Science Buddies: "Ask an Expert"

Hello,
Im testing two natural agents, one an essential oil and the other a sugar alcohol, then both mixed together, to see if the bacteria in the mouth that I grew, Streptococcus Mutans will be effected by greater concentrations.

Questions:
1- Is the zone of inhibition where the bacteria died? Does the ZOI change over time?
2- Is saying inhibit bacterial growth with the paper disks filled with the two natural agents on the incubated petri dishes of Strep Mutans correct or can I say colony death? Trying to use correct terminology inhibit is death of colony partially?
3- Can the xylitol and cinnamon leaf oil be differ concentrations then each other?

Hi somofrietti,

To answer your questions:
1) Yes. It changes only if the antimicrobial agent leaks out/spreads.
2) Yes, say "inhibit growth" rather than death.
3) No, you should use same concentrations. You can produce a dose response curve where you treat with a range of concentrations.

Here's a little bit more about the subject -> http://microchemlab.com/test/zone-inhib ... l-activity

Peter S.