Chemical characterization of metabolites across gradients of productivity in the California Current Ecosystem

Around half of ocean primary production is processed through the labile dissolved organic matter pool. The molecular composition of these metabolites may reveal the role of organic matter in driving microbial ecology and metabolic processes controlling global carbon and nutrient cycling. Mass spectrometry-based approaches characterizing marine organic matter are usually limited to elemental characteristics via molecular formula assignment. To understand metabolic processes associated with organic matter, however, a deeper exploration into the functional properties of metabolites is required. The California Current Ecosystem (CCE) region exhibits strong gradients in microbial community structure, nutrients, and primary production, providing an ideal location to observe the ecological interactions and structural changes in the organic matter pool. Here, we compare molecular signatures from three Lagrangian-based cruises in the CCE. Solid phase extraction via liquid chromatography mass spectrometry conjoined with in-silico tools (SIRIUS) and the chemical classification tool NPClassifier reveal biosynthetic origins and structural properties responsible for observed changes in metabolites. Hierarchical clustering followed by biogeochemical correlations (changes in nutrient, particulate organic matter, productivity, etc.) reveal specific molecules and molecular classes that fluctuate within this upwelling system. Further comparison of species composition via 16S and 18S sequencing reveals organisms that are disproportionately responsible for trends in our molecular analysis.

Presentation Preference: Oral

Primary Presenter: Ralph Riley Torres, Scripps Institution of Oceanography (rrtorres@ucsd.edu)

Authors:

Ralph Riley Torres, Scripps Institution of Oceanography  (rrtorres@ucsd.edu)

Irina Koester, Scripps Institution of Oceanography  (ikoester@ucsd.edu)

Daniel Petras, University of California Riverside  (dpetras@ucr.edu)

Sarah Schwenck, Scripps Institution of Oceanography  (sschwenc@ucsd.edu)

Sara Rivera, University of Michigan  (sarariv@umich.edu)

Abzer Shah, University of Tuebingen  (abzer.kelmina@gmail.com)

Andrew Allen, Scripps Institution of Oceanography / J.Craig Venter Institute  (aallen@ucsd.edu)

Pieter Dorrestein, University of California, San Diego  (pdorrestein@health.ucsd.edu)

Lihini Aluwihare, Scripps Institution of Oceanography  (laluwihare@ucsd.edu)