The bacterium Chlamydia trachomatis as well as the Human Immunodeficiency virus-1 (HIV-1) are sexually transmitted pathogens; both can infect monocytes/ macrophages and have an obligate intracellular replication cycle. It has been hypothesized that sexually transmitted infections (STIs), including genital Chlamydia, enhance HIV-1 transmission; yet, the underlying biological mechanisms remain unclear. The pathogen¡¯s common biology makes it possible that C. trachomatis and HIV mutually affect each other¡¯s replication cycle during monocyte/macrophage co-infection. To test this hypothesis we used two different bacteria strains in an in vitro HIV co-infection model: Latently virus-infected U1 promonocytes were either inoculated with C. trachomatis serovar D or serovar L2. It was found that serovar D, but not the LGV serovar L2, quickly and significantly reactivates integrated HIV-1 provirus. This reactivation depends on viable bacteria but seemingly neither on a microbial pathogen-associated molecular pattern (PAMP) nor on de novo gene expression by C. trachomatis. Hence, it could be triggered by a preformed protein that the bacterium translocates into the human cell. Because virus production occurs in Chlamydia-infected as well as Chlamydia-free cells and cannot be induced by conditioned culture medium, we propose a cell contact-dependent signal to U1 bystander cells. The HIV reactivation mechanism involves NF-kappaB activation but is independent of eukaryotic de novo protein translation. In summary, the findings might describe a novel Chlamydia-mediated HIV-1 reactivation mechanism from latently infected cells.

No description available.

In the 1870s a debate over the spontaneous generation of microorganisms took place in Britain. Much opposition to the doctrine of spontaneous generation came from the Victorian scientific naturalists, especially John Tyndall, Professor of Natural Philosophy at the Royal Institution, London. This thesis provides an understanding of and explanations for the beliefs surrounding the spontaneous generation debate, particularly with regard to Victorian scientific naturalism and its relationship to medicine. Spontaneous generation threatened some of the fundamental tenets of naturalism. Furthermore, Tyndall clearly related his opposition to spontaneous generation to his support for the germ theory which he used as a vehicle for advocating a scientific approach to medicine. The thesis concludes that Tyndall's campaign for scientific medicine was part of the scientific naturalists' campaign to spread the naturalistic world-view and to gain cultural leadership. The spontaneous generation debate is examined in detail. The shift in experimental paradigm away from physical conditions towards a bacteriological approach is described. Chapter 5 examines the threats an acceptance of spontaneous generation posed to naturalism in terms of evolution, protoplasm and naturalistic explanations of disease. The effects of Tyndall's campaign for the germ theory on the medical profession are described. In order to understand how scientific knowledge was introduced into medicine, Chapter 6 examines the work of key medical scientists in the field of pathology with reference to their involvement in the spontaneous generation debate and in particular the reasons for their acceptance or rejection of the germ theory. Chapter 7 shows how the spontaneous generation debate impacted the domain of public health from the 1870s-1890s by means of a detailed examination of handbooks of sanitation and hygiene. The gradual introduction of results from the spontaneous generation debate into these works demonstrates the importance of the spontaneous generation debate in forming a bridge from the medical knowledge of the 1860s to the new bacteriology of the 1880s.

Microorganisms are critical to the functioning of terrestrial and aquatic ecosystems and may also play a role in the functioning of the atmosphere. However, little is known about the diversity and function of microorganisms in the atmosphere. To investigate the forces driving the assembly of bacterial microbial communities in the atmosphere, I measured temporal variation in bacterial diversity and composition over diurnal and inter-day time scales. Results suggest that bacterial communities in the atmosphere markedly vary over diurnal time scales and are likely structured by inputs from both local terrestrial and long-distance sources. To assess the potential functions of bacteria and fungi in the atmosphere, I characterized total and potentially active communities using both RNA- and DNA-based data. Results suggest there are metabolically active microorganisms in the atmosphere that may affect atmospheric functions including precipitation development and carbon cycling. This dissertation includes previously published and unpublished co-authored material.

No description available.

This problem includes, first, the isolation and identification of microorganisms which utilized the hydrocarbon insecticide as a sole source of carbon and energy; second, a determination of the effect on plants sprayed with the hydrocarbon medium as compared with the effect on plants sprayed with the hydrocarbon medium containing a good growth of hydrocarbon-utilizers; and third, a determination of the ability of laboratory stock cultures of organisms to utilize or remain alive in the hydrocarbon medium.

Many intervention methods theoretically have the potential to eliminate microorganisms. However, they do not perform efficiently once applied to fruits and vegetables. In this study Salmonella Typhimurium LT2 and hydrogen peroxide (H2O2) were used as model systems on 6 different types of produce to determine the effect of produce surface characteristics on sanitizer effectiveness. Microbial attachment on produce surfaces was induced after 3 h of drying at 24°C and high relative humidity (RH). Afterwards, produce was stored for 3 subsequent days and washed with sterilized tap water for 5, 10 and 15 minutes to separate weakly from strongly attached microorganisms from the produce surface. The strongly attached microorganisms were then treated with 3% H2O2 for 1, 3, and 5 minutes. These results were compared to the log reduction curves obtained with a pure liquid culture and 3% H2O2. Additionally, contact angle of water and diiodomethane on each type of surface were measured and used as indicator of wettability, and for calculating surface tension characteristics of the produce surfaces. Then these surface characteristics were related to the bacterial attachment and population reduction values obtained after applying the treatments. In general, the geometric mean equation was the most useful in predicting the surface tension values of produce surface and the polar and non-polar components of produce surface tension. Our results suggest that surface properties, such as roughness and surface tension of fruits and vegetables are important factors limiting decontamination. These surface properties allow the formation of micro-air pockets within the rough surface, thus contributing to create a protective environment for microorganisms and reducing the effectiveness of the chemical aqueous based intervention methods applied. Wettable surfaces (water contact angle < 90°) allowed more bacteria to attach after the washing and H2O2 chemical treatments. Roughness and surface polarity are intrinsic characteristics of produce surfaces which affect wettability and the spreading and penetration of the sanitizer treatment on the produce surface. Rough surface and porosity, considered an extreme case of roughness, enhance a deeper cell internalization and a protective environment for bacteria.

The purpose of this report was to investigate how the abiotic factors (temperature, pH, nutrients, oxygen levels and water content) would affect the decomposition of oil-contaminated soil and how a variance in structured soil would affect the decomposition-rate. A minor field-study was made and soil where structured in five different ways (one was a default pile and was used as a reference). The study took place over 137 days and three samples were taken (start, middle, end) and analyzed for aromatic and aliphatic compounds. The result of this study shows that there is a significant difference between all methods for the aliphatic compounds and no significant difference for the aromatic compounds. The abiotic factors that affect decomposition vary from organism to organism, depending on what type of environment it will function the best. In this type of environment it could be necessary to change temperature interval, nutrient availability or pH to optimize the conditions for the microorganisms. The conclusion of this report is that the structured of the soil-piles will affect decomposition rate, but it is unsure how much. Further research is needed to conclude how the soil should be structured to maximize the decomposition-rate.

Made available in DSpace on 2014-06-11T19:32:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-05Bitstream added on 2014-06-13T20:44:16Z : No. of bitstreams: 1 silveira_gg_dr_rcla.pdf: 641894 bytes, checksum: 52f7995780eb514330fda7bbbcb68b69 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Neste trabalho foi estudada a produção de renina microbiana pelo zigomiceto Mucor miehei utilizando Fermentação em Estado Sólido (FES). Os substratos utilizados foram farelos de trigo, laranja, aveia e arroz, bagaço de cana e casca de café. Foi estudada também a combinação de várias quantidades de dois substratos diferentes já mencionados. Dos substratos utilizados, não houve crescimento evidenciado do fungo quando foi utilizado, casca de café, bagaço de cana e farelo de laranja. Caseína é um importante fator na potencialização da biosíntese de renina tanto em fermentação submersa quanto em Fermentação em Estado Sólido. Nos experimentos com farelos de trigo e aveia as maiores atividades enzimáticas foram observadas entre 48 e 72 horas de cultivo, umidade acima de 79% e o aumento da quantidade de farelo de trigo na mistura foi favorável no que diz respeito ao aumento desta atividade. Nos experimentos com farelos de trigo e arroz sem suplementação de caseína, todas as combinações de meio de cultivo foram estatisticamente significativas sobre a atividade enzimática. Umidades acima de 98 % parecem inibir o crescimento do fungo e, consequentemente, a síntese enzimática que aumentou após 48 horas de cultivo. Quando houve a suplementação de caseína nos experimentos com farelos de trigo e arroz, houve um sensível incremento nas atividades enzimáticas. Os meios 2, 3 e 4 não forneceram influência estatisticamente importantes segundo o teste de Tukey e as menores atividades foram observadas no meio tipo 1. Umidades abaixo de 80 % e acima de 100 % forneceram baixas atividades enzimáticas. Assim como nos experimentos anteriores, as maiores atividades foram observadas após 48 horas de cultivo. Analisando-se todos os experimentos, verifica-se que as maiores atividades enzimáticas foram superiores quando comparadas aos relatos de outros pesquisadores. / The microbial rennin production by zigomiceto Mucor miehei produced on Solid State Fermentation (SSF) using wheat bran, rice bran, oat bran, sugarcane bagasse and coffee husk was studied in this work. The combination of two different substrates was also studied. No growth of microorganism was observed when coffee husk, sugar cane bagasse and orange pulp were used. Casein has an important factor in the rennin biosynthesis induction in Submerged Fermentation and Solid State Fermentation. In the experiments with wheat bran and oat bran the maximum enzyme activities had been observed between 48 and 72 hours. Moisture above of 79% and the wheat bran increase in the mixture were favorable for increase enzyme activity. Moisture above 98 % can inhibit the microorganism growth and the enzyme synthesis increased after 48 hours. When casein was added in wheat bran and rice bran medium, a rise in the enzymatic activities was observed. Low enzyme activities were observed in moisture between 80 % and 100 %. The highest activity was observed after 48 hours. The enzyme activity in this study was upper when compared with other researchers.

Biosignatures have been extensively studied at hot springs sites, such as Yellowstone, because liquid water is fundamental to the existence of life but also owing to the influx of mineral nutrients in these environments. However, some hot springs have upper temperatures exceeding the boundaries capable of sustaining life in all the spring facies, particularly those nearest the vent. Cold springs provide the same nutrient-rich environment with more ambient temperatures potentially capable of sustaining a diverse consortium of microorganisms across the entirety of the system. Ten Mile Graben Cold Springs, located in Southern Utah, is one such site known for its biota and preservation potential. This study aimed to observe the possible effects of the microorganisms on aragonite and calcite precipitation. Scanning electron microscope imagery observed biogenic fabric such as botryoidal aragonite and aragonite microspheres; however, the δ13C enrichment values of +2.80‰ to +7.30‰ imply the springs were dominantly precipitated through CO2 degassing. This discrepancy in the chemical and morphological data has been observed at other astrobiology analog sites such as Yellowstone; therefore, travertine and tufa seemingly do not preserve isotopic chemical biosignatures.