Marine microbial intact polar diacylglycerolipids and their application in the study of nutrient stress and bacterial production

• Main Author: Popendorf, Kimberly J. (Kimberly Julia)
• Other Authors: Benjamin A.S. Van Mooy., Woods Hole Oceanographic Institution., Joint Program in Oceanography/Applied Ocean Science and Engineering, Woods Hole Oceanographic Institution, Massachusetts Institute of Technology. Department of Biology
• Format: Thesis
• Language: English
• Published: Massachusetts Institute of Technology 2013
• Subjects: Joint Program in Oceanography/Applied Ocean Science and Engineering; Earth; Atmospheric; and Planetary Sciences; Woods Hole Oceanographic Institution; Phospholipids; Marine microbial ecology; Marine bacteria; Marine plankton; Nutrient cycles; Microbial metabolism; North Atlantic
• Online Access: http://hdl.handle.net/1721.1/79293

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Biology; and the Woods Hole Oceanographic Institution), February 2013. "February 2013." Cataloged from PDF version of thesis. Includes bibliographical references. Intact 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 ...