Browsing by Subject "phototrophic sulfur bacteria"

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    Developing a microfluidic device for in situ water column profiling of phototrophic sulfur bacteria
    (Office of the Vice Chancellor for Research, 2015-04-17) Kellogg, Austin; East, Zachary
    Phototrophic purple sulfur bacteria are crucial to study in Biogeochemistry because they are thought to be one of the first organisms to utilize photosynthesis. In the early atmosphere, there was very little oxygen present. Sulfur bacteria use light and sulfides as energy in anoxic conditions. Conditions suitable for sulfur bacteria can be found in anoxic lakes, which many are located in northern Indiana and the Pacific Northwest. The main goal of this project was to design and create a device that could record data and abstract samples of purple sulfur bacteria in anoxic lakes. In order to create this device, we first had to test the purple sulfur bacteria’s light absorbance using a spectrophotometer. The data collected about the sulfur bacteria’s absorbance was used by us to optimize our design for the circuit which incorporated the LED and Photo-detector components. Also, a Thermosensor component was added in an attempt to determine the optimal temperature sulfur bacteria lives in. Overall, six Op-amps were used in order to limit the amount of noise and to convert current into voltage so temperature and light absorbance can be measured.
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    Fluorescence Measurements Of Phototrophic Sulfur Bacteria For Applications In Water Column Profiling
    (Office of the Vice Chancellor for Research, 2015-04-17) Gurdasani, Simran S.; Harper, Lynsie A.; Petrache, Horia I.; Ray, Bruce D.; Gilhooly, William P., III; Johnson, Merrell A.
    Unlike plants that produce oxygen during photosynthesis, phototrophic sulfur bacteria use sulfide and sunlight to produce carbohydrates and elemental sulfur. These bacteria require a unique aquatic environment to thrive: one that is anoxic (depleted of oxygen) and rich in hydrogen sulfide. Such conditions are found in a number of stratified lakes around the world including several in Northern Indiana. Studying the ecology and geochemical conditions that promote habitable conditions for phototrophic bacteria in lakes provides insight into the Early Earth (thought to be anoxic), ocean anoxic events of the Mesozoic (70-250 million years ago) and modern low oxygen conditions of coastal environments such as the Dead Zone of the Gulf of Mexico. However, locating and directly sampling these bacterial populations in vast bodies of water is not an easy task. In this project, we investigate fluorescent properties of purple sulfur bacteria in order to develop a dependable sensor that can be deployed in the water column. We report a number of measurements of purple sulfur bacterium fluorescence in the near infrared region when excited at discrete wavelengths in the UV range. We use these bench-top measurements to design a water-proof apparatus equipped with an absorption and luminescent detector for localization of bacteria in lake water. This device will be deployed in anoxic lakes of Northern Indiana to find the in situ water column position of phototrophic bacteria.