Re: How can I measure the percentage of crude oil eaten by oil eating microbes?

hi Jessica,

Interesting project! It will certainly be challenging. Some of the problems that you will need to solve are:

• Finding a source of bacteria. Do you want to use a "pure culture" or an environmental sample? If a pure culture, you'll need to obtain it from a culture collection and know how to grow and maintain it aseptically. For this experiment an environmental sample might be more interesting - soil, water from a lake, maybe taken from a place where you know that there is oil contamination.
• Growing your bacteria. They can't live on just oil - they need other nutrients too and if you want results quickly, they should grow quickly - so they should probably be kept warm.
• As you point out - measuring the amount of oil and bacteria. If bacteria grow fast enough they will make a solution cloudy - that could be a way to monitor them. And if you can concentrate your oil into a solid form, perhaps you could measure changes in the size of an oil sample?

I did a bit of "Googling" and it turns out that other people have also thought about your problems. Try some of these links:

Oil be seeing you. These people used moth balls in their project. Moth balls contain a lot of napthalene, which is a petroleum product made from oil, so they were looking at napthalene degradation. There are more details at this link.

Oil spill in a test tube. This is a bit more sophisticated - it requires bacterial culture and a piece of lab equipment called a spectrophotometer to measure the cloudiness (turbidity) of a solution, but it might give you some ideas.

A student's experiment sounds very similar to what you want to do. I'm not suggesting that you steal his work or that it's the same as your idea, but again perhaps it will give you some ideas!

Nebraska Scientific Company sells an oil-degrading microbe kit, if you have $98.50 to spend :)

Here's another link on oil degradation - a lab for high school students.

Hopefully you'll find some ideas in there - I used the search term "oil degrading bacteria student lab" at Google and got lots of hits, so try that too. Google is your friend!