Week Three

This week we finished gram staining the bacterial growth that was found on the plastics labeled 1 through 6. Next we will be able to get a closer look at the bacteria through looking at its cell wall composition and making a determination of whether it's a gram negative or gram positive bacteria.
Some of these are new concepts and procedures for me, so I'm going to delve into the basics of my understanding of it. And this way I can come back later to look over it if I need to. If there's any other relevant info I missed, please feel free to share.

This is the slide for Plastic # 5
(plate 2), plastic sample # 5.
Note, the red/pink color
of the sample.

Collectively, we reasoned that the bacteria growing on the plastics are gram negative. One indicator of that for me was, while rinsing the samples with the decolorizing agent the crystal violet and iodine complex would wash away easily. Since gram positive bacteria have multi-layered peptidoglycan cell walls, the crystal violet & iodine would've binded and stained purple instead of washing away.
Another indicator that someone in my group pointed out was that the safronin was more prominent in our samples. I read that in a gram positive bacteria, the purple would have stayed in the sample. And for gram negative a pink/red stain should result. Next week we'll be looking at the slides and hopefully make a better determination.