No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 57-64).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Part I, A-B reprinted from the Journal of the American Chemical Society, v. 70, 1948 ; Part I, C and part II typewritten. Vita. Includes bibliographical references (leaves 10, 34).

The effect of dihydrostreptomycin on the growth and induction of the enzyme, penicillinase, in Bacillus cereus has been studied. Two B. cereus variants were used: a sensitive culture, the growth of which was arrested by approximately 0.3 units of dihydrostreptomycin per milliliter of medium; and a resistant type which would grow in the presence of 2,000 units per milliliter of dihydrostreptomycin. This resistant strain was developed from the parent sensitive organism by successive transferring and plating techniques. The enzyme, penicillinase, was induced with penicillin and assayed manometrically. In the antibiotic-sensitive B. cereus, it was found that the formation of penicillinase, and not penicillinase action, was inhibited by dihydrostreptomycin. Further, total inhibition of penicillinase induction occurred with a concentration of antibiotic that inhibited growth of the organism. This inhibition of penicillinase formation was found to fit the mass law equation, xy = C, where x is the dihydrostreptomycin concentration, y is the fractional enzyme synthesis, and C is a constant. In the antibiotic-resistant B. cereus, neither growth nor penicillinase formation was inhibited by much higher concentrations of dihydrostreptomycin. A slight "partial dependence" on the antibiotic was noted. When antibiotic-resistant cultures, which had been grown in the absence of dihydrostreptomycin, were induced with penicillin in the absence and in the presence of streptomycin, there was, in the absence of the antibiotic, a longer lag period for the formation of penicillinase. That is, the resistant organism showed a slight dependence on streptomycin in the early stages of growth and enzyme induction. It was found that short periods of sonic treatment of suspensions of B. cereus produced an increase in the rate of penicillinase induction. Longer periods of sonic treatment, however, decreased the rate of enzyme induction. The results of this study - that streptomycin inhibits the formation of penicillinase in sensitive B. cereus but does not inhibit the action of this enzyme -were speculatively correlated with the known synergism between streptomycin and penicillin. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

No description available.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The problem of finding an efficient antibiotic against Pseudomonas aeruginosa which can be used in the clinical treatment of genito-urinary tract infections resistant to treatment by streptomycin has not yet been solved. Therefore, this problem has consisted of first, the acquisition of possible inhibitors of the streptomycin resistant strain of Pseudomonas aeruginosa; second, the selection and identification of those which show a marked antagonism toward this organism; third, the determination of the antibiotic spectra of the inhibitors; fourth, the determination of whether the streptomycin resistant strain could also acquire a resistance to the antibiotic produced by its inhibitors; and last, an attempt to evaluate the therapeutic possibilities of the antibiotics demonstrated.

Streptomycin resistance in E. coli ribosomes is conferred by alterations in the amino acid sequence of 30S ribosomal protein S12. The alterations result from point mutations at specific locations in the rps12 gene. A point mutation at a conserved nucleotide in the 16S rRNA gene, originally identified in Euglena gracilis chloroplasts, also confers streptomycin resistance to prokaryotic-like ribosomes. The Nicotiana tabacum mutant "SR1" possesses a chloroplast-linked streptomycin resistance allele. The results presented in this thesis identify a mutation in SR116S rRNA, which occurs at the same position as in streptomycin resistant Euglena mutants. The tobacco chloroplast rps12 gene has been characterized. This gene is expressed in a unique way; two separate transcripts encoding different portions of the gene undergo a bimolecular (trans-) splicing event during mRNA maturation. C-terminal rps12 exons 2 and 3 were identified in the inverted repeat regions of the tobacco chloroplast genome. Complementary DNA sequencing of mature rps12 mRNA allowed deduction of the remaining N-terminal (exon 1) sequence. Hybridizations with synthetic oligodeoxyribonucleotide primers complementary to the deduced RNA sequence located the coding region of exon 1 to be 29 kilobasepairs (kbp) downstream of the nearest copy, and 69 kbp away from, and on the opposite DNA strand of, the distal copy, of exons 2 and 3. Northern hybridization analysis and primer extension sequencing of cDNA of rps12 transcripts indicate that exon 1 and exons 2-3 are encoded on separate transcripts. Exon 1 and exons 2-3 are covalently ligated in mature rps12 mRNA. Therefore, the separate transcripts encoding exon 1 and exons 2-3 undergo a trans-splicing event during the maturation of rps12 mRNA. A complete cloned library of tobacco chloroplast DNA was obtained, consisting of overlapping Bam HI restriction fragments. Three new restriction maps of tobacco chloroplast DNA, for the enzymes Sma I, Kpn I, and Bam HI, were derived by two-dimensional gel analysis and a novel computer-aided mapping technique.

The increasing emergence of antibiotic resistant strains of bacteria and fungi is driving the need to increase the production of current antibiotics and produce novel antimicrobial compounds. This study worked to increase the production of cycloheximide and streptomycin antibiotics by co-culturing Streptomyces griseus with other industrially important microbes. 1-3 industrial challenge microbes at a time were added to a culture of S. griseus and allowed to grow for one week in shake flask cultures before harvesting and quantifying antibiotic production. Fifteen different industrial challenge microbes placed in 35 different combinations were used in the study and 17 of these combinations were found to significantly increase antibiotic production after analysis with ANOVA. Antibiotic production was confirmed using bioautograms. Three of the successful different co-cultures were then subjected to a study to see when industrial challenge microbe addition was optimal. Results suggest that the optimal time to add the challenge microbes was 1-3 days following the original S. griseus inoculation. Dead challenge microbes were also added to a culture of S. griseus and it was found that these significantly increased cycloheximide as much as the live co-cultures did. / Department of Biology