Using High-Sensitivity Lipidomics To Assess Microscale Heterogeneity in Oceanic Sinking Particles and Single Phytoplankton Cells

• Main Authors: Jonathan E. Hunter (11632729), Helen F. Fredricks (2863436), Lars Behrendt (241395), Uria Alcolombri (1756327), Shavonna M. Bent (11632732), Roman Stocker (224989), Benjamin A. S. Van Mooy (10159736)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Biophysics; Biochemistry; Cell Biology; Genetics; Biotechnology; Ecology; Developmental Biology; Marine Biology; Cancer; Inorganic Chemistry; Hematology; Infectious Diseases; Biological Sciences not elsewhere classified; Chemical Sciences not elsewhere classified; providing new insights; planktonic lipid biosynthesis; combine many millions; cell data confirm; physiologically distinct populations; biological carbon pump; assess microscale heterogeneity; oceanic sinking particles; sinking particles; natural heterogeneity; microscale chemical; distinct lipidomes; using high; two types; sinking pom; significant fraction; sensitivity lipidomics; resolution accurate; primary component; possibly indicative; plankton comprise; plankton cells; phytoplankton cells; performance liquid; ocean ’; nanoflow high; microbial processes; ionization high; even cultures; deep sea; chromatography electrospray; carbon export; bulk samples; North Atlantic
• Online Access: https://doi.org/10.1021/acs.est.1c02836.s001

Sinking particulate organic matter (POM) is a primary component of the ocean’s biological carbon pump that is responsible for carbon export from the surface to the deep sea. Lipids derived from plankton comprise a significant fraction of sinking POM. Our understanding of planktonic lipid biosynthesis and the subsequent degradation of lipids in sinking POM is based on the analysis of bulk samples that combine many millions of plankton cells or dozens of sinking particles, which averages out natural heterogeneity. We developed and applied a nanoflow high-performance liquid-chromatography electrospray-ionization high-resolution accurate-mass mass spectrometry lipidomic method to show that two types of sinking particlesmarine snow and fecal pelletscollected in the western North Atlantic Ocean have distinct lipidomes, providing new insights into their sources and degradation that would not be apparent from bulk samples. We pressed the limit of this approach by examining individual diatom cells from a single culture, finding marked lipid heterogeneity, possibly indicative of fundamental mechanisms underlying cell division. These single-cell data confirm that even cultures of phytoplankton cells should be viewed as mixtures of physiologically distinct populations. Overall, this work reveals previously hidden lipidomic heterogeneity in natural POM and phytoplankton cells, which may provide critical new insights into microscale chemical and microbial processes that control the export of sinking POM.