Results

Bioreactor

Initial Bioreactors

Conclusion:

          Because the graphs of temperature, dissolved oxygen, and carbon dioxide were similar between the two sized bioreactors (2 L and 20 oz), the smaller size was chosen to be used for testing temperature environments for efficiency.

Warm Bioreactors

Conclusion:

          The rate of carbon dioxide production and dissolved oxygen intake increased and then level off by 25 minutes. This reaction occurred too quickly for ideal conditions of a bioreactor.

Cold Bioreactors

Conclusion:

          The rate of carbon dioxide production increased much more slowly than the warm reactors and then decreased after 50 minutes, indicating a slow metabolism and finally a decrease in metabolism. The dissolved oxygen increases unlike the warm reactors, and then slowly decreases as the bacteria use the oxygen. The bacteria, however, use it more slowly than the warm reactors and level off at a higher rate of dissolved oxygen.

Bacteria

Optical Density

Conclusion:
          Though there was inconsistency, the typical value of the control plates was higher than that of the toluene plate. A higher absorbance reading means that there was more bacteria growth. This indicates that because of the addition of toluene, there was less bacteria growth.

Gram Stain

Conclusion:
          Because P. putida is a gram negative bacteria, the predicted result was pink rods. However, due to a possible contamination of the materials for the procedure, the results between gram negative and gram positive were inconclusive. However, the test confirmed that the bacteria were rod-shaped.

Folin's Reagent

Conclusion:

          The data proves inconclusive because of the great dissimilarity between the absorbance values for each trial accounting for the lack of precision. These values were expected to be close because each trial followed the same procedure and used the same materials as the next. This can be attributed to many errors, including those made by the individual such as not properly following the procedure. An abnormally high value in absorbance could be the result of a dirty cuvette since it would absorb more of the light than the clean cuvette. A high value could also be caused by an increased density of bacteria for the same reason of more absorption of light. A significantly lower value in absorbance could be the result of a too low level of liquid in the cuvette so that no or little light would be absorbed. Lastly, a low absorbance could be accounted for by an error in extracting the nutrient broth from the test tubes. If extracted incorrectly, toluene, which does not contain the stained hydrocarbons, could be present in the solution placed in the spectrophotometer.

          In order to prevent these errors from occurring in the future, there should be a uniformity in the cuvettes, in size and cleanliness, to prevent a difference in absorbance readings. Also, all sample should be filtered, mixed, or centrifuged before being placed in the spectrophotometer in order to remove the possibility of bacteria interfering with the reading. Finally, the containers used when extracting the nutrient broth should be easily accessible by the pipettes, in order to prevent toluene from being mixed with the nutrient broth.