Matching Items (3)
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- All Subjects: Biogeochemistry
- All Subjects: Archaebacteria
- All Subjects: carbon cycling
- Genre: Masters Thesis
- Creators: Cadillo-Quiroz, Hinsby
- Member of: Theses and Dissertations
Description
Peatlands represent 3% of the earth’s surface but have been estimated to contain up to 30% of all terrestrial soil organic carbon and release an estimated 40% of global atmospheric CH4 emissions. Contributors to the production of CH4 are methanogenic Archaea through a coupled metabolic dependency of end products released by heterotrophic bacteria within the soil in the absence of O2. To better understand how neighboring bacterial communities can influence methanogenesis, the isolation and physiological characterization of two novel isolates, one Methanoarchaeal isolate and one Acidobacterium isolate identified as QU12MR and R28S, respectively, were targeted in this present study. Co-culture growth in varying temperatures of the QU12MR isolate paired with an isolated Clostridium species labeled R32Q and the R28S isolate were also investigated for possible influences in CH4 production. Phylogenetic analysis of strain QU12MR was observed as a member of genus Methanobacterium sharing 98% identity similar to M. arcticum strain M2 and 99% identity similar to M. uliginosum strain P2St. Phylogenetic analysis of strain R28S was associated with genus Acidicapsa from the phylum Acidobacteria, sharing 97% identity to A. acidisoli strain SK-11 and 96% identity similarity to Occallatibacter savannae strain A2-1c. Bacterial co-culture growth and archaeal CH4 production was present in the five temperature ranges tested. However, bacterial growth and archaeal CH4 production was less than what was observed in pure culture analysis after 21 days of incubation.
ContributorsRamirez, Zeni Elizia (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Roberson, Robert (Thesis advisor) / Wang, Xuan (Committee member) / Arizona State University (Publisher)
Created2018
Description
Utilizing both 16S and 18S rRNA sequencing alongside energetic calculations from geochemical measurements offers a bridged perspective of prokaryotic and eukaryotic community diversities and their relationships to geochemical diversity. Yellowstone National Park hot spring outflows from varied geochemical compositions, ranging in pH from < 2 to > 9 and in temperature from < 30°C to > 90°C, were sampled across the photosynthetic fringe, a transition in these outflows from exclusively chemosynthetic microbial communities to those that include photosynthesis. Illumina sequencing was performed to document the diversity of both prokaryotes and eukaryotes above, at, and below the photosynthetic fringe of twelve hot spring systems. Additionally, field measurements of dissolved oxygen, ferrous iron, and total sulfide were combined with laboratory analyses of sulfate, nitrate, total ammonium, dissolved inorganic carbon, dissolved methane, dissolved hydrogen, and dissolved carbon monoxide were used to calculate the available energy from 58 potential metabolisms. Results were ranked to identify those that yield the most energy according to the geochemical conditions of each system. Of the 46 samples taken across twelve systems, all showed the greatest energy yields using oxygen as the main electron acceptor, followed by nitrate. On the other hand, ammonium or ammonia, depending on pH, showed the greatest energy yields as an electron donor, followed by H2S or HS-. While some sequenced taxa reflect potential biotic participants in the sulfur cycle of these hot spring systems, many sample locations that yield the most energy from ammonium/ammonia oxidation have low relative abundances of known ammonium/ammonia oxidizers, indicating potentially untapped sources of chemotrophic energy or perhaps poorly understood metabolic capabilities of cultured chemotrophs.
ContributorsRomero, Joseph Thomas (Author) / Shock, Everett L (Thesis advisor) / Cadillo-Quiroz, Hinsby (Committee member) / Till, Christy B. (Committee member) / Arizona State University (Publisher)
Created2018
Description
Soil organic carbon (SOC) is a critical component of the global carbon (C) cycle, accounting for more C than the biotic and atmospheric pools combined. Microbes play an important role in soil C cycling, with abiotic conditions such as soil moisture and temperature governing microbial activity and subsequent soil C processes. Predictions for future climate include warmer temperatures and altered precipitation regimes, suggesting impacts on future soil C cycling. However, it is uncertain how soil microbial communities and subsequent soil organic carbon pools will respond to these changes, particularly in dryland ecosystems. A knowledge gap exists in soil microbial community responses to short- versus long-term precipitation alteration in dryland systems. Assessing soil C cycle processes and microbial community responses under current and altered precipitation patterns will aid in understanding how C pools and cycling might be altered by climate change. This study investigates how soil microbial communities are influenced by established climate regimes and extreme changes in short-term precipitation patterns across a 1000 m elevation gradient in northern Arizona, where precipitation increases with elevation. Precipitation was manipulated (50% addition and 50% exclusion of ambient rainfall) for two summer rainy seasons at five sites across the elevation gradient. In situ and ex situ soil CO2 flux, microbial biomass C, extracellular enzyme activity, and SOC were measured in precipitation treatments in all sites. Soil CO2 flux, microbial biomass C, extracellular enzyme activity, and SOC were highest at the three highest elevation sites compared to the two lowest elevation sites. Within sites, precipitation treatments did not change microbial biomass C, extracellular enzyme activity, and SOC. Soil CO2 flux was greater under precipitation addition treatments than exclusion treatments at both the highest elevation site and second lowest elevation site. Ex situ respiration differed among the precipitation treatments only at the lowest elevation site, where respiration was enhanced in the precipitation addition plots. These results suggest soil C cycling will respond to long-term changes in precipitation, but pools and fluxes of carbon will likely show site-specific sensitivities to short-term precipitation patterns that are also expected with climate change.
ContributorsMonus, Brittney (Author) / Throop, Heather L (Thesis advisor) / Ball, Becky A (Committee member) / Hultine, Kevin R (Committee member) / Munson, Seth M (Committee member) / Arizona State University (Publisher)
Created2019