Date of Award
Doctor of Philosophy (PhD)
A new method for the continuous measurement of low rates of oxygen production is described, which is useful for the study of photosynthetic systems. An inert carrier gas flows at a controlled rate through a cuvette, then over a solution of luminol and potassium t-butoxide in dimethylsulfoxide (DMSO). The light generated by the chemiluminescent reaction of luminol with oxygen is measured with a photomultiplier. A constant rate of oxygen production by photosynthesis in the cuvette is seen as a constant displacement from a steady baseline. The baseline is caused by the oxygen impurity in the carrier gas. Electrolysis of water is a convenient method for the calibration of the luminometer. The response of the luminometer is linear with oxygen concentration over at least six orders of magnitude, and changes of 0.01 ppm or 5 x 10-14 moles/sec. in rate of generation of oxygen are detectable when the carrier gas contains 1 ppm oxygen impurity. The system has a response time of about 3 minutes, and a precision of better than 5%. Various mutants of Chlorella having a variety of abnormal pigments were screened for their photosynthetic activity. Some mutants could make oxygen photosynthetically though they were discolored by abnormal quantities of chlorophyll precursors and had only about 1% of the normal chlorophyllJconcentrations. Mutant 610, a carotenoid-containing mutant which, unlike normal Chlorella, cannot synthesize chlorophyll in the dark, was found to green in the lighto During greening, the synthesis of chlorophyll and the development of the ability to produce oxygen were shown to be independent of cell division. On the other hand, during degreening in the dark, the loss of chlorophyll and photosynthetic ability was shown to be dependent on cell division. The luminometer was found to be capable of measuring the light-saturation curve of Chlorella at light intensities down to at least three orders of magnitude below the half saturation intensity. Other possible ways of using the luminol detection method are discussed, and some advantages of mutant 610 for the study of greening are prop
Burr, Arthur H. Jr, "The Luminometer: A Sensitive Instrument for Measuring Low Amounts of Oxygen and some Applications to Problems Involving the Measurement of Photosynthesis" (1966). Student Theses and Dissertations. 573.