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Full-Text Articles in Microbiology
Determining The Ecological And Physiological Factors Contributing To The Competitive Success Of Prochlorococcus In The Oligotrophic Ocean, Benjamin C. Calfee
Determining The Ecological And Physiological Factors Contributing To The Competitive Success Of Prochlorococcus In The Oligotrophic Ocean, Benjamin C. Calfee
Doctoral Dissertations
Prochlorococcus is a genus of extremely successful marine cyanobacteria. This success is realized through its pervasive biogeographical range and presence in almost all open ocean environments where it usually it the dominant phytoplankton. Limited capabilities of culturing and genetic manipulation of this organism have resulted in assumptions about this success overwhelmingly based on field observations. These studies have assumed adaptations for resource uptake and utilization in nutrient limited environments to cause dominance of Prochlorococcus over other photosynthetic microbes. In an attempt to definitively explain this through laboratory culture, we developed a culturing system to assay questions of nutrient limitation effects …
Environmentally Driven Orchestration Of Metabolisms By Prochlorococcus Spp., Martin James Szul
Environmentally Driven Orchestration Of Metabolisms By Prochlorococcus Spp., Martin James Szul
Doctoral Dissertations
In the oligotrophic waters of the world’s open oceans physical factors such as pH, salinity, and temperature are generally stable. The nutrient limited conditions as well as the low environmental variability endemic to these ecosystems select for specialists that gain fitness advantages through minimalism, efficiency, and thrift. These physical characteristics are thought to reduce nutrient demand while allowing for constant metabolic activity and growth, but the mechanisms that promote these fitness advantages are currently unknown. To better understand how these physiologies improve selective fitness for the dominant phytoplankton, we observed metabolic parameters under environmental conditions typical to these waters. In …
Physiological Characterization Of Prochlorococcus Under Abiotic Stressors Temperature And Hydrogen Peroxide, Lanying Ma
Physiological Characterization Of Prochlorococcus Under Abiotic Stressors Temperature And Hydrogen Peroxide, Lanying Ma
Doctoral Dissertations
Cyanobacteria of the genus Prochlorococcus are the smallest and most abundant phytoplankters in the ocean. Temperature is a major influence on Prochlorococcus abundance and distribution in the ocean, but the physiological basis for this relationship is not well understood. In other microbes, lipid and fatty acid composition have been shown to be influenced by temperature, and temperature has also been proposed as a relevant factor for setting the elemental allocation in marine phytoplankton. In this study, we found that percentage of fatty acids unsaturation was negatively related with temperature in some Prochlorococcus strains, but this was not universal. Temperature had …
Relationships Among Prochlorococcus Ecotypes Across Oceanic Temperature Ranges, Jeremy Werner Chandler
Relationships Among Prochlorococcus Ecotypes Across Oceanic Temperature Ranges, Jeremy Werner Chandler
Doctoral Dissertations
Prochlorococcus, the world’s smallest known photosynthetic organism, is an open ocean cyanobacterium, thought to be globally significant in nutrient cycling. Genetically and physiologically distinct “ecotypes” of Prochlorococcus populate the world’s subtropical and tropical oceans. A few of these key ecotypes comprise the majority of these populations, with the dominant ecotypes frequently varying as a function of depth and latitude. The mechanisms underlying the specific distributions of the ecotypes remain poorly understood, but temperature was believed to play a key role in latitudinal partitioning. Quantitative PCR (Q-PCR) was used to assess ecotypic abundances across transects spanning the Pacific Ocean from 27°N …
The ‘Helper’ Phenotype: A Symbiotic Interaction Between Prochlorococcus And Hydrogen Peroxide Scavenging Microorganisms, James Jeffrey Morris
The ‘Helper’ Phenotype: A Symbiotic Interaction Between Prochlorococcus And Hydrogen Peroxide Scavenging Microorganisms, James Jeffrey Morris
Doctoral Dissertations
The unicellular cyanobacterium Prochlorococcus is the numerically dominant photosynthetic organism throughout the temperate and tropical open oceans, but it is difficult to grow in pure cultures. We developed a system for rendering spontaneous streptomycin-resistant mutants of Prochlorococcus axenic by diluting them to extinction in the presence of “helper” heterotrophic bacteria, allowing them to grow to high cell concentrations, and then killing the helpers with streptomycin. Using axenic strains obtained in this fashion, we demonstrated that Prochlorococcus experiences a number of growth defects in dilute axenic culture, including reduced growth rate, inability to form colonies on solid media, and higher incidence …