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dc.contributor.authorPopendorf, Kimberly J.  Concept link
dc.coverage.spatialSargasso Sea
dc.coverage.spatialNorth Pacific
dc.coverage.spatialNorth Atlantic
dc.coverage.spatialMediterranean Sea
dc.date.accessioned2012-12-21T15:56:32Z
dc.date.available2012-12-21T15:56:32Z
dc.date.issued2013-02
dc.identifier.urihttps://hdl.handle.net/1912/5663
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2013en_US
dc.description.abstractIntact polar diacylglycerolipids (IP-DAGs) were used to study microbial dynamics in the surface ocean. IP-DAGs from surface ocean seawater were quantified using high performance liquid chromatography-mass spectrometry (HPLC-MS), after first developing a sensitive, high throughput molecular ion independent triple quadrupole MS method for quantification. Using this analytical technique I examined the distribution of the nine most abundant classes of IPDAGs across the Mediterranean, and found that phospholipids as a percent of total IP-DAGs correlated with phosphate concentration. Furthermore, phospholipids were a higher percent of total particulate phosphorus where phosphate was higher, ranging from 1-14%. Thus IP-DAGs can play not only a significant but also a dynamic role in defining planktonic nutrient needs and cellular C:N:P ratios in the environment. Additionally, microcosm incubations were amended with phosphate and ammonium, and in the course of several days this elicited a shift in the ratios of IP-DAGs. This study was the first to demonstrate the dynamic response of membrane lipid composition to changes in nutrients in a natural, mixed planktonic community, and indicated that the change in IP-DAG ratios in response to changing nutrients may be a useful indicator of microbial nutrient stress. In the surface waters of the western North Atlantic I used three experimental approaches to identify the microbial sources of the nine most abundant classes of IP-DAGs. Phytoplankton are the primary source of one class of sulfolipid, sulfoquinovosyldiacylglycerol, and one class of betaine lipid, diacylglyceryl-trimethyl-homoserine, while heterotrophic bacteria are the dominant source of the phospholipids phosphatidylglycerol and phosphatidylethanolamine. In regrowth experiments in the Sargasso Sea and the North Pacific I demonstrated that phospholipid specific production rate is representative of heterotrophic bacterial cell specific growth rate. I measured phospholipid specific production rate and bacterial production rate using uptake of 3H-leucine (3H-Leu) and 3H-thymidine (3H-TdR) across the North Atlantic, across the Mediterranean, and in the North Pacific subtropical gyre. I found that phospholipid specific production rates estimate heterotrophic bacterial cell specific growth rates that are on the order of 1 per day, an order of magnitude faster than cell specific growth rates suggested by uptake of 3H-Leu and 3H-TdR.en_US
dc.description.sponsorshipThis research was supported by a National Science Foundation Graduate Research Fellowship, a National Defense Science and Engineering Graduate Fellowship, and grants from the U.S. Office of Naval Research (N00014-09-1-0091 and N00014-06-1-0134) and the U.S. National Science Foundation (OCE-1031143, OCE-1029687, and OCE-0646944).en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.subjectMicrobial ecologyen_US
dc.subjectMicrobiological chemistryen_US
dc.subjectAtlantic Exploer (Ship) Cruise BV39en_US
dc.subjectOceanus (Ship : 1975-) Cruise OC443en_US
dc.subjectL'Atalante (Ship) BOUM Cruiseen_US
dc.subjectKilo Moana (Ship) Cruise KM1013en_US
dc.titleMarine microbial intact polar diacylglycerolipids and their application in the study of nutrient stress and bacterial productionen_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/5663


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