I'm not much of a Bio guy, but I came across this on wiki: "Acetobacter can be easily distinguished in the laboratory by their growth of colonies on a medium containing about 7% ethanol, and enough calcium carbonate to render the medium partially opaque. When Acetobacter colonies form enough acetic acid from the ethanol, the calcium carbonate around the colonies dissolves, forming a very distinct clear zone."
That experiment sounds easy enough to rig up at home. I'm thinking diluting vodka to 7%, adding some calcium carbonate, and I guess sugar? Any ideas how much of those I should add?
If the gravity is dropping, does that mean that the sugars are being consumed? Acid is denser than ethanol, right? So if the bug were eating ethanol and making acid, the gravity would go up? Do acetobacter eat sugar?