What more can we possibly know about our bacteria? There are many characteristics that we still have yet to discover for identification. One prominent characteristic used to define and identify bacteria is the presence of a capsule. Today we decided to explore this aspect of structure in our bacteria; we made a capsule stain!
Why would our bacteria need a capsule? Well, in order for the bacteria to not be phagocized (cellular eating) by the leukocytes (white blood cells) in the body it produces a capsule made of glycocalyx. However, only some bacteria are capable of this, which helps in classification of bacteria.
Preparing a Capsule Stain:
First, we followed a procedure for producing a Negative stain, which allows us to create an opaque background to view the specimen upon. To do this we used to stain Nigrosin, and we placed a drop of it on a corner of a clean slide. Then, using the aseptic technique, we transferred a drop of our bacteria into the Nigrosin and mixed it well with the inoculating loop. After, using a clean slide, we spread the drop throughout the surface of the first slide thinly and evenly.
After the slides were completed, we let them air dry.
It was time to then prepare the capsule stain. We placed our newly stained slides upon the slide drying rack suspended over the sink. To continue the process, we used Crystal Violet stain over the Nigrosin to cover our specimens completely. We let the Crystal Violet sit for about a minute, and then we rinsed the excess dye with water. One must be careful not to rinse too long or the entire staining will be removed since the bacteria was not heat-fixed in the staining process. After,we blotted the slide dry with Bibulous Paper.
NOTE: BE CAREFUL NOT TO STAIN HANDS IN THE PROCESS OR YOU WILL BE PURPLE FOR A VERY LONG TIME! (found from personal experience)
We viewed the specimens under the oil immersion lens in order to avoid refraction of the light; this increased resolution.
Capsule Staining for "F":
Our Unknown did not have a capsule, as seen by the photomicrographs above. A capsule is viewed under a microscope as a halo of transparent matter surrounding the bacteria. Since, there is no transparent sections surrounding the bacteria, no capsules are found to be present. We have become one step closer to identifying our bacteria!
Capsule Stain of Our Environmental Sample:
Our environmental sample also has survived without a capsule. The clear specs found on our slides are not capsules. Capsules clearly surround the bacteria much like in this picture:
This picture is courtesy of <http://iws2.collin.edu/dcain/CCCCD%20Micro/capsule_stain.htm>. This website explains capsule staining as well, if you have anymore questions. Notice the thick circular halos located around the bacteria. This is how a slide would appear with capsules present using this staining technique.
Join us next week for more staining, identifying, and FUN!
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