Dissertation (D.P.H.)--University of Michigan.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [173]-183.

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Made available in DSpace on 2016-02-05T18:29:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-19. Added 1 bitstream(s) on 2016-02-05T18:33:30Z : No. of bitstreams: 1 000856534.pdf: 1786488 bytes, checksum: 60ef6090b71a2cdd53c351b1c89d36f9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Uma das grandes preocupações ecológicas atuais refere-se ao impacto ambiental causado pela liberação antrópica de metais pesados em ambientes naturais, uma vez que esses poluentes são extremamente ubíquos e persistentes. Em altas concentrações metais pesados são extremamente tóxicos a bactérias, sendo capazes de influenciar na sua densidade e atividade metabólica. Por sua vez, bactérias são capazes de desenvolver mecanismos de resistência a metais pesados sendo importantes em estudos de biorremediação de áreas contaminadas por metais pesados. Portanto, o objetivo do presente trabalho foi analisar a ocorrência e distribuição de bactérias resistentes a metais pesados na Baía do Araça em São Sebastião, SP. Do total de cepas isoladas, 12% foram sensíveis a todos os metais. Foi possível observar que a maior porcentagem de cepas resistentes se encontravam na região de sublitoral que é mais próxima ao canal de São Sebastião onde se concentra a atividade portuária. As cepas isoladas foram mais resistentes ao Cr, seguido de Zn, Cd e Cu. Em relação a concentração mínima inibitória, para o Cd foram poucas as cepas que resistiram a concentrações maiores que 200 μg mL-1. Já para o Cr, 36% das cepas cresceram mesmo na concentração de 3200 μg mL-1. Para Zn e Cu, poucas cepas (4% e 2%, respectivamente) cresceram na concentração 1600 μg mL-1 e nenhuma conseguiu resistir à maior concentração (3200 μg mL-1). Bacillus sp foi o genero com maior frequência de isolados, o que pode sugerir dominância em áreas contaminadas por metais pesados, especialmente as espécias Bacillus cereus e Bacillus pumilus. Staphyloccus sp, Planococcus maritmus e Vibrio alginoticus também foram isolados sugerindo potencial para utilização em processos de biorremediação / One of the major ecological concerns, nowadays, refers to anthropogenic environmental impact caused by heavy metals release in diverses natural environments, since these pollutants are extremely persistent and pervasive. At high concentration heavy metals are extremely toxic to bacteria, being able to influence the density and metabolic activity. However, bacteria are capable to develop heavy metal resistance mechanisms in the environment, being important in bioremediation of contaminated areas. Therefore, the purpose of the study was to assess the occurrence and distribution of heavy metal resistance bacteria in Araça Bay, São Sebastião - SP. 12% of the isolated bacteria were sensitive to all metals. It was observed that the highest percentage of resistant strains were in the subtidal region that is closest to the São Sebastião channel, where port activity are concentrated. Bacterial isolates were more resistant to Cr, followed by Zn, Cd and Cu. Regarding the minimum inhibitory concentration, a lower number of strains resisted levels greater than 200 mg L-1 for Cd. While for Cr, 36% of the strains grew even at a concentration of 3200 mg L-1. For Zn, Cu, few strains (4% and 2%, respectively) grew in higher concentrations like 1600 mg L-1 and none could withstand the highest concentration (3200 mg L-1). Bacillus sp was the most isolated genera and may be a dominant genre in heavy metal contaminated areas, especially species Bacillus pumilus and Bacillus cereus. Staphylococcus sp, Planococcus maritmus and Vibrio aginoliticus were also isolated and have potential for use in bioremediation of contaminated sites

Orientador: Ana Julia Fernandes Cardoso de Oliveira / Banca: Dejanira de Franceschi de Angelis / Banca: Edison Barbieri / Resumo: Uma das grandes preocupações ecológicas atuais refere-se ao impacto ambiental causado pela liberação antrópica de metais pesados em ambientes naturais, uma vez que esses poluentes são extremamente ubíquos e persistentes. Em altas concentrações metais pesados são extremamente tóxicos a bactérias, sendo capazes de influenciar na sua densidade e atividade metabólica. Por sua vez, bactérias são capazes de desenvolver mecanismos de resistência a metais pesados sendo importantes em estudos de biorremediação de áreas contaminadas por metais pesados. Portanto, o objetivo do presente trabalho foi analisar a ocorrência e distribuição de bactérias resistentes a metais pesados na Baía do Araça em São Sebastião, SP. Do total de cepas isoladas, 12% foram sensíveis a todos os metais. Foi possível observar que a maior porcentagem de cepas resistentes se encontravam na região de sublitoral que é mais próxima ao canal de São Sebastião onde se concentra a atividade portuária. As cepas isoladas foram mais resistentes ao Cr, seguido de Zn, Cd e Cu. Em relação a concentração mínima inibitória, para o Cd foram poucas as cepas que resistiram a concentrações maiores que 200 μg mL-1. Já para o Cr, 36% das cepas cresceram mesmo na concentração de 3200 μg mL-1. Para Zn e Cu, poucas cepas (4% e 2%, respectivamente) cresceram na concentração 1600 μg mL-1 e nenhuma conseguiu resistir à maior concentração (3200 μg mL-1). Bacillus sp foi o genero com maior frequência de isolados, o que pode sugerir dominância em áreas contaminadas por metais pesados, especialmente as espécias Bacillus cereus e Bacillus pumilus. Staphyloccus sp, Planococcus maritmus e Vibrio alginoticus também foram isolados sugerindo potencial para utilização em processos de biorremediação / Abstract: One of the major ecological concerns, nowadays, refers to anthropogenic environmental impact caused by heavy metals release in diverses natural environments, since these pollutants are extremely persistent and pervasive. At high concentration heavy metals are extremely toxic to bacteria, being able to influence the density and metabolic activity. However, bacteria are capable to develop heavy metal resistance mechanisms in the environment, being important in bioremediation of contaminated areas. Therefore, the purpose of the study was to assess the occurrence and distribution of heavy metal resistance bacteria in Araça Bay, São Sebastião - SP. 12% of the isolated bacteria were sensitive to all metals. It was observed that the highest percentage of resistant strains were in the subtidal region that is closest to the São Sebastião channel, where port activity are concentrated. Bacterial isolates were more resistant to Cr, followed by Zn, Cd and Cu. Regarding the minimum inhibitory concentration, a lower number of strains resisted levels greater than 200 mg L-1 for Cd. While for Cr, 36% of the strains grew even at a concentration of 3200 mg L-1. For Zn, Cu, few strains (4% and 2%, respectively) grew in higher concentrations like 1600 mg L-1 and none could withstand the highest concentration (3200 mg L-1). Bacillus sp was the most isolated genera and may be a dominant genre in heavy metal contaminated areas, especially species Bacillus pumilus and Bacillus cereus. Staphylococcus sp, Planococcus maritmus and Vibrio aginoliticus were also isolated and have potential for use in bioremediation of contaminated sites / Mestre

Orientador: Antonio Carlos Paulillo / Banca: Lúcia Baldassi / Banca: Ednardo Rodrigues Freitas / Banca: Luiz Augusto do Amaral / Banca: Angelo Berchieri Júnior / Resumo: Para as aves, a água é o nutriente essencial mais importante, sendo responsável pela maioria das funções do organismo. Em 2004 avaliou-se a qualidade da água utilizada em 20 granjas de postura comercial de Bastos/SP, Brasil, colhendo-se amostras dos poços, reservatórios e galpões. Nas amostras dos poços determinou-se a concentração de alumínio, cálcio, chumbo, cloro, cobre, enxofre, ferro, fósforo, magnésio, nitrito, potássio, selênio, sódio, sulfatos, zinco, pH e dureza. Nas amostras colhidas nos períodos de chuva e estiagem, realizaram-se as contagens de coliformes totais e fecais, estreptococos fecais, Pseudomonas aeruginosa e pesquisou-se Escherichia coli , Salmonella sp e Pasteurella multocida. A dureza da água de 35% das propriedades apresentou valores entre 60 - 110 mg CaCO3/L, em 45% o pH foi =6 e nenhuma apresentou pH >8. Entre as propriedades 50% apresentaram níveis de NO3-N =3 mg/L. Para todos os microrganismos pesquisados, o galpão de aves apresentou as maiores taxas de amostras positivas nos períodos de chuva e estiagem, ocorrendo a diminuição da % de isolamento no período de estiagem. A contagem bacteriana foi maior nas amostras de água do galpão, nos dois períodos de colheita. No reservatório, após a adição de cloro à água, o número de coliformes totais diminuiu e não houve detecção de coliformes fecais, estreptococos fecais e Pseudomonas aeruginosa. Em nenhuma das 440 amostras de água analisadas, nos períodos de chuva e estiagem, foram detectadas Salmonella sp e Pasteurella multocida. / Abstract: Water is considered the most important essential nutrient, for chickens, being responsible for most of the organism functions. In 2004, the quality of the water used in 20 laying hens farms from Bastos/SP, Brazil, was tested, picking samples from wells, water tanks and laying hens house. It was determinated in the well-water samples the concentration of aluminum, calcium, lead, chlorine, copper, iron, phosphorus, magnesium, nitrate, nitrite, potassium, selenium, sodium sulfate, zinc, pH and strength. In the water samples, collected in the rainy and dry seasons, were counted the total coliforms, fecal coliforms, fecal streptococci, Pseudomonas aeruginosa and was done the research of Escherichia coli , Salmonella sp e Pasteurella multocida. The strengths values of 35% of the farms was between 60-110 mg CaCO3/L, in 45%, the pH was =6 and no farms presented pH >8. Among the farms 50% presented levels of NO3-N =3. For all microorganism researched, the laying hens house presented the higher taxes of positives samples during the rainy or dry seasons, occurring a reduction of isolation taxes in the dry season. Both periods of collection the number of total coliforms; fecal coliforms; streptococci and Pseudomonas aeruginosa was higher in the samples from the laying hens houses. In the water tank, after chlorine addiction to the water, the number of total and fecal coliforms decreased and there wasn't detection of fecal streptococci and Pseudomonas aeruginosa. In none of the 440 water samples analyzed, in the rainy nor in the dry seasons, Salmonella sp and Pasteurella multocida were detected. / Doutor

Made available in DSpace on 2014-06-11T19:30:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-19Bitstream added on 2014-06-13T20:07:37Z : No. of bitstreams: 1 boarini_l_me_jabo.pdf: 330765 bytes, checksum: 5a2e1936a8b0a2fe8933d469fc9b46a7 (MD5) / A suinocultura vem ganhando espaço no mercado brasileiro, atualmente o interesse por alimentos saudáveis trouxe a carne suína como aliada e não mais como vilã. A partir disso, novas tecnologias como sistemas de confinamento, foram adotadas a fim de obter melhorias que visam principalmente à higiene do processo, alimentação balanceada dos animais e instalações adequadas. Nesse enquadramento, doenças infecciosas entéricas representam um problema importante na suinocultura, e estão envolvidas com grandes perdas econômicas e contaminação da carcaça comercializada. Considerando estes aspectos, o trabalho objetivou identificar Clostridium perfringens e Salmonella spp., a fim de alertar o setor suinícola sobre os riscos ainda disseminados que causam enfermidades nos suínos e contaminam os produtos que serão comercializados; e correlacionar a presença de Clostridium perfringens com interferências no ganho de peso dos animais. Foram realizadas contagens bacterianas para Clostridium spp. que apresentaram médias de 1,2x105 UFC/mL na primeira coleta e 7,88x102 UFC/mL na segunda coleta do confinamento, e nas amostras do frigorífico contou-se 1,8x104 UFC/mL. Os resultados obtidos por PCR foram positivos apenas para a toxina alfa (cpa), caracterizando uniformidade dos positivos (25%) para Clostridium perfringens tipo A do confinamento e 46,4% do frigorífico. Para Salmonella spp. com o gene invA foram detectados 9,5% de positivos nos animais do confinamento e 21,4% das amostras do frigorífico. E Salmonella Typhimurium com o gene fliC, foram positivas 3,57% no confinamento e 8,33% no frigorífico. Foi possível concluir que Clostridium perfringens e Salmonella spp. foram... / Swine production is becoming more popular in the Brazilian market, currently interest in healthy foods brought swine as an ally and not as a villain. From this, new technologies such as confinement systems were adopted in order to achieve improvements aimed primarily to process hygiene, a balanced diet of animals and adequate facilities. In this framework, enteric infectious diseases represent a important problem in the swine production, and are involved with large economic losses and contamination of carcass marketed. Considering these aspects, the study aimed to identify Clostridium perfringens and Salmonella spp. in order to alert the swine sector still scattered about the risks that cause diseases in swine and contaminate the products to be marketed; and correlating the presence of Clostridium perfringens with interference on weight gains of animals. Bacterial counts were performed for Clostridium spp presenting averages of 1.2 x105 CFU/ mL in the first test and 7.88 x102 CFU / mL in the second collection of confinement, and the samples of slaughterhouse told by 1.8 x104 CFU/ mL. The results obtained by PCR were positive only for the alpha-toxin (cpa), featuring uniformity of positive samples (25%) for Clostridium perfringens type A of confinement and 46.4% of the slaughterhouse. For Salmonella spp. with the invA gene were detected 9.5% of positive animals in confinement and 21.4% of samples from the slaughterhouse. And Salmonella Typhimurium with the gene fliC, were positive 3.57% in the confinament and 8.33% in the slaughterhouse. It was concluded that Clostridium perfringens and Salmonella spp. were... (Complete abstract click electronic access below)

This thesis describes dip tank field trials and laboratory investigations on the acaricide Amitraz. Amitraz is a triazapenta- diene compound which is relatively unstable in fouled dip washes. The field trials were conducted on the farm Sea View according to the "Total Replacement Method" and on the farm Sea Ways according to the "Lime Stabilization Method" of dipping. The results of these trials showed that Amitraz was stable in clean dip washes, and under conditions of high pH resulting from the addition of slaked lime to the dip wash. Using mixed bacterial populations optimum conditions for degradation of Amitraz in the laboratory were determined. Bacterial cultures degraded Amitraz most efficiently in media supplemented with yeast extract or with a high content of sterile cattle faeces. Amitraz concentrations were determined by gas chromatography. A culture. efficient at degrading Amitraz was enriched from a dip tank sludge inoculum. From this culture ten bacterial isolates were identified; nine of these were of the genus Pseudomonas and one was an Achromobacter sp. Experiments with both mixed and pure cultures demonstrated that bacterial degradation of Amitraz was by the process of co-metabolism. The existence of four degradation products was shown using thin layer chromatography. Tentative identification of two of the products was made.

Philosophiae Doctor - PhD (Biochemistry) / While the many completely sequenced genomes of bacterial pathogens contain all the determinants of the host-pathogen interaction, and also every possible drug target and recombinant vaccine candidate, computational tools for selecting suitable candidates for further experimental analyses are limited to date. The overall objective of my PhD project was to attempt to design reusable systems that employ the two most important features of bacterial evolution, horizontal gene transfer and adaptive mutation, for the identification of potentially novel virulence-associated factors and possible drug targets. In this dissertation, I report the development of two novel technologies that uncover novel virulence-associated factors and mechanisms employed by bacterial pathogens to effectively inhabit the host niche. More importantly, I illustrate that these technologies may present a reliable starting point for the development of screens for novel drug targets and vaccine candidates, significantly reducing the time for the development of novel therapeutic strategies. Our initial analyses of proteins predicted from the preliminary genomic sequences released by the Sanger Center indicated that a significant number appeared to be more similar to eukaryotic proteins than to their bacterial orthologs. In order determine whether acquisition of genetic material from eukaryotes has played a role in the evolution of pathogenic bacteria, we developed a system that detects genes in a bacterial genome that have been acquired by interkingdom horizontal gene transfer.. Initially, 19 eukaryotic genes were identified in the genome of Mycobacterium tuberculosis of which 2 were later found in the genome of Pseudomonas aeruginosa, along with two novel eukaryotic genes.Surprisingly, six of the M. tuberculosis genes and all four eukaryotic genes in P. aeruginosa may be involved in modulating the host immune response through altering the steroid balance and the production of pro-inflammatory lipids. We also compared the genome of the H37Rv M. tuberculosis strain to that of the CDC- 1551 strain that was sequenced by TIGR and found that the organisms were virtually identical with respect to their gene content, and hypothesized that the differences in virulence may be due to evolved differences in shared genes, rather than the absence/presence of unique genes. Using this observation as rationale, we developed a system that compares the orthologous gene complements of two strains of a bacterial species and mines for genes that have undergone adaptive evolution as a means to identify possibly novel virulence –associated genes. By applying this system to the genome sequences of two strains of Helicobacter pylori and Neisseria meningitidis, we identified 41 and 44 genes that are under positive selection in these organisms, respectively. As approximately 50% of the genes encode known or potential virulence factors, the remaining genes may also be implicated in virulence or pathoadaptation. Furthermore, 21 H. pylori genes, none of which are classic virulence factors or associated with a pathogenicity island, were tested for a role in colonization by gene knockout experiments. Of these, 61% were found to be either essential, or involved in effective stomach colonization in a mouse infection model. A significant amount of strong circumstantial and empirical evidence is thus presented that finding genes under positive selection is a reliable method of identifying novel virulence-associated genes and promising leads for drug targets. / South Africa

Pseudomonas aeruginosa is a dreaded opportunistic pathogen that causes severe and often intractable infections in immunocompromised and critically ill patients. This bacterium is also the primary cause of fatal lung infections in patients with cystic fibrosis and a leading nosocomial pathogen responsible for nearly 10% of all hospital-acquired infections. P. aeruginosa is intrinsically recalcitrant to most classes of antibiotics and has the ability to acquire additional resistance during treatment. In particular, resistance to the widely used β-lactam antibiotics is frequently mediated by the expression of AmpC, a chromosomally encoded β-lactamase that is ubiquitously found in P. aeruginosa strains. This dissertation delved into the role of a recently reported chromosomal β-lactamase in P. aeruginosa called PoxB. To date, no detailed studies have addressed the regulation of poxB expression and its contribution to β-lactam resistance in P. aeruginosa. In an effort to better understand the role of this β-lactamase, poxB was deleted from the chromosome and expressed in trans from an IPTG-inducible promoter. The loss of poxB did not affect susceptibility. However, expression in trans in the absence of ampC rendered strains more resistant to the carbapenem β-lactams. The carbapenem-hydrolyzing phenotype was enhanced, reaching intermediate and resistant clinical breakpoints, in the absence of the carbapenem-specific outer membrane porin OprD. As observed for most class D β-lactamases, PoxB was only weakly inhibited by the currently available β-lactamase inhibitors. Moreover, poxB was shown to form an operon with the upstream located poxA, whose expression in trans decreased pox promoter (Ppox) activity suggesting autoregulation. The transcriptional regulator AmpR negatively controlled Ppox activity, however no direct interaction could be demonstrated. A mariner transposon library identified genes involved in the transport of polyamines as potential regulators of pox expression. Unexpectedly, polyamines themselves were able induce resistance to carbapenems. In summary, P. aeruginosa carries a chromosomal-encoded β-lactamase PoxB that can provide resistance against the clinically relevant carbapenems despite its narrow spectrum of hydrolysis and whose activity in vivo may be regulated by polyamines.