Dental Bacteria Growth Experiement

[deleted-742125]

Hi,

I am working on a syllabus for a new 8th grade microbiology and epidemiology elective course. I was given a nice idea by a colleague, but I am having trouble working out the details. The suggestion I received was to have students swab their teeth and grow cultures on regular nutrient agar and sucrose agar. The bacteria would grow better and produce dextran on the plates with sucrose. (According to my colleague)

Here are my questions:
1) Do I add sucrose to purchased bottled nutrient agar before microwaving it to melt / sterilize it and pour plates? I have seen a few references that a concentration of 5% by weight is a good amount of sucrose to have. If not, I am having trouble finding a prepared sucrose agar.

2) What's dextran and how do I know if the bacteria have produced it? Can I quantify results?

I would like to use this general set up to provide students with an opportunity to look at how dental hygiene practices impact bacteria presence in their mouth in student developed investigations. I just want to make sure that I am providing them with a system that works. The investigations would coincide with research into the connection between oral hygiene and heart health and cognitive health, in addition to oral health.

Thank you for any insight you can provide!

[DrSullivan]

1. It looks like you can autoclave the sucrose with the agar, so you should be able to add it before microwaving.
2. This link may help define dextran. As for measuring it, you may need to buy an anti-dextran fluorophore and use a spectrophotometer.

Hope this helps.