Browsing by Author "Johnson, Ewan Douglas"

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    Bioorganic studies in Streptomyces species: Engineering the development of bioactive compounds
    (2001) Johnson, Ewan Douglas; Billups, W. Edward
    With the proliferation of multiresistent bacteria in clinical settings and the realization that these bacteria are even resistant to vancomycin. Efforts are currently underway to integrate both biosynthetic and genetic engineering techniques that promote the development of bioactive compounds elaborated by Streptomyces bacteria. The gram positive bacteria of the genus Streptomyces are well documented as having the ability to elaborate a wide range of structurally diverse compounds that have demonstrated varied bioactive properties. The research efforts in this dissertation conducted studies utilizing C-13 stable isotopes to elucidate the origins of C1', C2', C5' and C6' of octosyl acid A and polyoxin D, compounds elaborated in the fermentation broth of Streptomyces cacaoi var. asoensis. Protocols were developed for the genetic manipulation of Streptomyces threomyceticus and Streptomyces cacaoi var. asoensis. Genetic and molecular biology techniques were optimized to promote the conjugation and subsequent transfer of genetic material from gram negative Escherichia coli (S17-1) bacteria to the chromosome of gram positive bacteria Streptomyces threomyceticus. In addition, techniques were developed for the conjugation of S. cacaoi . var. asoensis. with E. coli. In this study, biosynthetic investigations demonstrated that the origin of 6' carbon of octosyl acid A and polyoxin D was pyruvate. It is postulated that pyruvate is converted to phosphoenolpyruvate before condensing with an analog of uridine aldehyde. Furthermore C-1' , C-2' and C-5' of the ribose moeity were derived from pyruvate after it was cycled through the pentose phosphate pathway. Application of directed biosynthesis to induce the production of new compounds resulted in the formation of a number of bioactive compounds. In this study, 5-hydroxymethylfurfural was identified, isolated and fully characterized. This compound, along with polyoxin D, was also shown to inhibit the growth of the test phytopathogenic fungus Cochliobolus miyabeanus.