Science Buddies: "Ask an Expert"

I am conducting an experiment on bioremediation of petroleum contaminated soil using microorganisms. I am planning on using fungi and bacteria as the microorganisms. I was wondering how much of each microorganism should be added to every 500 ml of contaminated soil.

Hi,

It would be impossible to answer your question without knowing WHICH bacteria and fungi you plan to use, and whether you plan to use them separately or together. Bacteria vary considerably in their capability of degrading petroleum, so the species used is critical.

Also, when you say ‘contaminated soil’, how much and what kind of oil are you ‘contaminating’ it with? The more oil that is in the soil, the more microbes that would have to be added to degrade it.

Take a little time and explain the purpose of your project, what your hypothesis is and what you will be measuring and then maybe we can answer your question. It is likely that you will have to do a test run first by adding different numbers of bacteria to contaminated soil and measuring how much oil they can degrade. The number of bacteria per 500 ml of soil should be one of your independent variables. Time is another important variable in remediation. How long will it take the bacteria and/or fungi to break down a certain amount of oil?

It sounds like a good project but we can’t help you if you don’t give us the details.

Sybee

Hello there,

Really cool project idea! I completely agree with what SciB had said above. It would be helpful for us if you could provide a little more details about your project, your main question, your hypothesis, and how you're going about testing it so we can give you the most constructive advice as possible. Which bacterial and fungal species do you have in mind for your experiments? Are they known to degrade oils, or are you testing species where it is unknown that they can degrade oils to see if you can discover novel oil-degrading functions for these microbes? I think it would be cool to test the oil-degrading ability of your bacterial species and fungal species separately, and then see if putting the bacteria and fungi together will make oil degradation even more efficient. This I think will be important to test because many fungi are known to produce antibacterial compounds, and if your bacterial and fungal species happen to antagonize each other, then putting them together to degrade the same "contaminated soil" sample may not be efficient at all. Just some questions to think about.

Let us know if you have anymore questions, and post back with more details about your project if you still need help!

Connie