Oil Be Seeing You

Purpose- To determine the relationship between soil environments and the activity of petroleum-degrading bacteria.

Background information-Petroleum is a rich source of organic matter.  It is not surprising, therefore, that a wide variety of microorganisms will readily attack it under certain environmental conditions.  This demonstrates a beneficial role of microorganisms- the biodegradation of pollutants.  Significant breakdown will only take place in the presence of oxygen.  If the oil is deposited into an anaerobic environment (absence of oxygen), decomposition will not occur and it may remain in place for many years.  This helps to explain why natural oil deposits may be millions of years old. The physical properties of oil, which are insolubility in water and low density, will explain the formation of oil slicks.  The oil is exposed to oxygen and is quickly attacked by oil-degrading bacteria, which eventually decompose the oil and disperse it.  Petroleum degraders include a variety of  bacteria, certain molds and yeasts.  Most soil should have bacteria, capable of using oil.  Service stations most often have oil-soaked soil, which is an excellent source of these microorganisms.  Oil-degrading bacteria often use other common organic chemicals, such as moth balls, as nutrients.

Materials
5-clear, covered experimental containers (125ml minimum)
5- volume-measuring containers
4- 10 ml. Pipettes and pipette pumps
4 collection bottles
Clear metric ruler
Distilled water
Moth balls
30 ml. Nutrient broth, Miracle-gro or dissolved chicken bouillon cube
Rubber gloves
Lysol or 10% bleach solution
Paper towels

Procedure for Detecting the Presence of Oil-degrading Bacteria

Field Activity

1. Collect soil samples from four different locations.  Look for areas that vary in their exposure to oil.  (Examples include soil near a gas station and from a garden.)
2. Label and date each collection bottle.

1. Prepare an aseptic work area.
2. Prepare experimental and control specimens, using clean experimental containers.
3. Add 50 ml. Distilled water to each container.  Close each container with a cover.
4. Using a pipette, measure 5 ml of nutrient solution.   Add it to the first container and replace the cover.  Repeat for each of the remaining four containers.  Replace covers.
5. Add a 10 ml soil sample to the container with the matching label.  Replace covers.  Gently swirl each covered container.
6. Ask your teacher to place the moth ball in each container and replace covers..
7. Incubate at room temperature in a space designated by the teacher for a minimum of seven days.
8. Without removing the moth ball, measure the vertical and horizontal axes of each moth ball, once a day for seven class days.

1. Report is to be written in standard lab report form.

1. Describe any non-quantifiable observations that occurred in the specimens.
2. Describe another sampling technique that could be used to test for oil-degrading bacteria.
3. Describe any sources of error that may have affected the results.
4. Compare data with at least three other groups.  Describe and explain any similarities and differences you have observed.

1. Survey local service stations to determine their methods of oil disposal.
2. Take a field trip to an oil refinery.
3. Do an internet search on applications of bioremediation.
4. Isolate and identify microbes from cultures.  (Advanced)