Browsing by Subject "Cyanobacteria"

Now showing 1 - 3 of 3
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    Experimental evolution of increased size and complexity in Anabaena variabilis
    (2014-05) Jacobsen, Kristin Alexa
    The evolution of multicellularity has occurred over 25 times in the history of life. Previously, we have shown the evolution of multicellular traits can readily be observed in laboratory populations across model unicellular organisms like yeast, chlamydomonas, and E. coli. Cyanobacteria are the oldest multicellular organisms, dating back 3.5 billion years. Many species appear morphologically unchanged, suggesting they have remained primitively multicellular. Are they incapable of evolving increased complexity? Model prokaryote Anabaena is a filamentous cyanobacteria, predating fossil records, existing as single strands or loose mats with three distinct cells types. Rapid settling was used to select for increased size advantage. Response to selection resulted in dramatic size increase; microscopic strands became inseparable macroscopic aggregates. Anabaena also became more complex; growth rate increased, two distinguishable morphologies developed, and growth and reproduction patterns changed. This shows that Anabaena, although primitively multicellular for billions of years, rapidly evolves increased size and complexity.
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    The intersection of climate change, watershed influence, and phytoplankton dynamics in Lake Superior
    (2021-06) Reinl, Kaitlin
    Climate change is leading to ecological shifts in lakes including altered thermal regimes, nutrient cycles, and food web structure. I explore how climate change is impacting phytoplankton dynamics in Lake Superior. I show that there are clear seasonal patterns in the development and degradation of the deep chlorophyll layer (DCL) and that as water temperatures warm there is a restructuring of the DCL, with a smaller thickness and greater maximum concentration at warmer temperatures. My research also shows that biological loading from rivers to Lake Superior may be an important source of seed populations for cyanobacterial blooms, particularly those characterized by low water temperature and high conductivity. Finally, I present a life cycle model to predict cyanobacterial blooms that integrates monitoring data and cyanobacteria life cycle stages. The model highlights the importance of phosphorus loading in promoting blooms and shows that akinete production may result in a decrease in peak summer vegetative biomass. This work lays the critical groundwork for understanding the impact of climate change on phytoplankton dynamics and their ecological implications.
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    Understanding Cyanobacteria-based Biofertilizers in Soil-Water and Soil-Plant Systems
    (2021-10) Alvarez De La Hoz, Adriana
    Growing pressures to increase agricultural productivity amid rising environmental impacts and global climate threats call for critical strategies that preserve the soil resource and improve sustainability. Microalgae, including cyanobacteria, are emerging as promising platforms to enhance soil structure and fertility and reduce our reliance on chemical fertilizers. To advance applications, further understanding is needed with different strains, plants, agroecological regions and types of soil including Mollisols, which are among the most productive soils in the world. This dissertation reviewed aspects of microalgae that might be applied in agriculture and evaluated effects of soil inoculations with the dinitrogen (N2)-fixing cyanobacterium Anabaena cylindrica UTEX 1611 on a Mollisol from the U.S. Upper Midwest. First, a comprehensive literature review supported microalgae as renewable resources for the potential development of biofertilizers, organic fertilizers, biostimulants, biocontrol agents, and soil conditioners. Furthermore, experiments with cyanobacterial soil inoculations described effects on soil structure and nutrient dynamics, soil loss and water nutrient levels after high-intensity rain simulations, and soil mineralization of cyanobacterial biomass. The results revealed changes in soil structural components that might be resistant to wind and water erosion, potential for reducing rainfall-induced soil loss, and a gradual nutrient release from the cyanobacterial biomass. High-intensity rain simulations also indicated depth-related positive changes in soil microbial dynamics that persisted after consecutive rains. Finally, experiments with a local variety of spring wheat consistently evidenced improvements in soil nutrients, microbial biomass, and microbial activity, and demonstrated that cyanobacteria, and a mixture with a local green microalga, supplied nitrogen (N) to support plant growth and partially replace urea. These findings provide insights on the positive role cyanobacteria might have as resources to enhance the sustainability and resiliency of agricultural systems.