Author: Gordon Maxwell Showalter
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
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.
Author: Robert Edward Hodson
Publisher:
ISBN:
Category : Bacteria
Languages : en
Pages : 350
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Book Description
Author: David N. Thomas
Publisher: John Wiley & Sons
ISBN: 1118778383
Category : Science
Languages : en
Pages : 666
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Book Description
Over the past 20 years the study of the frozen Arctic and Southern Oceans and sub-arctic seas has progressed at a remarkable pace. This third edition of Sea Ice gives insight into the very latest understanding of the how sea ice is formed, how we measure (and model) its extent, the biology that lives within and associated with sea ice and the effect of climate change on its distribution. How sea ice influences the oceanography of underlying waters and the influences that sea ice has on humans living in Arctic regions are also discussed. Featuring twelve new chapters, this edition follows two previous editions (2001 and 2010), and the need for this latest update exhibits just how rapidly the science of sea ice is developing. The 27 chapters are written by a team of more than 50 of the worlds’ leading experts in their fields. These combine to make the book the most comprehensive introduction to the physics, chemistry, biology and geology of sea ice that there is. This third edition of Sea Ice will be a key resource for all policy makers, researchers and students who work with the frozen oceans and seas.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The flux of dissolved organic matter (DOM) through aquatic bacterial communities is a major process in carbon cycling in the oceans and other aquatic systems. Our work addressed the general hypothesis that the phylogenetic make-up of bacterial communities and the abundances of key types of bacteria are important factors influencing the processing of DOM in aquatic ecosystems. Since most bacteria are not easily cultivated, the phylogenetic diversity of these microbes has to be assessed using culture-independent approaches. Even if the relevant bacteria were cultivated, their activity in the lab would likely differ from that under environmental conditions. This project found variation in DOM uptake by the major bacterial groups found in coastal waters. In brief, the data suggest substantial differences among groups in the use of high and molecular weight DOM components. It also made key discoveries about the role of light in affecting this uptake especially by cyanobacteria. In the North Atlantic Ocean, for example, over half of the light-stimulated uptake was by the coccoid cyanobacterium, Prochlorococcus, with the remaining uptake due to Synechococcus and other photoheterotrophic bacteria. The project also examined in detail the degradation of one organic matter component, chitin, which is often said to be the second most abundant compound in the biosphere. The findings of this project contribute to our understanding of DOM fluxes and microbial dynamics supported by those fluxes. It is possible that these findings will lead to improvements in models of the carbon cycle that have compartments for dissolved organic carbon (DOC), the largest pool of organic carbon in the oceans.
Author: Edward F. DeLong
Publisher: Springer
ISBN: 9783642301193
Category : Science
Languages : en
Pages : 567
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Book Description
The Prokaryotes is a comprehensive, multi-authored, peer reviewed reference work on Bacteria and Achaea. This fourth edition of The Prokaryotes is organized to cover all taxonomic diversity, using the family level to delineate chapters. Different from other resources, this new Springer product includes not only taxonomy, but also prokaryotic biology and technology of taxa in a broad context. Technological aspects highlight the usefulness of prokaryotes in processes and products, including biocontrol agents and as genetics tools. The content of the expanded fourth edition is divided into two parts: Part 1 contains review chapters dealing with the most important general concepts in molecular, applied and general prokaryote biology; Part 2 describes the known properties of specific taxonomic groups. Two completely new sections have been added to Part 1: bacterial communities and human bacteriology. The bacterial communities section reflects the growing realization that studies on pure cultures of bacteria have led to an incomplete picture of the microbial world for two fundamental reasons: the vast majority of bacteria in soil, water and associated with biological tissues are currently not culturable, and that an understanding of microbial ecology requires knowledge on how different bacterial species interact with each other in their natural environment. The new section on human microbiology deals with bacteria associated with healthy humans and bacterial pathogenesis. Each of the major human diseases caused by bacteria is reviewed, from identifying the pathogens by classical clinical and non-culturing techniques to the biochemical mechanisms of the disease process. The 4th edition of The Prokaryotes is the most complete resource on the biology of prokaryotes. The following volumes are published consecutively within the 4th Edition: Prokaryotic Biology and Symbiotic Associations Prokaryotic Communities and Ecophysiology Prokaryotic Physiology and Biochemistry Applied Bacteriology and Biotechnology Human Microbiology Actinobacteria Firmicutes Alphaproteobacteria and Betaproteobacteria Gammaproteobacteria Deltaproteobacteria and Epsilonproteobacteria Other Major Lineages of Bacteria and the Archaea
Author: Simon Jungblut
Publisher: Springer Nature
ISBN: 3030203891
Category : Aquatic biology
Languages : en
Pages : 378
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Book Description
This open access book summarizes peer-reviewed articles and the abstracts of oral and poster presentations given during the YOUMARES 9 conference which took place in Oldenburg, Germany, in September 2018. The aims of this book are to summarize state-of-the-art knowledge in marine sciences and to inspire scientists of all career stages in the development of further research. These conferences are organized by and for young marine researchers. Qualified early-career researchers, who moderated topical sessions during the conference, contributed literature reviews on specific topics within their research field. .
Author: Byron Pedler Sherwood
Publisher:
ISBN: 9781321235449
Category :
Languages : en
Pages : 165
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Book Description
The ocean contains one of the largest reservoirs of reduced carbon on Earth in the form of dissolved organic matter (DOM). Heterotrophic bacteria serve as the primary force regulating the degradation of this material, recycling the majority of dissolved organic carbon (DOC) produced in the surface ocean by phytoplankton back to carbon dioxide. While it is known that microbial community structure plays a role in determining the rate and magnitude of DOM turnover, the quantitative contribution of individuals to this process remains unknown. The objective of this dissertation was to investigate the constraints on DOM turnover by bacterial communities by focusing on how a single bacterial strain makes a living in the sea. I found that a single bacterial strain, Alteromonas sp. AltSIO, has the capacity to consume an equivalent magnitude of DOC as diverse bacterial communities, suggesting that bacterial diversity may not be required for the complete removal of labile DOC in the surface ocean. In long-term microcosms, however, bacterial diversity was required for continued degradation of semi-labile DOC. To test the generality of this capacity among individual bacteria, a culture-based study was conducted where >100 phylogenetically diverse bacterial strains were isolated to screen for growth in unamended seawater. No other bacterial strain tested exhibited the capacity to consume a measureable quantity of DOC when grown in isolation, suggesting that this phenomenon may not be common among readily culturable marine bacteria. Physiological investigations of this isolate reveal a broad capacity for processing carbohydrates, yet an apparent preference for disaccharides and inability to metabolize glucose. Genomic analysis confirmed that this strain lacks a glucose-specific permease required for the exogenous uptake of glucose, but is endowed with additional carbohydrate-specific transporters not found in genomes of closely related bacterial strains. Genomic insights also show the potential to reduce nitrate, a high capacity to scavenge iron, and a complete chemotaxis apparatus potentially used for disaccharide acquisition. DOM characterization by ultrahigh resolution mass spectrometry revealed that AltSIO and diverse seawater communities significantly alter the composition of ambient DOM.
Author: Ryan Guillemette
Publisher:
ISBN:
Category :
Languages : en
Pages : 114
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Book Description
This dissertation investigates the mechanisms of bacterial utilization of cells and cellular debris in the ocean. Bacteria are key members of marine ecosystems. They serve as the predominant biotic force acting on marine biogeochemical cycling of organic matter, and exert a strong influence on marine microbial community dynamics via their cell-cell interactions. While scientists have begun to untangle the web of seemingly intractable mechanisms that marine bacteria use to acquire and consume organic matter, many unknowns still remain. This research implements a number of techniques including bacterial production measurements, mass spectrometry, single-cell analyses, and genetics to test two hypotheses: (1) that bacteria can readily respond to a natural pulse of cellular debris from coral mass-spawning, and (2) that contact-dependent predatory bacteria can kill and consume their bacterial prey. Studies conducted off coastal Panama found that coral gametes elevated the organic matter concentration of the surrounding seawater by ~5-fold after a mass spawning event. Bacterial production measurements and 454 pyrosequencing of bromodeoxyuridine-labeled 16S bacterial rRNA genes showed that it was primarily active Rhodobacteraceae, Flavobacteriaceae, and Saprospiraceae taxa that degraded the coral gametes. High resolution mass spectrometry analysis supported this hypothesis, showing trends that indicated microbial alteration of the organic matter pool. This study demonstrated that coastal marine bacteria can readily respond to a large input of autochthonous cellular debris. Contact-dependent bacterial predation was tested by using bacteria with a type 6 secretion system (T6SS+) as model predators in competition assays. Nanoscale secondary ion mass spectrometry analysis showed that T6SS+ Vibrio cholerae utilized carbon from its bacterial prey. V. cholerae also exhibited the ability to utilize DNA and ribosomes from lysed bacteria as nutrients. Additionally, independent competition assays between T6SS+ V. cholerae and 15 different marine bacterial isolates showed that V. cholerae and/or the challenged isolate were killed in 12 out of the 15 assays. The experiments also revealed that the coral and shellfish pathogen, Vibrio coralliilyticus has a functional T6SS. Collectively, these results demonstrate that bacterial antagonism often ends in carnage for one or both of the competing species, and suggest that the susceptible prey are fresh fodder for the victorious bacterium.
Author: David N. Thomas
Publisher: John Wiley & Sons
ISBN: 9781444317152
Category : Technology & Engineering
Languages : en
Pages : 641
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Book Description
As the Arctic perennial sea ice continues to disappear at an alarming rate, a full understanding of sea ice as a crucial global ecosystem, and the effects of its loss is vital for all those working with and studying global climate change. Building on the success of the previous edition, the second edition of Sea Ice, now much expanded and in full colour throughout, includes six completely new chapters with complete revisions of all the chapters included from the first edition. The Editors, Professor David Thomas and Dr Gerhard Dieckmann have once again drawn together an extremely impressive group of internationally respected contributing authors, ensuring a comprehensive worldwide coverage of this incredibly important topic. Sea Ice, second edition, is an essential purchase for oceanographers and marine scientists, environmental scientists, biologists, geochemists and geologists. All those involved in the study of global climate change will find this book to contain a wealth of important information. All libraries in universities and research establishments where these subjects are studied and taught will need multiple copies of this book on their shelves. truly multidisciplinary approach world leading authors and editors international in scope, covering both Arctic and Antarctic work of vital interest to all those involved in global warming and climate change research highly illustrated full colour book with colour images throughout
Author: Selman Abraham Waksman
Publisher:
ISBN:
Category :
Languages : en
Pages :
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