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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Ocorrência de leveduras pertencentes ao gênero Cryptococcus em cloaca e inglúvio de papagaios do gênero Amazona aestiva. / Occurrence of yeast belonging to the genus Cryptococcus in cloaca and crop of parrots of the genus Amazona aestiva.

Diana Costa Nascimento 18 April 2013 (has links)
Realizamos o isolamento de leveduras do complexo Cryptococcus a partir da cloaca e do inglúvio de papagaios do gênero Amazona aestiva. Para a realização das coletas, as aves foram anestesiadas, e em seguida foi realizado lavado do inglúvio e coleta de material da cloaca. As amostras coletadas foram inoculadas em ágar Sabouraud dextrose com cloranfenicol, de onde foram isoladas colônias leveduriformes. Por meio de análises macro e micromorfológicas, os isolados condizentes com as características do gênero Cryptococcus foram submetidos à provas bioquímicas, testes de suscetibilidade aos antifúngicos e pesquisa de exoenzimas. Todos os isolados foram provenientes da cloaca. Dos isolamentos, 90% das cepas corresponderam à espécie C. albidus, e 10% à espécie C. laurentii; 80% foram produtores de fosfolipase e 100% de proteinase. Estes resultados sugerem que não só o ambiente, como também as aves podem ser carreadoras de Cryptococcus albidus. / We performed the isolation of yeasts of Cryptococcus complex from the cloaca and the crop of parrots of the genus Amazona aestiva. To carry out the sampling, the birds were anesthetized to perform a lavage of the crop and the collection of material from the cloaca. The samples were inoculated on Sabouraud dextrose agar with chloramphenicol, which were isolated from yeast colonies. Through macro and micromorphological analysis, isolates consistent with the characteristics of the genus Cryptococcus were subjected to biochemical tests, antifungal susceptibility testing and research exoenzymes. All isolates were from the cloaca. Of the isolates, 90% of the strains corresponded to the species C. albidus, and 10% of the species C. laurentii; 80% of the isolates were producing phospholipase and 100% were producing proteinase. These results suggest that not only environmental but also birds can be Cryptococcus albidus carrier. These results suggest that there is not only an environmental source but also birds can be Cryptococcus albidus carriers
112

STUDIES RELATING PQQ BIOSYNTHESIS TO PUTATIVE PEPTIDASES AND OPERON STRUCTURE IN <em>PSEUDOMONAS</em> SPECIES

Diaz, Benjamin 01 January 2017 (has links)
Several bacteria isolated from the broccoli rhizosphere were assayed to compare their ability to solubilize phosphate and release pyrroloquinoline quinone (PQQ) into the surrounding media. Subsequently, their genomes were sequenced and analyzed for PQQ biosynthesis operon structure. PQQ biosynthesis genes pqqA-F were found in all isolates. The order of PQQ biosynthesis genes and predicted amino acid sequences were compared to each other and the host’s ability to solubilize phosphate and release PQQ. In all Pseudomonas species, two putative protease genes, pqqF, and pqqG, flanked the canonical pqqA-pqqE biosynthesis operon. No mechanistic studies have confirmed the function of pqqF and pqqG. Pseudomonas putida KT2440 is a versatile model organism, representing environmental, agronomical, and industrial interests. Like the broccoli isolates, P. putida KT2440 biosynthesizes and releases PQQ into its surroundings. To better understand their functions within PQQ synthesis in P. putida KT2440, ∆pqqF, ∆pqqG, and ∆pqqF/∆pqqG strains of P. putida KT2440 were generated and the resulting phenotypes were studied.
113

Controls on Benthic Microbial Community Structure and Assembly in a Karstic Coastal Wetland

Schulte, Nicholas O 31 March 2016 (has links)
The assembly mechanisms underlying microbial community abundance, biotic interactions, and diversity over space and time are unresolved, particularly in benthic microbial mats distributed along environmental gradients. Experimental enrichment of nutrient-limited microbial mats from the Florida Everglades along a nutrient subsidy-salinity stress gradient stimulated autotrophic and heterotrophic metabolism, growth, and diversity independent of autotroph-heterotroph interactions across treatments and space. These results suggest spatial segregation of autotrophic and heterotrophic components within mats. Considering only the diatom component of Everglades mats over space and time, the subsidy-stress gradient controlled diatom compositional turnover at broad spatial scales while environmental and dispersal-based processes structured diatom communities at the regional scale and environmental processes independent of the environmental gradient at the temporal scale. These results indicate environmental gradients may not necessarily increase connectivity and dispersal across space, and temporal microbial diversity is driven at the local and regional scales by environmental heterogeneity in benthic microbial communities.
114

Changing Bacterial Growth Efficiencies across a Natural Nutrient Gradient in an Oligotrophic Estuary

Kiger, Amber A 27 March 2015 (has links)
Recent studies have characterized coastal estuarine systems as important components of the global carbon cycle. This study investigated carbon cycling through the microbial loop of Florida Bay by use of bacterial growth efficiency calculations. Bacterial production, bacterial respiration, and other environmental parameters were measured at three sites located along a historic phosphorus-limitation gradient in Florida Bay and compared to a relatively nutrient enriched site in Biscayne Bay. A new method for measuring bacterial respiration in oligotrophic waters involving tracing respiration of 13C-glucose was developed. The results of the study indicate that 13C tracer assays may provide a better means of measuring bacterial respiration in low nutrient environments than traditional dissolved oxygen consumption-based methods due to strong correlations between incubation length and δ13C values. Results also suggest that overall bacterial growth efficiency may be lower at the most nutrient limited sites.
115

A Study on the Dissolution of Autunite Minerals by Facultative Bacteria in Bicarbonate Media

Herrera Landaez, Sandra C. 01 April 2016 (has links)
Uranium (U) is a key contaminant at the Hanford site. The formation of uranyl-phosphate bearing minerals such as autunite as a result of tripoliphosphate injections has been used as a U immobilization strategy. Bacteria are known as key factors governing the fate and transport of soil contaminants. This research evaluated the interaction of facultative bacteria Shewanella Oneidensis MR-1 with autunite mineral in bicarbonate-amended media solutions. The concentration of several elements such as U, calcium (Ca) and phosphorous (P) released as a result of autunite mineral biodissolution were determined as a function of time; changes in cell density and protein assay were performed to evaluate cells viability. Results suggested that higher bicarbonate concentrations increased aqueous U, Ca and P concentrations while also allowing cells to withstand U toxicity and, additionally suggested the possibility of secondary minerals formation. This research provides a better understanding on the stability of uranyl phosphate minerals in the presence of facultative bacteria in bicarbonate-amended media solutions.
116

Metagenômica comparativa e perfil metabólico in silico de solos no município de Cubatão, SP. / Comparative metagenomics and metabolic soil profiling in Cubatão County, SP.

Bruno Karolski 19 June 2013 (has links)
Cubatão, o maior pólo industrial da américa latina também já foi uma das cidades mais poluídas do mundo. Os 30 anos de intensa atividade industrial vêm pressionando o meio ambiente com substâncias tóxicas e afetando gravemente a saúde da população. Dentre as substâncias contaminantes mais importantes da região estão os derivados de petróleo como o benzeno, tolueno, etilbenzeno e xilenos. Conhecidos como BTEX, eles são produzidos e utilizados em larga escala e a contaminação ocorre frequentemente através de vazamentos. Nos solos, devido à sua solubilidade em água, essas substâncias podem se espalhar por longas distâncias a partir do ponto afetado contaminando locais distantes. Já foi comprovada a capacidade de micro-organismos de sobreviver e até utilizar BTEX como fonte de carbono. Os micro-organismos adaptados catabolizam os contaminantes transformando-os em substâncias menos tóxicas e até mesmo eliminando-os do ambiente, capacidade de grande interesse econômico e ambiental. Nessa linha, nossa proposta visa o estudo das comunidades microbianas de solos afetados e não afetados por BTEX. Para isso foi utilizada a metagenômica como abordagem de estudo identificando-se diferenças qualitativas e quantitativas nas estruturas microbianas de três diferentes locais do município de Cubatão, sendo um deles afetado diretamente por BTEX. Pelo método utilizado e aqui desenvolvido, foi possível identificar um panorama metabólico geral identificando-se genes relevantes e o potencial de degradação de hidrocarbonetos aromáticos de micro-organismos conhecidos e desconhecidos, revelando melhor o potencial metabólico dos solos identificados. Os resultados apresentados podem contribuir para um melhor entendimento da dinâmica in situ de uma comunidade microbiana afetada por BTEX assim como melhorar o conhecimento sobre a comunidade microbiana de um local altamente impactado como Cubatão. / Cubatão is the largest industrial site in Latin America and was in the past one of the most polluted cities in the world. 30 years of intense industrial activity has pushed environmental limits with toxic substances and has severely affected the inhabitants\' health. Among the contaminants found in the region, the petroleum derivatives benzene, toluene, ethylbenzene and xylenes are the most important. Known collectively as BTEX, they are produced and used at a large scale and contamination frequently occurs. Because it is highly soluble in water, when in soil BTEX can spread long distances from the original contamination site, thus affecting large areas. Some microorganisms are known to live in contaminated environments and use contaminants such as BTEX as a unique carbon source for energy production. They catabolize contaminants into less dangerous products or even eliminate them from environment, a feature which has great commercial and environmental interest. We therefore compared the microbial communities in soils which were affected and un-affected by BTEX contamination. To this end, we used a metagenomics approach and developed a comparison method to identify microorganisms and degradation potential of soils studied. We found qualitative and quantitative differences in microbial structures from three different sites in Cubatão County, one of which is contaminated with BTEX. We constructed a metabolic overview identifying important genes, degradation potential and microorganisms related to BTEX degradation. The results presented here could contribute to understanding the in situ dynamics of a BTEX affected microbial community as well as improving our knowledge of the microbial community of Cubatão, a highly environmentally impacted place.
117

The Effects of Water Quality Changes Due to Highway Construction on Aquatic Insects as Measured by the DHA-INT Assay

Craig, C. L., Scheuerman, Phillip R., Lanza, G. R., Farris, J. L. 01 January 1993 (has links)
No description available.
118

Effects of Initial Biomass Concentration on the Degradation of the Creosote Constituent m-Cresol

Black, T. E., Scheuerman, Phillip R., Lanza, G. R. 01 January 1995 (has links)
No description available.
119

Coliphages as Indicators of Fecal Pollution

Hamilton, K., Scheuerman, Phillip R. 01 January 1996 (has links)
No description available.
120

The Effect of Cell Inoculum Level and Substrate Concentration on p- cresol Degradation

Barrett, E., Scheuerman, Phillip R. 31 January 1998 (has links)
No description available.

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