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Phosphorus limitation of ‘ Candidatus Pelagibacter ubique’ (SAR11). Presented by: Emily Campbell PI: Dr. Stephen Giovannoni Mentor: Paul Carini Marine Microbiology Lab. http://giovannonilab.oregonstate.edu. SAR11. CO 2. Heterotrophs. Autotrophs. Organic Carbon.
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Phosphorus limitation of ‘Candidatus Pelagibacter ubique’ (SAR11) Presented by: Emily Campbell PI: Dr. Stephen Giovannoni Mentor: Paul Carini Marine Microbiology Lab http://giovannonilab.oregonstate.edu
SAR11 CO2 Heterotrophs Autotrophs Organic Carbon • Discovered in 1990 by Stephen Giovannoni • Most abundant heterotrophic organism in ocean surface waters world wide • 1/3 of cells present in ocean surface water • Role of SAR11 • Dissolved organic carbon cycling • SAR11 oxidizes carbon → Releases CO2 • Ocean lacks large quantities of key nutrients
Phosphorus • Most commonly found as phosphate (PO4) • An example of a nutrient found at low concentrations • Below 5 nM • Required for all living things • Nucleotides (DNA and RNA), phospholipids (cell membranes) • SAR11 thrives in low phosphate environments
3 Isolates with Sequenced Genomes • SAR11 isolate HTCC7211, HTCC1062, HTCC1002
Hypothesis & Prediction • Hypothesis: • Each SAR11 isolate can utilize different phosphorus compounds with varying abilities. • Prediction: • If the isolate is able to utilize the given phosphorus-containing compound, we expect to observe maximum cell densities in excess of those cultures to which no phosphate has been added.
Experimental Overview Test Compound Negative Control Positive Control Count Cells Plot Data
Phosphorus Compounds • 2-aminoethylphosphate • cAMP • D-xylulose-phosphate • dATP • dCTP • dGTP • dTTP • D-Glucose 6 Phosphate • 3-glycerophosphate • AMP • CMP • GMP • IMP • UMP • L-O Phosphoserine • Methylphosphate • Phosphite dibasic pentahydrate • PhosphoenolPyruvate • Phosphonoacetic acid • PhyticAcid • D-ribose-5 phosphate • Sodium phosphite dibasic pentahydrate • Sodium Phosphonoformate • Sodium triphosphate • Uridine-5`-diphosphoglucose • DNA • RNA
HTCC7211 HTCC1002 • IMP • Uridine5’ diphosphoglucose • Methylphosphonate • L-O Phosphoserine • 2-aminoethylphosphonate • dGTP • dTTP • D-xylulose-phosphate • D-ribose-5 phosphate • dATP • dCTP • D-glucose-6P • 3-glycerophosphate • PEP • Phosphite • Phosphonoformate • UMP • GMP HTCC1062
Future directions • Verify results • Free phosphorus in stocks • Test positive results in triplicate • What molecular pathways the compound could be used in • What other necessities the phosphorus compound being transported could alleviate
Acknowledgements Dr. Stephen Giovannoni Paul Carini HHMI Dr. Kevin Ahern