Classified as a chemoheterotroph, Pseudomonas are found in a variety of environment including soil, plants, fresh and sea water, and sewage.  They can process a diverse range of chemicals including pesticides and oil. Furthermore, they are able to survive harsh conditions in which other microorganisms cannot.  For instance, Pseudomonas is capable of living in antiseptics and soap residues.

        Because of it's ability of degrade oil, Pseudomonas has been used to clean up oil spills around the world.  Although this is a slow process, nitrogen and phosphorous have been found to accelerate the growth of Pseudomonas.

        Bacteria from the genus Pseudomonas are mesophiles and live best at a neutral pH.  For this reason, we allowed our enrichment broth and agar to be incubated at 25^oC.  Since they are obligate aerobes, we grew them in an environment where oxygen was present.  Potassium nitrate was used in the broth and oil agar to serve as an electron acceptor to maintain anoxic conditions.  To inhibit the growth of fermentative bacteria, a non-fermentable energy source, benzoate, was used as an electron donor in the enrichment broth.  A denitrifying bacteria, Pseudomonas can grow in the presence of cetyl trimethyl ammonium bromide, a toxic compound for most other organisms.  We therefore used this substrate in the isolation agar to inhibit growth of other bacteria.  Because they are not photosynthetic, by incubating isolation agar in the dark, photosynthetic bacteria were inhibited while Pseudomonas was allowed to grow.  In order to expedite the oil metabolism process, potassium nitrate was added to the oil agar.

We hypothesize that degradation of oil on agar plates will occur using a pure Pseudomonas culture isolated from a soil sample.