Biology ETDs

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The growth of Desulfovibrio vulgaris and D. gigas on various electron donors and electron acceptors was measured in order to determine the influence of the donors and acceptors on energetics of growth. When using lactate, pyruvate, or formate as electron donors, and sulfate, sulfite, thiosulfate, or fumarate as electron acceptors, pyruvate-sulfate medium produced the most rapid growth, and intermediate levels of growth were observed on lactate­sulfate, with lowest levels on formate-sulfate. Both organisms grew best when sulfate was the electron acceptor regardless of electron donor. No growth occurred in cultures containing pyruvate and sulfite, and slight growth was observed in all cultures using fumarate as the electron acceptor. Molar growth yields were determined for growth of D. vulgaris and D. gigas on lactate and pyruvate medium, with sulfate as the electron acceptor. The results of these determinations suggest that two oxidative phosphorylations are coupled to the transport of electrons from lactate or pyruvate in D. vulgaris, while one oxidative phosphorylation would appear to occur with the oxidation of lactate or pyruvate by D. gigas. Levels of pyruvate dehydrogenase, thiosulfate and bisulfite reductases, and c-type cytochromes were measured in cultures of D. vulgaris at several stages of growth on lactate or pyruvate medium with sulfate as the electron acceptor. The levels of thiosulfate reductase were 2.5 times greater, and bisulfite reductase activity 3.3 times greater in cells grown on pyruvate-sulfate, when compared to those grown on lactate-sulfate, while c-type cyto­chromes and pyruvate dehydrogenase levels were 1.3 and 1.7 times greater, respectively, in cells grown on pyruvate-sulfate medium. Examination of pyruvate dehydro­genase activity in cell-free extracts from D. vulgaris grown on lactate and sulfate medium revealed that evolution of carbon dioxide from pyruvate is strongly inhibited by the addition of sulfite to the reaction mixture.



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Department Name

UNM Biology Department

First Committee Member (Chair)

Larry Barton

Second Committee Member

Paul R. Kerkof

Third Committee Member

David L. Vander Jagt

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Biology Commons