Discerning the mechanisms of coexistence between marine cren/thaumarchaea and marine bacteria via stable isotope probing
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Seyler, Lauren Marie.
Discerning the mechanisms of coexistence between marine cren/thaumarchaea and marine bacteria via stable isotope probing. Retrieved from
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TitleDiscerning the mechanisms of coexistence between marine cren/thaumarchaea and marine bacteria via stable isotope probing
Date Created2015
Other Date2015-10 (degree)
Extent1 online resource (x, 112 p. : ill.)
DescriptionMarine mesophilic archaea were discovered two decades ago. However, the role of these culture-resistant organisms in marine nutrient cycling and the nature of their relationship with bacteria have yet to be elucidated. Current thinking is that thaumarchaea may dominate ammonia oxidation in sediments and oxygen minimum zones, based on the ubiquity of archaeal ammmonium monooxygenase genes. Yet, ammonia-oxidation (or other forms of autotrophy/mixotrophy) may only represent a subset of the full metabolic capability of the phylum. The purpose of this Ph.D. research was to assess whether estuary and marine archaea are autotrophic or heterotrophic and if they compete with bacteria for the same electron donors and acceptors. Salt marsh sediments from a New Jersey state park were screened for heterotrophy using stable isotope probing, by amending with a single 13C-labeled compound (acetate, glycine, or urea), a complex 13C-biopolymer (lipids, proteins, or growth medium), or autotrophy using 13C-bicarbonate. 13C-labeled DNA was analyzed by TRFLP analysis of 16S rRNA genes. SIP analyses indicated salt marsh thaumarchaea and crenarchaea are heterotrophic, double within 2–3 days and often compete with heterotrophic bacteria for the same organic substrates. A clone library of 13C-amplicons was screened to find matches to the 13C-TRFLP peaks. Some of these archaea displayed a preference for particular carbon sources, whereas others incorporated nearly every 13C-substrate provided. Resource partitioning of proteins, and urea at low concentrations, was also observed. SIP was also performed in the open waters of the Sargasso Sea at multiple depths and latitudes, using 13C-labeled acetate, urea, and bicarbonate. In this environment, mixotrophy appeared to be the dominant metabolic strategy, though some heterotrophic OTUs (operational taxonomic units) were observed. No exclusively autotrophic OTUs were detected. Urea was also a competitive substrate in deep waters, with archaea outcompeting bacteria for its uptake in the majority of microcosms. Archaea-specific and bacteria-specific predators were detected via incorporation of 13C into eukaryotic OTUs. This research demonstrates the significance of organic carbon uptake and selective predation on the structuring of marine archaeal communities.
NotePh.D.
NoteIncludes bibliographical references
Noteby Lauren Marie Seyler
Genretheses, ETD doctoral
Languageeng
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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