Dissolved organic matter produced by Thalassiosira pseudonana

Abstract

13Phytoplankton are significant producers of dissolved organic matter (DOM) in marine 14 ecosystems but the identity and dynamics of this DOM remain poorly constrained. Knowledge 15 on the identity and dynamics of DOM are crucial for understanding the molecular-level reactions 16 at the base of the global carbon cycle. Here we apply emerging analytical and computational 17 tools from metabolomics to investigate the composition of DOM produced by the centric diatom 18 Thalassiosira pseudonana. We assessed both intracellular metabolites within T. pseudonana (the 19 endo-metabolome) and extracellular metabolites released by T. pseudonana (the exo-20 metabolome). The intracellular metabolites had a more variable composition than the 21 extracellular metabolites. We putatively identified novel compounds not previously associated 22 with T. pseudonana as well as compounds that have previously been identified within T. 23 pseudonana's metabolic capacity (e.g. dimethylsulfoniopropionate and degradation products of 24 chitin). The resulting information will provide the basis for future experiments to assess the 25 impact of T. pseudonana on the composition of dissolved organic matter in marine 26 environments. 27 3

Release of ecologically relevant metabolites by the cyanobacterium Synechococcus elongatus CCMP 1631

“…In order to determine the impact of the metabolism of the cosmopolitan cyanobacterium, Synechococcus elongatus, on DOM composition, as well as to quantify diverse and unexpected metabolites associated with S. elongatus, we applied both targeted and untargeted metabolomics techniques to analyze intra-and extracellular metabolites derived from cultures of S. elongatus. Few metabolomics studies have examined both intra-and extracellular metabolite profiles of marine microbes (Baran et al, 2010;Rosselló-Mora et al, 2008;Longnecker et al, 2015). The intracellular dataset described here thus provided unique insight into the metabolism of S. elongatus and highlighted specific compounds with undefined functional roles as targets for future physiological and biochemical studies.…”

Ubiquitous marine bacterium inhibits diatom cell division

“…We examined in more detail, the interaction between strain SA60, and the model diatom T. pseudonana CCMP 1335 because the annotated whole genome of this diatom is available (Armbrust et al, 2004), with complementary metabolomic data (Longnecker et al, 2015), and because the cells are small enough to analyze with flow cytometry.…”

“…In addition, the C. atlanticus genome encodes a variety of peptidases and carbohydrate active enzymes (CAZYmes) and C. atlanticus can grow in defined media with amino acids as its sole source of organic carbon and nitrogen (data not shown). Secretion of carbohydrates and peptides by T. pseudonana (Longnecker et al, 2015) could also fulfill C. atlanticus nutritional requirements.…”

Environmental metabolomics: Analytical strategies

“…Intracellular metabolites were then extracted from the resulting cell pellet and analyzed by our untargeted metabolomics method (Longnecker et al, 2015). To increase the biomass in each extraction, we now use filtration to collect cells and, as expected, this has increased the number of detected intracellular features.…”

“…Studies to date include measurements of specific metabolite classes in seawater, such as B vitamins (Heal et al, 2014;Sañudo-Wilhelmy et al, 2012), as well as broader assessments of primary and secondary metabolites within marine microbial cultures (Baran et al, 2010;Bennette et al, 2011;Fiore et al, in press;Longnecker et al, 2015;Paul et al, 2009;Romano et al, 2014).…”