Publication Date


Document Type


First Advisor

Meganathan, Rangaswamy

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences




D-cycloserine (DCS) is a naturally occurring broad-spectrum antibiotic produced by Streptomyces orchidaceus. It is a structural analog of D-alanine and it is used for the treatment of antibiotic resistant Mycobacterium tuberculosis in conjunction with other first line drugs like isoniazid and rifampin. It inhibits the synthesis of the cell wall by inhibiting the enzymes alanine racemase and D-alanyl-D-alanine ligase. In previous studies, three DCS resistant Escherichia coli mutants were isolated by Curtiss et al (1965). Wargel et al (1971). identified in these mutants that cycA is responsible for the transport of DCS. Later, a study by Baisa et al (2013) reported that cycA is responsible for the transport of DCS only when grown in minimal media but not in complex media. They also further stated that a fully functioning respiratory chain is required for sensitivity to DCS. Ubiquinone mutants, ubiE, ubiF, ubiG, ubiH and ubiX, were reported resistant to DCS in complex media. In this study, we tested the wild type and ubiquinone mutants, (DeltaubiB, DeltaubiD, DeltaubiE, DeltaubiF, DeltaubiG, DeltaubiH, DeltaubiH Operon, DeltaubiX, and DeltaubiI) in different media and under aerobic and anaerobic conditions. Our studies showed that certain mutants were sensitive to DCS under aerobic and anaerobic conditions in complex media, whereas all the mutants were sensitive to DCS in aerobic and anaerobic conditions in minimal media with glucose or glycerol as carbon sources. Further with the oxidizable carbon source glycerol and fumarate or nitrate as electron acceptor, all the mutants were sensitive.


Advisors: Rangaswamy Meganathan.||Committee members: Yanbin Yin; Shengde Zhou.||Includes illustrations.||Includes bibliographical references.


38 pages




Northern Illinois University

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