Biogenic phosphonate utilization by globally distributed diatomThalassiosira

Abstract

Phosphonate is a class of enigmatic organic phosphorus compounds that contribute ~25% of total dissolved organic phosphorus (DOP). Recent studies reveal the important role of phosphonate mediated by prokaryotes in the marine P redox cycle, however, its bioavailability and metabolic process by eukaryotic phytoplankton are under debate. 2-Aminoethylphosphonic acid and (2-AEP) and 2-amino-3-phosphonopropionic acid (2-AP3) are two biogenic phosphonates that ubiquitously exist in marine environment. Here, we report that Thalassiosira pseudonana, a dominant diatom species in the ocean, are able to recover growth from phosphorus starvation with individual supplement of 2-AEP and 2-AP3. Moreover, the cellular stoichiometric C:P and N:P ratios of cells grown under 2-AEP are in-between the P-depleted and DIP-replete groups. This study provided evidence that biogenic phosphonates can be adopted as alternative phosphorus sources to support diatom growth and might have a profound effect on the elemental stoichiometry in the oligotrophic ocean.