We were successful in enriching and isolating a species of Pseudomonas.  We collected soil samples from around University of Maryland's campus as well as from a garden in Silver Spring for enrichment and isolation. After 48 hour of incubation, all broth samples appeared to be a yellow/brown and opaque, thus indicating positive growth.  To further isolate and enrich for a Pseudomonas we were successful in obtaining a pure culture in Pseudomonas  All plates, regardless of the reservoir, showed growth of colonies similar in appearance:  small, round, smooth, and beige in color.
 
        To confirm our successful isolation of a Pseudomonas species, we conducted Gram stain, wet mount, catalase, and oxidase tests.  Gram stain results showed pink, straight rods confirming that the cells were Gram negative.  Motility was observed in wet mounts which were consistent with the characteristics of Pseudomonas .  Furthermore, the emission of bubbles in the catalase test showed that the cells were able to metabolize toxic by-products of aerobic respiration.  Lastly, the oxidase test was positive as the cells turned blue with the addition of  p -phenylenediamine.

        Pseudomonas are known to be Gram negative straight or curved rods with polar flagella that are always catalase positive and could be either oxidase positive or negative.  Therefore based on our test results, we have a positive identification of Pseudomonas.

        Pseudomonas has been used to clean up oil spills and degrade pesticides around the world.  We wanted to reproduce this in our experiment after successful isolation a Pseudomonas species .  To test our hypothesis, we simulated an environment where oil was the sole carbon source.  This was done by eliminating peptone from a minimal nutrient agar and replacing it with Exxon Classic motor oil.  In addition phosphorus and nitrate was included in the agar to boost bacterial growth and thus the rate of oil degradation.  After incubating the pure Pseudomonas on these oil plates for 96 hours, growth was still not observed.

        Growth might not have occurred for several reasons.  Research has shown that oil metabolism by Pseudomonas is slow process.  If the incubation period was extended, growth may have been observed.  Secondly, the Pseudomonas species that was isolated in our experiment may not have necessarily been the species capable of degrading oil.  Furthermore, we may have used an excessive amount of oil which could have prevented the cells from having access to the nutrient agar while suspended on the oil surface.  For future experiments, oil broth may prove to be more successful.