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Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses./
Author:	Showalter, Gordon Maxwell.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
Description:	169 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-05, Section: B.
Contained By:	Dissertations Abstracts International82-05B.
Subject:	Microbiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28094797
ISBN:	9798684670848

Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses.
Showalter, Gordon Maxwell.

Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 169 p.

Source: Dissertations Abstracts International, Volume: 82-05, Section: B.

Thesis (Ph.D.)--University of Washington, 2020.

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

Marine dissolved organic carbon (DOC) is a major component of the global carbon pool, and thus can have significant effects on global carbon cycling. Within the oceans, DOC is largely regulated by microbial communities, which can serve as both a source and sink of organic carbon. Microbial controls on DOC cycling within sea ice are especially relevant to global processes, as sea ice can act as an inhibitor of exchange between the ocean and the atmosphere while also affecting carbon export to the deep sea. However, how sea-ice communities influence DOC cycling, especially in very cold conditions of winter sea ice, is poorly understood.This dissertation explores how bacterial communities, which dominate winter sea ice, may influence DOC cycling. Chapter 1 presents an introduction of sea-ice microbial communities in the low-temperature, high salinity conditions which characterize sea-ice brines. How bacteria within brines swim in response to temperature, salinity, and chemical gradients in sea ice is presented in Chapter 2, which demonstrates a low-temperature record for directed bacterial swimming and suggests explanations for how bacteria position themselves within brines to access DOC. However, most DOC within the marine environment is too large for bacterial uptake, necessitating degradation by enzymes. Chapter 3 demonstrates bacterial extracellular enzyme activity both in a laboratory setting and in situ, showing growth-dependent enzyme activity down to -8˚C and up to 142 ppt salts and across a freeze-thaw cycle within sea ice and sea-surface microlayer samples. Finally, Chapter 4 presents a model of bacterially and virally mediated DOC cycling. This model uses simple differential equations, explained further in Appendix 1, to probe the potential existence of a viral shunt within sea-ice brines by demonstrating the role of bacteriophage in population dynamics of a theoretical brine, suggesting low viral production, high host-specificity, and virally-driven DOC cycling may be common within this environment. The results of this dissertation have implications for the understanding of DOC within polar seas and demonstrate the potential for active DOC cycling mediated by bacteria and their viruses within winter sea ice, which serves as an analog for very cold ice elsewhere.

ISBN: 9798684670848Subjects--Topical Terms:

536250
Microbiology.
Subjects--Index Terms:

Bacteria

Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses.
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245 1 0 $a Acquisition, Degradation, and Cycling of Organic Matter Within Sea-Ice Brines by Bacteria and Their Viruses.
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300 $a 169 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-05, Section: B.
500 $a Advisor: Deming, Jody W.
502 $a Thesis (Ph.D.)--University of Washington, 2020.
506 $a This item must not be sold to any third party vendors.
520 $a Marine dissolved organic carbon (DOC) is a major component of the global carbon pool, and thus can have significant effects on global carbon cycling. Within the oceans, DOC is largely regulated by microbial communities, which can serve as both a source and sink of organic carbon. Microbial controls on DOC cycling within sea ice are especially relevant to global processes, as sea ice can act as an inhibitor of exchange between the ocean and the atmosphere while also affecting carbon export to the deep sea. However, how sea-ice communities influence DOC cycling, especially in very cold conditions of winter sea ice, is poorly understood.This dissertation explores how bacterial communities, which dominate winter sea ice, may influence DOC cycling. Chapter 1 presents an introduction of sea-ice microbial communities in the low-temperature, high salinity conditions which characterize sea-ice brines. How bacteria within brines swim in response to temperature, salinity, and chemical gradients in sea ice is presented in Chapter 2, which demonstrates a low-temperature record for directed bacterial swimming and suggests explanations for how bacteria position themselves within brines to access DOC. However, most DOC within the marine environment is too large for bacterial uptake, necessitating degradation by enzymes. Chapter 3 demonstrates bacterial extracellular enzyme activity both in a laboratory setting and in situ, showing growth-dependent enzyme activity down to -8˚C and up to 142 ppt salts and across a freeze-thaw cycle within sea ice and sea-surface microlayer samples. Finally, Chapter 4 presents a model of bacterially and virally mediated DOC cycling. This model uses simple differential equations, explained further in Appendix 1, to probe the potential existence of a viral shunt within sea-ice brines by demonstrating the role of bacteriophage in population dynamics of a theoretical brine, suggesting low viral production, high host-specificity, and virally-driven DOC cycling may be common within this environment. The results of this dissertation have implications for the understanding of DOC within polar seas and demonstrate the potential for active DOC cycling mediated by bacteria and their viruses within winter sea ice, which serves as an analog for very cold ice elsewhere.
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650 4 $a Microbiology. $3 536250
650 4 $a Marine geology. $3 3173821
650 4 $a Atmospheric sciences. $3 3168354
650 4 $a Biological oceanography. $3 2122748
653 $a Bacteria
653 $a Carbon cycling
653 $a Dissolved organic carbon
653 $a Psychrophile
653 $a Sea-ice brines
653 $a Virus
653 $a Global carbon pool
653 $a Ice formation
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690 $a 0416
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793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28094797