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The Effects of Climate Change Processes and Eutrophication on Nostocales: An N2 Fixing, Bloom-Forming, Toxin-Producing Cyanobacterial Order.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	The Effects of Climate Change Processes and Eutrophication on Nostocales: An N2 Fixing, Bloom-Forming, Toxin-Producing Cyanobacterial Order./
作者:	Kramer, Benjamin James.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2022,
面頁冊數:	349 p.
附註:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
標題:	Microbiology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29212182
ISBN:	9798834072751

The Effects of Climate Change Processes and Eutrophication on Nostocales: An N2 Fixing, Bloom-Forming, Toxin-Producing Cyanobacterial Order.
Kramer, Benjamin James.

The Effects of Climate Change Processes and Eutrophication on Nostocales: An N2 Fixing, Bloom-Forming, Toxin-Producing Cyanobacterial Order. - Ann Arbor : ProQuest Dissertations & Theses, 2022 - 349 p.

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Ph.D.)--State University of New York at Stony Brook, 2022.

This item must not be sold to any third party vendors.

Nostocales are diazotrophic (N2 fixing) cyanobacteria that form toxin-producing blooms in freshwater and brackish ecosystems. Some species of this order have also expanded from tropical to temperate latitudes in the last few decades, purportedly due to climatic warming. As the conditions required for Nostocales to thrive under warming scenarios are poorly understood, my dissertation characterizes how fixed N and changing levels of CO2 affect N2 fixation, growth rate, and toxin production of Nostocales, primarily those of the genus Dolichospermum. Physiological and transcriptomic analyses of an anatoxin-producing Dolichospermum strain indicated that urea and NH4+ were preferred N sources for optimal growth rates that significantly suppressed N2 fixation, toxin quotas, and expression of genes which encode subunits of nitrogenase (nif) and anatoxin synthetase (ana). NO3--grown cultures also exhibited significantly lower growth rates and higher N2 fixation rates and anatoxin-a quotas than NH4+-grown cultures. This indicates that Dolichospermum used NO3- assimilation and nitrogenase activity simultaneously to meet cellular N demands. This dissertation also investigated the effects of NO3- availability and CO2 enrichment on anatoxin, microcystin, and saxitoxin - producing strains of Dolichospermum. Growth rates of all Dolichospermum spp. significantly increased with elevated CO2 or both CO2 and NO3-, while the N2 fixation rates of NO3--amended, CO2-enriched cultures were significantly higher relative to NO3--amended cultures grown under ambient CO2 conditions. Cellular quotas of N-rich microcystins and saxitoxins significantly declined, while quotas of the N-poor anatoxin significantly increased under CO2 enrichment. This dissertation also investigated how these same Dolichospermum strains and cyanobacterial communities comprised of Nostocales were affected by simulated heat waves and fixed N. Temperatures >26℃ significantly reduced the growth rates of the anatoxin and microcystin - producing Dolichospermum strains isolated from polar lakes, while the saxitoxin producer isolated from sub-tropical latitudes thrived under the same temperature regime. All strains also exhibited significantly reduced N2 fixation rates when grown under higher (29 - 30℃) relative to lower (13 - 26℃) temperatures. The N2 fixation rates of cyanobacterial communities collected from several New York lakes similarly declined in response to heat wave-mimicking temperature patterns despite growth rates increasing significantly under warming and when amended with NH4+. Collectively, these results indicate that heat waves will cause significant reductions in cyanobacterial diazotrophy in freshwater ecosystems, an outcome that will have important biogeochemical implications. Lastly, the effects of CO2 enrichment, elevated temperature, as well as NH4+ and PO43- amendment on cyanobacterial (16S) and diazotrophic (nifH) communities from a shallow, eutrophic freshwater lake were quantified. The biomass of Nostocales within 16S and nifH communities significantly increased in response to CO2 enrichment and NH4+ amendment as well as under elevated CO2 and temperature conditions, indicating that Nostocales and N2 fixation may increase in CO2-enriched eutrophic lentic systems experiencing heat waves. Moreover, the N2 fixation rates of Nostocales grown under CO2 and NH4+ - enriched conditions were significantly higher than those of Nostocales amended with NH4+ and grown under ambient CO2 conditions. Collectively, this research provides novel insights with respect to the response of cyanobacterial diazotrophs to changes in temperature, CO2, and nutrients, and indicates that Nostocales will thrive in eutrophic systems that are subjected to warming and/or CO2 enrichment.

ISBN: 9798834072751Subjects--Topical Terms:

536250
Microbiology.
Subjects--Index Terms:

Carbon dioxide

The Effects of Climate Change Processes and Eutrophication on Nostocales: An N2 Fixing, Bloom-Forming, Toxin-Producing Cyanobacterial Order.
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300 $a 349 p.
500 $a Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
500 $a Advisor: Gobler, Christopher J.
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520 $a Nostocales are diazotrophic (N2 fixing) cyanobacteria that form toxin-producing blooms in freshwater and brackish ecosystems. Some species of this order have also expanded from tropical to temperate latitudes in the last few decades, purportedly due to climatic warming. As the conditions required for Nostocales to thrive under warming scenarios are poorly understood, my dissertation characterizes how fixed N and changing levels of CO2 affect N2 fixation, growth rate, and toxin production of Nostocales, primarily those of the genus Dolichospermum. Physiological and transcriptomic analyses of an anatoxin-producing Dolichospermum strain indicated that urea and NH4+ were preferred N sources for optimal growth rates that significantly suppressed N2 fixation, toxin quotas, and expression of genes which encode subunits of nitrogenase (nif) and anatoxin synthetase (ana). NO3--grown cultures also exhibited significantly lower growth rates and higher N2 fixation rates and anatoxin-a quotas than NH4+-grown cultures. This indicates that Dolichospermum used NO3- assimilation and nitrogenase activity simultaneously to meet cellular N demands. This dissertation also investigated the effects of NO3- availability and CO2 enrichment on anatoxin, microcystin, and saxitoxin - producing strains of Dolichospermum. Growth rates of all Dolichospermum spp. significantly increased with elevated CO2 or both CO2 and NO3-, while the N2 fixation rates of NO3--amended, CO2-enriched cultures were significantly higher relative to NO3--amended cultures grown under ambient CO2 conditions. Cellular quotas of N-rich microcystins and saxitoxins significantly declined, while quotas of the N-poor anatoxin significantly increased under CO2 enrichment. This dissertation also investigated how these same Dolichospermum strains and cyanobacterial communities comprised of Nostocales were affected by simulated heat waves and fixed N. Temperatures >26℃ significantly reduced the growth rates of the anatoxin and microcystin - producing Dolichospermum strains isolated from polar lakes, while the saxitoxin producer isolated from sub-tropical latitudes thrived under the same temperature regime. All strains also exhibited significantly reduced N2 fixation rates when grown under higher (29 - 30℃) relative to lower (13 - 26℃) temperatures. The N2 fixation rates of cyanobacterial communities collected from several New York lakes similarly declined in response to heat wave-mimicking temperature patterns despite growth rates increasing significantly under warming and when amended with NH4+. Collectively, these results indicate that heat waves will cause significant reductions in cyanobacterial diazotrophy in freshwater ecosystems, an outcome that will have important biogeochemical implications. Lastly, the effects of CO2 enrichment, elevated temperature, as well as NH4+ and PO43- amendment on cyanobacterial (16S) and diazotrophic (nifH) communities from a shallow, eutrophic freshwater lake were quantified. The biomass of Nostocales within 16S and nifH communities significantly increased in response to CO2 enrichment and NH4+ amendment as well as under elevated CO2 and temperature conditions, indicating that Nostocales and N2 fixation may increase in CO2-enriched eutrophic lentic systems experiencing heat waves. Moreover, the N2 fixation rates of Nostocales grown under CO2 and NH4+ - enriched conditions were significantly higher than those of Nostocales amended with NH4+ and grown under ambient CO2 conditions. Collectively, this research provides novel insights with respect to the response of cyanobacterial diazotrophs to changes in temperature, CO2, and nutrients, and indicates that Nostocales will thrive in eutrophic systems that are subjected to warming and/or CO2 enrichment.
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653 $a Cyanobacteria
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653 $a Heat wave
653 $a Nitrogen fixation
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710 2 $a State University of New York at Stony Brook. $b Marine and Atmospheric Science. $3 1683777
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