Dissolved organic phosphorus utilization by phytoplankton reveals preferential degradation of polyphosphates over phosphomonoesters

Julia M. Diaz, Alisia Holland, James G. Sanders, Karrie Bulski, Douglas Mollett, Chau Wen Chou, Dennis Phillips, Yuanzhi Tang, Solange Duhamel

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


The nutritionally available pool of dissolved organic phosphorus (DOP) supports marine primary productivity in a range of ocean ecosystems but remains poorly resolved. Here, the relative lability of model phosphorus (P) compounds representing the major P(V) bond classes of marine DOP - phosphomonoesters (P-O-C) and phosphoanhydrides (P-O-P) - was assessed in diatom cultures of the genus Thalassiosira, as well as coastal field sites of the western North Atlantic. In diatom samples, maximum enzymatic hydrolysis rates revealed that the P-anhydride bonds of inorganic tripolyphosphate (3poly-P), followed by the P-anhydride bonds of adenosine 5'-triphosphate (ATP), were preferentially degraded relative to the P-monoesters adenosine 5'-monophosphate (AMP) and 4-methylumbelliferone phosphate (MUF-P). Consistent with these rate measurements, targeted proteomics analysis demonstrated that the underlying phosphatase diversity present in diatom samples was dominated by P-anhydride degrading enzymes (inorganic pyrophosphatases and nucleoside triphosphatases). Furthermore, biomass-normalized rates of ATP degradation were always suppressed under P-replete conditions in diatom cultures, but the effect of overall P availability on 3poly-P degradation was inconsistent among diatom strains, suggesting that inorganic polyphosphate (poly-P) degradation may persist irrespective of prevailing P levels in the marine environment. Indeed, the majority of field sites examined in the P-replete coastal western North Atlantic exhibited significantly higher maximum rates of inorganic poly-P hydrolysis relative to P-monoester hydrolysis, which was largely driven by phytoplankton dynamics. Based on these results, the possibility that P-anhydride utilization may contribute comparably or even more substantially than P-esters to community-level P demand, phytoplankton growth, and primary productivity should be considered.

Original languageEnglish (US)
Article number380
JournalFrontiers in Marine Science
Issue numberOCT
StatePublished - Oct 25 2018
Externally publishedYes


  • Alkaline phosphatase activity
  • Diatom
  • Dissolved organic phosphorus
  • Phosphoanhydride
  • Phosphoester
  • Phosphorus stress
  • Polyphosphate
  • Thalassiosira

ASJC Scopus subject areas

  • Oceanography
  • Global and Planetary Change
  • Aquatic Science
  • Water Science and Technology
  • Environmental Science (miscellaneous)
  • Ocean Engineering


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