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Scott Gifford, Oscar Sosa, Dan Repeta , Ed DeLong

Methylotrophs Dominate Dilution-to-Extinction Cultures Enriched with Marine Dissolved Organic Matter. Scott Gifford, Oscar Sosa, Dan Repeta , Ed DeLong. 750 GT C. CO 2. CO 2. Particulate carbon. 10-20 GT C. Release Mechanisms. Lysis Grazing Leakage. Dissolved Organic Carbon (DOC).

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Scott Gifford, Oscar Sosa, Dan Repeta , Ed DeLong

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  1. Methylotrophs Dominate Dilution-to-Extinction Cultures Enriched with Marine Dissolved Organic Matter Scott Gifford, Oscar Sosa, Dan Repeta, Ed DeLong

  2. 750 GT C CO2 CO2 Particulate carbon 10-20 GT C Release Mechanisms Lysis Grazing Leakage Dissolved Organic Carbon (DOC) 660 GT C

  3. lability labile semi-labile refractory hr -days ? 1,000 – 2000 years HMW Dissolved Organic Carbon (DOC) 660 GT C

  4. What is the chemical composition of DOC? Which microorganisms consume DOC? What are the genes involved in DOC degradation? Chemical Characterization Biology • DOC Ed DeLong Dan Repeta Rene Boiteau Oscar Sosa Dissolved Organic Carbon (DOC)

  5. HMW DOM collection Tangential flow filtration with 1kDa filter www.nelha.org Karl et al 1998

  6. Chemical Characterization Ultrafiltration to obtain DOM Isolates Courtesy Dan Repeta

  7. Dilution to extinction culturing transfer transfer 106 cells ml-1 5-10 cells ml-1 inoculated well control well A 1 2 3 4 5 6 7 8 incubate B C FALCON D [DOM] E F

  8. Dil-to-Ext with a DOM twist Inoculant North Atlantic: Nahant Bay • DOM North Pacific : NEHLA Nahant Bay Boston

  9. Flow cytometry Screen wells for growth with flowcytometry side scatter log green fluorescence <105 105 5 X 105 106 or >

  10. Isolates have a distinct growth response to DOM 100x DOM cells per ml 20x DOM 5x DOM no DOM days

  11. 88% of isolates are methylotrophs Isolate Phylogeny (small subunit rDNA) 93 Isolates 88 obtain 16S rDNA 10 Gammaproteobacteria 5 Alteromonads 3 SAR92 2 Vibrios 78 Betaproteobacteria 78 unclassified Methylophilales_ otu_2801_

  12. Isolate growth on methanol…. Isolates can degrade C1 compounds 3 2 cells per ml X 106 1 cells per ml days No MeOH 150 µM methanol No MeOH 150 µM methanol days

  13. DOM transcripts microcosm Same FunctionalGroup Same Taxa

  14. Methylotrophs CH CH HMW DOC 3 3 Alteromonads

  15. Current work….. Substrate experiments Purified DOM C1 compounds Complex Carbs. porphyrin, xylan pectin, etc., Genomics Transcriptomics Draft genomes for 73 isolates

  16. Conclusions Dilution cultures enriched with DOM produced more isolates Isolates have a distinct growth response to DOM Isolate collection is dominated by methylotrophs Hypothesize methylotrophs may have ability to use C1 compounds from DOM polymer Acknowledgements Jamie Becker Rene Boiteau Chon Martinez TsultrimPalden John Eppley Sara Lincoln

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