Corynebacterium pseudotuberculosis is a pathogenic bacterium which cause suppurative infection mainly in sheep, goats, horses, and other species. It plays a major role in the economy of sheep production worldwide. It produces a toxic phospholipase D which may be involved in pathogenesis. The relationship of physiologic differences between the two biovars of the organism to rates of growth and toxin production are not known. In this work, isolates of C.pseudotuberculosis were examined for relative ability to grow in brain heart infusion broth and a semidefined medium. The effects of carbohydrate source and the presence or absence of various ions were also examined. Results revealed no statistically significant differences between isolates or biovars in any characteristic studied, including growth rate, pH change during growth and PLD production. The semidefined medium provides a reasonable alternative to more complex media for further work in purification of PLD and study of its structure and function.

No description available.

Thesis (doctoral)--Universität Zürich, 1906. / Includes bibliographical references.

Thesis (Ph. D.)--Cornell, 1912. / Bibliography, p. 107-110.

Made available in DSpace on 2014-06-11T19:31:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-23Bitstream added on 2014-06-13T19:01:10Z : No. of bitstreams: 1 antonio_t_dr_araiq.pdf: 685450 bytes, checksum: 38953886194d585fde26a8d2130709e0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Mutantes foram obtidos através de tratamento mutagênico dos esporos de S. clavuligerus ATCC 27064 com metil-metanosulfonato. Um total de 822 colônias, obtidas por repiques sucessivos, foram selecionadas em testes qualitativos e/ou quantitativos. O melhor mutante S. clavuligerus 45.41, mostrou-se de duas a quatro vezes mais produtivo que a linhagem selvagem, e manteve-se estável após 35 repiques sucessivos ao longo deste estudo. O comportamento das linhagens foi investigado pela adição de diferentes diaminas ao meio de cultivo, uma a uma, na ausência de lisina. Também se investigou duas fontes distintas de C, além de compostos como o ácido 2,6- diaminopimélico. Um planejamento de dois fatores (cadaverina e lisina), três níveis, baseado no ponto central, faces centradas, indicou que a adição de lisina aumenta a produção de CefC para ambas as linhagens. O efeito positivo da cadaverina foi observado principalmente na linhagem mutante 45.41. Resultados obtidos em processo de batelada, em biorreator de bancada confirmaram as diferenças observadas entre as linhagens nos cultivos em frascos agitados. Procedimento de mutagênese clássica foi utilizado em conjunto com critérios bem definidos para se estabelecer um meio de cultura apropriado, com o objetivo de alcançar um aumento significativo da produção de CefC. Este é o primeiro estudo utilizando um mutante de S. clavuligerus obtido por mutagênese clássica, cuja produção de CefC é de três vezes maior que a da linhagem selvagem, em meios contendo diaminas / Mutants were obtained by treating S. clavuligerus ATCC 27064 spores with methyl-methanesulfonate. A total of 822 colonies, obtained by successive sampling, were selected by qualitative and/or quantitative tests. The best mutant, S. clavuligerus 45.41, was two to four times more productive than the wild-type strain, and remained stable even after 35 successive samplings throughout the study. Strains behavior was investigated by adding different diamines in media, one by one, in the absence of lysine. Also investigated two different sources of C, and compounds such as 2,6-diaminopimelic acid. The two-factor (cadaverine and lysine), three-level, central composite-based, face-centered experimental design indicates that adding lysine increases CephC production for both strains alike. The positive effect of cadaverine was observed mainly in the Mutant 45.41 strain. Results obtained in batch-processes in a bench-scale bioreactor confirmed differences among strains observed in shaken flasks cultures. Classical mutagenesis procedures in conjunction with the adoption of well-defined criteria to establish an appropriate culture medium promoted a significant improvement in CephC production. It is the first study indicating an increase in CephC production in media containing diamines employing a mutant of S. clavuligerus obtained by classical mutagenesis

Thesis (M.S.P.H.)--University of Michigan, 1939.

Thesis (M.S.)--University of Michigan, 1960.

Thesis (M.S.)--University of Michigan, 1960.

Thesis (M.S.P.H.)--University of Michigan, 1939.

A mechanistic model was developed, which described the growth of a bacterial colony on an agar medium. Diffusion of substrate (nutrients/oxygen) through the colony are considered. Rate of substrate use by the organisms is assumed to follow Michaelis-Menton kinetics for substrate concentrations between prescribed limits. Above and below the prescribed concentration limits, the substrate use rate is assumed constant and zero, respectively. Supply of substrate to the colony was assumed to be non-limiting. Under these conditions, the model predicted that diffusion of substrate through the colony will eventually control colony growth. It also described a slower eponential growth rate of the colony when the organisms utilized an alternate substrate for one that became deficient throughout a portion of the colony, and a constant linear growth rate when an alternate substrate was not utilized. Consistent with published literature, a mathematical description of substrate supply through the agar indicated that, under normal conditions, glucose supply through the agar to the colony would not be expected to limit colony growth before oxygen diffusion through the colony limited growth.