During the investigation of the effect of age upon endogenous metabolism, advanced stationary phase cultures of Pseudomonas aeruginosa were found to be susceptible to cold-shock. The phenomenon was apparent through an increased oxygen uptake and an initial absence of extracellular ammonia during subsequent respiration at 30 C, which were shown to be due to the presence of an oxidizable substrate in the suspending fluid. Intracellular enzymes were released following the exposure of these cells to the cold, and a partial protection against damage was afforded by the addition of magnesium ions to the washing and suspending buffer. The storage of a reserve material for utilization during endogenous metabolism could not be demonstrated in cells grown for various periods of time in a chemically-defined medium which contained glucose in excess of that required for growth. Further, when not previously exposed to the cold, an immediate evolution of ammonia was observed when this organism was respired at 30 C irrespective of the medium in which it was cultured or the age at which it was harvested. The ribosome complement was seen to diminish during the prolonged incubation of cultures grown in the chemically-defined media, and was found to disappear almost completely when 48 hr cells, harvested from defined or complete media, were respired at 30 C for a further 48 hr. Chemical fractionation during the respiration period revealed an increase in the concentration of deoxyribonucleic acid and a decrease in the concentrations of ribonucleic acid and protein. Glucosamine was not found to be a major metabolite in the endogenous respiration of this organism. Progressive starvation resulted in a reduction in the constituitive enzymes and/or cofactors involved in the oxidation of glucose, and an ability to adapt to, and oxidize α-ketoglutarate was evident after a period of starvation which had reduced the ribosome complement to negligible proportions. Endogenously produced ammonia and acid-soluble UV-absorbing material were reincorporated upon the addition of an exogenous substrate following respiration for 48 hr, and a concurrent increase was recorded in the concentration of 50S ribosomes. / Land and Food Systems, Faculty of / Graduate

Pseudomonas aeruginosa was shown to constitutively degrade arginine via the arginine dihydrolase pathway to ornithine, which was converted both to glutamate and to putrescine. The conversion of ornithine to glutamate appeared to be the major route of arginine degradation in this organism, and was induced to higher activity after growth of the cells with arginine as the sole source of carbon and nitrogen. P. aeruginosa did not further degrade putrescine constitutively. However, growth of the cells in arginine resulted in a partial induction of succinic semialdehyde dehydrogenase, an enzyme functioning in putrescine degradation. The anabolic ornithine transcarbamylase of P. aeruginosa was repressed after growth of the organism in the presence of arginine. Pseudomonas putida and Pseudomonas fluorescens also possessed the ability to constitutively convert arginine to putrescine via the intermediates, citrulline and ornithine. However, these organisms did not oxidize arginine to the same extent as did P. aeruginosa. P. aeruginosa grew in a mixture of glucose and arginine in the presence of ammonium ions without exhibiting a diauxie effect. Glucose and arginine were oxidized concomitantly when supplied as a mixed substrate, by both growing cells and resting cell suspensions. However, assimilation studies showed that the two substrates were used to serve somewhat different biosynthetic needs. Growth of P. aeruginosa in arginine caused an increase in the rates of transport of arginine, lysine, ornithine and citrulline. Kinetic studies of arginine uptake demonstrated the presence of two uptake systems with different affinities for arginine. Inhibition studies indicated that arginine was transported by two uptake systems: a permease specific for arginine, and, with a lower affinity, for ornithine; and a general permease, which transported all the basic amino acids. Polyamines appeared to be transported by an uptake system which was induced to higher levels after growth of the cells with either arginine or putrescine as the sole source of carbon and nitrogen. P. aeruginosa was found to maintain a stable pool of putrescine when supplied with exogenous ¹⁴C-arginine or ¹⁴C-putrescine, even when the organism had previously been induced to degrade these substrates. A physical fractionation of the cells indicated that the major portion of this pool was located in the soluble cytoplasm. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

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Thesis (M.S. )--Marshall University, 2009. / Title from document title page. Includes abstract. Document formatted into pages: contains 155 p. Includes bibliographical references p. 151-152.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xv, 205 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 163-190).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains ix, 132 p.; also includes graphics (some col.). Includes bibliographical references (p. 112-132). Available online via OhioLINK's ETD Center