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Spatial and Temporal Investigation of Microbial-Scale Interactions that Control Marine Sulfur Cycling.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	Spatial and Temporal Investigation of Microbial-Scale Interactions that Control Marine Sulfur Cycling./
作者:	O'Brien, James.
面頁冊數:	1 online resource (268 pages)
附註:	Source: Dissertations Abstracts International, Volume: 85-01, Section: B.
Contained By:	Dissertations Abstracts International85-01B.
標題:	Chemical oceanography. -
電子資源:	click for full text (PQDT)
ISBN:	9798379784409

Spatial and Temporal Investigation of Microbial-Scale Interactions that Control Marine Sulfur Cycling.
O'Brien, James.

Spatial and Temporal Investigation of Microbial-Scale Interactions that Control Marine Sulfur Cycling. - 1 online resource (268 pages)

Source: Dissertations Abstracts International, Volume: 85-01, Section: B.

Thesis (Ph.D.)--University of Technology Sydney (Australia), 2022.

Includes bibliographical references

Organosulfur molecules play critical roles in the ocean food-web and climate cycles. Perhaps the most important organosulfur compound in the ocean is dimethylsulfoniopropionate (DMSP), which is a precursor to dimethylsulfide (DMS) - the largest biogenic source of sulfur in Earth's atmosphere. DMSP is produced by phytoplankton and some bacteria. DMS(P) is cycled by these two groups via a multitude of catabolic pathways that are well characterised in the laboratory, but how these pathways control DMS(P) concentrations over space and time is still poorly understood. This thesis aimed to improve our understanding of the underlying ecology that determines DMS(P) concentrations in marine surface waters - by investigating how microbial communities coincide with (1) in situ DMS(P) concentrations, and (2) genes encoding biogeochemical transformations, including DMS(P) degradation pathways. This was achieved by using biogeochemical, environmental and molecular data obtained from an oceanic research voyage and a network of pelagic time-series located around the Australian continent. A 30° transect in the east Indian Ocean revealed novel biogeographic communities that possess distinct microbial assemblages and functional genes encoding carbon, nitrogen and sulfur transformations. Along this transect was a surprising trend of greater DMSP in low latitudes compared to high latitudes, along with significant spatial variability in the abundance of genes encoding bacterial DMSP production and degradation. The microbial ecology underlying temporal shifts in DMS(P) was investigated during a two-year time-series on the east Australian coastline. DMS(P) demonstrated seasonal increases and exhibited strong temporal relationships with phytoplankton from predicted high DMSP producing lineages (HiDP); the heterotrophic bacteria, Rhodobacterales and their associated DMSP degradation genes - suggesting a dependence of phytoplankton-derived DMSP for the bacterial group. This relationship (between HiDP and Rhodobacterales) was explored across a network of seven coastal time-series around the Australian continent. A clade of Rhodobacterales, the marine Roseobacter group (MRG) demonstrated tighter spatial and temporal coupling with HiDPs compared with other phytoplankton-bacteria relationships. Among these relationships were known model relationships and several novel ecological associations, including new evidence of relationships between HiDP picoeukaryotes and MRGs. Overall, the findings of this thesis have advanced our understanding of the microbial ecology driving spatiotemporal variation in DMS(P) cycles by providing evidence of unexpected DMSP cycling dynamics in the Indian Ocean region and novel interkingdom relationships that may have profound implications for the ocean sulfur cycle - which ultimately deserve further investigation to determine their biogeochemical importance.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798379784409Subjects--Topical Terms:

642003
Chemical oceanography.
Index Terms--Genre/Form:

554714
Electronic books.

Spatial and Temporal Investigation of Microbial-Scale Interactions that Control Marine Sulfur Cycling.
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520 $a Organosulfur molecules play critical roles in the ocean food-web and climate cycles. Perhaps the most important organosulfur compound in the ocean is dimethylsulfoniopropionate (DMSP), which is a precursor to dimethylsulfide (DMS) - the largest biogenic source of sulfur in Earth's atmosphere. DMSP is produced by phytoplankton and some bacteria. DMS(P) is cycled by these two groups via a multitude of catabolic pathways that are well characterised in the laboratory, but how these pathways control DMS(P) concentrations over space and time is still poorly understood. This thesis aimed to improve our understanding of the underlying ecology that determines DMS(P) concentrations in marine surface waters - by investigating how microbial communities coincide with (1) in situ DMS(P) concentrations, and (2) genes encoding biogeochemical transformations, including DMS(P) degradation pathways. This was achieved by using biogeochemical, environmental and molecular data obtained from an oceanic research voyage and a network of pelagic time-series located around the Australian continent. A 30° transect in the east Indian Ocean revealed novel biogeographic communities that possess distinct microbial assemblages and functional genes encoding carbon, nitrogen and sulfur transformations. Along this transect was a surprising trend of greater DMSP in low latitudes compared to high latitudes, along with significant spatial variability in the abundance of genes encoding bacterial DMSP production and degradation. The microbial ecology underlying temporal shifts in DMS(P) was investigated during a two-year time-series on the east Australian coastline. DMS(P) demonstrated seasonal increases and exhibited strong temporal relationships with phytoplankton from predicted high DMSP producing lineages (HiDP); the heterotrophic bacteria, Rhodobacterales and their associated DMSP degradation genes - suggesting a dependence of phytoplankton-derived DMSP for the bacterial group. This relationship (between HiDP and Rhodobacterales) was explored across a network of seven coastal time-series around the Australian continent. A clade of Rhodobacterales, the marine Roseobacter group (MRG) demonstrated tighter spatial and temporal coupling with HiDPs compared with other phytoplankton-bacteria relationships. Among these relationships were known model relationships and several novel ecological associations, including new evidence of relationships between HiDP picoeukaryotes and MRGs. Overall, the findings of this thesis have advanced our understanding of the microbial ecology driving spatiotemporal variation in DMS(P) cycles by providing evidence of unexpected DMSP cycling dynamics in the Indian Ocean region and novel interkingdom relationships that may have profound implications for the ocean sulfur cycle - which ultimately deserve further investigation to determine their biogeochemical importance.
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