Hi!
Of course! We are so happy to help out!
In order to prove that he got more colonies for the dogs, did you guys figure out a method to do that? I know you are using the nutrient media, so you guys must be colony counting, or just counting the bacterial colony "dots" on the plate.
As far as figuring out if the dog's mouth bacteria is harmful, you would have to use the gram stain to determine this. I, unfortunately, don't know of a better way to test for this, and with parent help and understanding of how to carry it out, it should be simple. I advise buying a gram-staining kit online, as there are a few components to the procedures.
Also, if this looks like too much or if it's too much of a hassle, you would be fine only looking at the quantity of bacteria as you mentioned before and exclude the gram-positive/negative aspect.
Here is some background information that your scientist would have to include in his science fair write up:
https://www.austincc.edu/microbugz/gram_stain.php
Here are the procedures for gram staining:
1. Smear a colony onto a microscope slide
2. Allow the slide to completely dry so no bacteria falls off when staining.
3. Saturate the smear with crystal violet for 1 minute.
3. Rinse the slide gently with water until the water dripping off is clear.
4. Saturate the smear with iodine for 1 minute.
5. Rinse the slide gently with water until the water dripping off is clear.
6. Decolorize with Gram decolorizer (acetone/alcohol) for 3-5 seconds ONLY; if you leave the
decolorizer on too long, it will bleach the crystal violet out of a gram-positive cell!
7. Rinse the slide gently with water.
8. Counterstain with safranin for 1 minute.
9. Rinse the slide gently with water until water becomes clear
10. Place a coverslip over your sample so the microscope isn't damaged.
11. Observe the slide under the microscope, using proper microscope technique.
With proper staining technique…
Gram positive bacteria will stain purple.
Gram negative bacteria will stain red/pink.
Here's the link to buy a kit:
https://www.amazon.com/Innovating-Scien ... 272&sr=8-4
Happy Staining! Post again if you have any more questions or would like something clarified.
lmp1341