilizer someone had brought from a hospital. Hand sanitizer was not very effective at all, much to the dismay of the students.
No comments:
Post a Comment