Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, October 2007. / Includes bibliographical references (leaves 130-153).

Made available in DSpace on 2014-06-12T15:52:00Z (GMT). No. of bitstreams: 2 arquivo4528_1.pdf: 4234491 bytes, checksum: df9f172b7fcf8fd40b7ea30d3cbb3ac9 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Muitas linhagens de B. subtilis produzem lipopeptídeos, que são compostos anfifílicos com atividades surfactante e antimicrobiana. A produção de lipopeptídeos, associada à capacidade de formação de esporos, contribui para a utilização comercial deste microrganismo no controle biológico de várias doenças de plantas. Neste trabalho, o crescimento, a produção de lipopeptídeos e a esporulação de B. subtilis R14 foram investigados em cultivos descontínuos sob diferentes condições de aeração e temperatura. Ensaios para crescimento em anaerobiose foram realizados em jarras de Gaspak a 37°C, utilizando-se meios de cultivos quimicamente definidos contendo glucose, glucose/piruvato ou glicerol, como fontes de carbono, e (NH4)2SO4 e/ou NaNO3, como fontes de nitrogênio. Para se investigar a produção de lipopeptídeos e esporos sob diferentes condições de aeração e temperatura, cultivos foram realizados em frascos Fernbach, em mesa agitadora. Um meio quimicamente definido, contendo glucose como fonte de carbono e (NH4)2SO4 e NaNO3 como fontes de nitrogênio, foi utilizado em todos os experimentos. Diferentes condições de aeração e temperatura foram testadas através de variações do volume do meio de cultivo (250 mL, 500 mL e 1000 mL), da agitação (150 rpm e 250 rpm) e da temperatura (30°C e 37°C). O crescimento celular foi acompanhado através da determinação do peso seco de células e por espectrofotometria. Os consumos de glucose e de nitrato foram determinados através de métodos espectrofotométricos. A formação de compostos com atividade antimicrobiana e com atividade surfactante foi acompanhada por métodos de difusão em agar e de poder emulsificante sobre hexano, respectivamente. A caracterização parcial dos compostos produzidos foi realizada por cromatografia em camada delgada (CCD). Em anaerobiose, B. subtilis R14 não cresceu em meio contendo glucose como única fonte de carbono. No entanto, o crescimento ocorreu em meios contendo glucose/piruvato ou glicerol como fontes de carbono. Nestes, maiores rendimentos em biomassa foram observados nos meios contendo NaNO3. Em meios com diferentes condições de aeração e temperatura, a produção de composto com atividade antimicrobiana ocorreu em todos os cultivos durante a fase de crescimento, havendo degradação quando a fase de declínio foi atingida. Condições de restrição de oxigênio favoreceram a produção de composto com atividade antimicrobiana, entretanto, o aumento excessivo da restrição foi desfavorável à produção deste composto. O maior rendimento em produto com atividade antimicrobiana foi obtido a 30°C, ao passo que a maior produtividade ocorreu a 37°C. A produção de composto com atividade surfactante também ocorreu em todos os cultivos durante a fase de crescimento. A restrição de oxigênio e a temperatura de 30°C também favoreceram a produção deste composto. Em todas as situações analisadas, houve produção de esporos, mas a condição de maior temperatura e agitação (37°C e 250 rpm) favoreceu a esporulação. Ensaios em CCD revelaram que os compostos produzidos eram o lipopeptídeo surfactina e um outro com atividade antimicrobiana

[No abstract available] / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

Cultures of Bacillus subtilis growing in an iron-deficient medium produced coproporphyrin III (coproporphyrin) and phenolic acids. (2,3-dihydroxybenzoylglycine (DHBG), 2,3-dihydroxybenzoic acid (DHB), or both). (DHB(G) refers to DHB or DHBG, or both compounds). Phenolic acid production was proportional to the amount of iron present, and occurred logarithmically, parallelling growth. In the presence of DHB, lower levels of iron inhibited phenolic acid production, so that the actual inhibition of synthesis may involve the Fe(+3): (DHB(G))₃ complex. Accumulatlon of DHB(G) was influenced by the levels of aromatic amino acids, anthranilic acid, and histidine in the medium. In vitro experiments demonstrated that DHB was formed from chorismic acid. In vivo and in vitro experiments with strain B-1471 showed that DHB was coupled to added glycine to form DHBG. Disappearance of DHB(G) was observed in all strains studied, but oxidation did not occur. Phenolic acid production always preceded coproporphyrin production. Phenolic acids have very strong affinities for ferric iron. Their production may therefore allow the scavenging of the last traces of iron from the medium for hemin synthesis. The relationship between phenolic acid and coproporphyrin production was borne out by the following observations: (i) a higher level of iron was required to prevent coproporphyrin production than phenolic acid production (ii) the Fe(+3) (DHB(G))₃ complex was a more potent inhibitor of coproporphyrin production than iron alone (iii) a mutant blocked at σ-aminolevulinic acid synthetase did not produce phenolic acids during iron-deficient growth (iv) serine auxotrophs produced much lower levels of coproporphyrin and phenolic acids than the wild-type strain (v) some mutants defective in phenolic acid production produced low levels of coproporphyrin, whereas one strain of this type produced elevated levels of coproporphyrin. Compounds known to inhibit normal functioning of the tricarboxylic acid cycle decreased coproporphyrin production in all strains studied. These inhibitors reduced DHBG excretion, but had no effect on DHB production. A number of analogs of DHB inhibited DHB(G) accumulation to varying degrees, depending upon their structure. The most potent inhibitors were m-substituted derivatives of benzoic acid. Two sideramines, ferrichrome and ferrioxamine, inhibited DHBG production in strain B-1471. The inhibitory action of ferrichrome was shown to be due to its ability to mediate cellular uptake of low levels of iron. The capacity of B. subtilis for iron uptake was increased about 20-fold by growing the cells in an iron-deficient medium. Under these conditions, the addition of low levels of phenolic acids increased both the rate and extent of iron uptake. Mutants unable to synthesize normal levels of phenolic acid were shown to have a reduced capacity for iron uptake after growth in an iron-deficient medium. Mutants resistant to 8-hydroxyquinoline had an increased capacity for iron-uptake under these conditions. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

No description available.

No description available.

Les bactéries peuvent favoriser la formation de calcite. Leur utilisation au sein des matériaux cimentaires permettrait de colmater des fissures avec ce produit compatible et durable. L'objectif principal de cette thèse est de comprendre les mécanismes de la biocicatrisation des matériaux cimentaires afin d’accélérer la cinétique et maximiser le colmatage de fissures importantes (>200 µm). L'approche de biocicatrisation étudiée consiste à imprégner les fissures à l'aide d'un milieu de culture (milieu précurseur) contenant des bactéries. 3 aspects sont étudiés : les mécanismes abiotiques de cicatrisation (sans bactéries) des fissures de mortier, la croissance bactérienne in vitro, et la biocicatrisation des fissures de mortier. L'étude des mécanismes abiotiques porte sur l'autocicatrisation naturelle et sur l'influence des milieux précurseurs (urée, lactate de calcium et gluconate de calcium) sur la cicatrisation. L'influence d'une carbonatation initiale des fissures est aussi évaluée. L'étude sur les bactéries vise à suivre leur développement et à sélectionner le milieu de culture. L'étude de la biocicatrisation consiste à suivre la cicatrisation de fissures soumises aux traitements bactériens sélectionnés. Des fissures importantes (>200 µm) peuvent être réduites à 80 % par l'action des bactéries. Certains précurseurs ont un rôle important sur la cicatrisation de fissures fraichement ouvertes : en contact avec la pâte de ciment ils favorisent la formation d'ettringite qui comble partiellement les fissures. Il n'y a pas d'effet de ces précurseurs sur les fissures préalablement carbonatées. / Certain bacteria are able to promote calcite formation. Their use in the material allows the sealing of cracks by calcite, which is a compatible and durable product. The objective of this research is to achieve a better understanding of the biocicatrisation mechanisms in cementitious materials in order to accelerate its kinetics and maximize the sealing of large cracks (>200 µm). The studied bio-healing approach consists of soaking the cracks with a culture medium (precursor medium) containing bacteria. 3 aspects are investigated: abiotic healing mechanisms (without bacteria) of mortar cracks, in vitro bacterial growth, and bio-healing of mortar cracks. The study of abiotic mechanisms focuses on natural self-healing and addresses the influence of precursors (urea, calcium lactate, and calcium gluconate) on the healing process. The influence of the initial carbonation of cracks is also evaluated. The study of bacteria consists of monitoring bacterial growth and selecting the culture medium. The study of bio-healing aims to monitor the healing of cracks subjected to the selected bacterial treatments. Bacteria are improving the healing ability of the material. Large cracks (>200 µm) are reduced by 80 % through bacteria. Precipitation precursors have an important role in the healing of newly opened cracks: calcium lactate and calcium gluconate, in contact with the cement paste, promote the formation of ettringite, which partially fills the cracks. There are no effects of these precursors in previously carbonated cracks.

Résumé indisponible. / Résumé indisponible.

The purpose of this study was to compare the pathology caused by two bacterial species, Bacillus subtilis and Bacillus thuringiensis, in European corn borer larvae. The study consisted of: (1) a determination of the mortality of larvae that had ingested various concentrations of bacterial spores; (2) light microscopic examination of midgut tissues of larvae treated with various concentrations of bacterial spores, and (3) examination of midgut tissues of treated larvae with transmission electron microscopy.The results of the mortality study indicated that B. subtilis did not cause mortality in corn borer larvae. Light and electron microscopy did not reveal any pathological damage to midgut tissues of larvae treated with B. subtilis. It was observed that there was an increase in the amount of peritrophic membrane produced in the larvae treated with B. subtilis. These larvae were also observed to be sluggish and have diahrrea, suggesting a mild disease state.Mortality in larvae treated with B. thuringiensis varied with the concentration of spores ingested, and ranged as high as 100 percent. The mortality data were used to select three spore concentrations, corresponding to 25 percent, 50 percent, and 90 percent mortality levels. Larvae treated with B. thuringiensis spores in these concentrations were then examined by light microscopy. The pathology observed included slight swelling and vacuolation of the epithelial cells, cellular disruption, and complete breakdown of the epithelial tissue and subsequent bacteremia. It was observed that the degree of pathology increased with an increase in the bacterial spore concentration.Electron microscopic examination of midgut of B. thuringiensis treated larvae revealed the following pathological symptoms: decrease in apical microvilli, decrease in microvilli of goblet cells, and decrease in basal infoldings of plasma membrane.

Thesis (M.Sc.) -- University of Adelaide, Dept. of Biochemistry, 1981.