Publication Date


Document Type


First Advisor

Meganathan, Rangaswamy

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Bacterial growth; Methionine sulfoxide; Escherichia coli


Escherichia coli grew anaerobically in a complex medium with glycerol as the carbon source and methionine sulfoxide (MetSO) as the terminal electron acceptor. MetSO reductase activity, measured with NADPH as the electron donor, was present only when the particulate and supernatant fractions of extract preparations were present. NADH and sodium dithionite could also serve as electron donors for MetSO reduction. MetSO reductase activity was shown to be constitutive and not repressed by oxygen. Mutants of E^ coli blocked in the biosynthesis of menaquinone (men) were unable to use MetSO as an electron acceptor to glycerol complex media. Growth of men mutants could be restored by the addition of menaquinone intermediates in the medium. MetSO reductase activity in extracts of men mutants was absent unless cells used to prepare extracts were grown in the presence of menaquinone precursors. The requirement of a molybdenum cofactor in MetSO reduction was shown by the inability of chi mutants, known to be defective in molybdenum processing, to grow in glycerol plus MetSO media. It is known that anaerobic growth of chlD mutants with nitrate as the electron acceptor can be restored by high concentrations (10 mM) of molybdate. Growth of the chlD mutant in glycerol MetSO media could be restored by high concentrations of molybdate, reductase activity in extracts of chi mutants was but activity in extracts of the chlD mutant could MetSO absent be restored by growth of the cells in 10 mM molybdate.


Bibliography: pages [46]-48.


48 pages




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