Hi,
The bacterium I was talking about,
A. borkumensis, is a marine bacterium used to clean up oil spills in the ocean which are much more likely to occur than oil spills in fresh water. But if you have to do your experiments on fresh water then I would suggest using
Bacillus subtilis. This bacterium will grow in water supplemented with a specific mineral salts mixture containing the following amounts per L: K2HPO4, 3 g; KH2PO4, 1 g; NH4Cl, 0.5 g; NH4NO3, 0.1 g; Na2SO4, 0.1 g; MgSO4-7H20, 10 mg; MnSO4*4H20, 1 mg; FeSO4.7H20, 1 mg; CaCl2, 0.5 mg; pH adjusted to 6.8-7.0.
You can buy
B. subtilis from Carolina Bio:
http://www.carolina.com/catalog/search- ... SearchForm
Normally when
B. subtilis is grown in liquid culture glucose is added as the carbon source, but if you add oil instead, such as mineral oil, the bacteria should use that and grow. The better the bacteria use the oil the faster they will grow. You could test the effect of reducing the salts in the medium to one-tenth of their optimal concentration on the degradation of oil. You don’t need to measure the oil itself, just count the bacteria after incubating them for a few hours with the oil. The greater the number of bacteria, the more oil was degraded.
Bacterial counts are usually done by making serial dilutions of a culture, plating them on agar in a Petri dish, incubating them for 24-48 hours at 21-30C and counting the resulting colonies. If you have never done this before here’s a youtube video that shows how it’s done. You can buy the agar plates from Carolina Bio.
Here’s a good website that defines what it means for bacteria to ‘clean up’ oil and explains the various ways that different bacteria digest crude oil:
http://www.dfo-mpo.gc.ca/science/public ... x-eng.html
Here’s a paper that lists the various bacteria that can degrade oil:
http://www.hindawi.com/journals/btri/2011/941810/
Nine bacterial strains, namely,
Pseudomonas fluorescens, P. aeruginosa, Bacillus subtilis, Bacillus sp.,
Alcaligenes sp.,
Acinetobacter lwoffi,
Flavobacterium sp.,
Micrococcus roseus, and
Corynebacterium sp. were isolated from the polluted stream which could degrade crude oil.
Here’s a quote from the paper talking about the effects of nutrients on the ability of bacteria to degrade oil:
“Nutrients are very important ingredients for successful biodegradation of hydrocarbon pollutants especially nitrogen, phosphorus, and in some cases iron [34].
Some of these nutrients could become limiting factors thus affecting the biodegradation processes. Atlas [35] reported that when a major oil spill occurred in marine and freshwater environments, the supply of carbon was significantly increased and the availability of nitrogen and phosphorus generally became the limiting factor for oil degradation.”
“The most rapid and complete degradation of the majority of organic pollutants is brought about under
aerobic conditions.” In other words, the bacteria need oxygen to digest the oil and grow.
If you need more information for your experiments please let us know. It would be helpful to the experts if you would briefly state your hypothesis and outline the experiments you plan to do to test it.
Good luck!
Sybee