I realise that the best way to prove the existence of germs or single-celled org
ID: 36853 • Letter: I
Question
I realise that the best way to prove the existence of germs or single-celled organisms is by looking at them through a microscope. But I don't have a microscope at my home, how can I design an experiment in a normal house environment to show the existence of germs (or other single-celled organisms) without spending too much money?
By "house environment" I mean that I have access to normal stores and the internet. If it's something that can be bought in a "normal" store or on-line without getting me into trouble, and doesn't cost a lot then I can have access to it. I don't have access to lab grade equipment or conditions, so no sterile rooms or special growth environment.
I thought about the following experiment, inspired by the mythbusters pyramid power episode. In the episode they cut an apple in half and put one half under a pyramid and the other not under a pyramid. In the first attempt one of the halfs rotted quicker than the other, they concluded that it happened because the saw they used to cut the apples wasn't sterile.
So I thought about taking 3 apples, contaminating a knife (by rubbing human saliva on it). Cutting one apple with the contaminated knife, one apple with a sterile knife (using rubbing alcohol to sterilize it) and one apple by a knife that has 1 contaminated side and one sterile, which is a contaminated knife, that had only 1 side sterilized with rubbing alcohol. Then leaving the 6 halves in separated sealed containers (some tupperware) for a few days and then looking examining the rott. The expected result is that the "contaminated apple" will have a lot of rot on both halves, the "sterile" apple will have no (or close to no) rot, and the half and half apple will have one rotten side and one not rotten side, and the sides will coincide to the contaminated/sterile sides of the knife touching them.
Will this experiment work?
Explanation / Answer
You could use Jell-O for growing bacteria if you don't have access to agar ! (I have never tried this but I think it should be possible because the gelatin in Jell-O is like agar.)
You should first sterilize a small knife on a gas stove or with alcohol and then gently rub it on any surface (where you think bacteria are likely to be found ) and then rub it on Jell-O taken in a dish. You should then place it in an environment similar to the one from where you isolated the bacteria. After one or 2 days the bacteria should grow.
For control : You could simply put a plate of Jell-O in the same place but without inoculation of bacteria.
Disclaimer : I am not a microbiologist and I am not sure this would work but you could give it a try as it will not be really expensive :)