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Caslin Gilroy Dr. Lewis Semprini Environmental Engineering

Correlation of NE 1545 Expression and Cell Size in Nitrosomonas europaea Exposed to Aromatic Hydrocarbons. Caslin Gilroy Dr. Lewis Semprini Environmental Engineering. Wastewater Treatment Plant. N. europaea.

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Caslin Gilroy Dr. Lewis Semprini Environmental Engineering

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  1. Correlation of NE 1545 Expression and Cell Size in Nitrosomonas europaea Exposed to Aromatic Hydrocarbons Caslin Gilroy Dr. Lewis Semprini Environmental Engineering

  2. Wastewater Treatment Plant N. europaea

  3. The process of nitrification exhibited by N. europaea is represented by the following reactions: 2H+ + 2e- + NH3 + O2 NH2OH + H2O This step is catalyzed by the enzyme AMO H2O + NH2OH  NO2- + 5H+ + 4e- This step is catalyzed by the enzyme HAO Notice that there is a net gain of two electrons, which are used by the bacteria for energy

  4. Why is this bacterium important? N. europaea prevents eutrophication in wastewater treatment plants.

  5. Causes of Inhibition in Ammonia Oxidation • N. europaea is very sensitive to common inhibitors (CN, heavy metals, pH shifts, and organics). • Currently can monitor chemical inhibition, but cannot determine cause. • Therefore cannot neutralize inhibitors and wastewater treatment plant failure can occur.

  6. Solution • Want to be able to detect nitrification inhibition AND determine cause of inhibition. • Do this by identifying genes expressed in response to specific inhibitors. • Create a biosensor to detect N. europaea’s gene expression and link expression to specific chemical contamination.

  7. Shift in Cell Membrane Structure Control 40 mM Benzene Membrane thickness decreased from 103 + 11 nm to 71 + 4 nm

  8. Possible Biosensor Gene Identified • NE 1545 linked to cell membrane size and organic compound exposure. • Hypotheses: • Increased expression of NE 1545 is correlated with exposure to certain aromatic hydrocarbons. • Exposure to these hydrocarbons is correlated with a decrease in membrane thickness.

  9. Batch Experiments

  10. Nitrite Assay

  11. Membrane Stability 1 2 3 4 5 6 7 8

  12. Membrane Stability 1 2 3 4 5 6 7 8 9 10

  13. Future Study • Continued experimentation with NE 1545 to determine if it is an effective sentinel gene for our biosensor.

  14. Acknowledgements • Howard Hughes Medical Institute • Dr. Lewis Semprini • Dr. Tyler Radniecki • Dr. Kevin Ahern

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