Dissolved Organic Phosphorus Utilization by Phytoplankton Reveals Preferential Degradation of Polyphosphates Over Phosphomonoesters

Preferential utilization of inorganic polyphosphate over other bioavailable phosphorus sources by the model diatoms Thalassiosira spp.

“…In a prior study, degradation rates of 3polyP, ATP, AMP and 4‐methylumbelliferyl phosphate (MUF‐P) were determined in cell‐free (0.2 μm filtered) exudates of Thalassiosira spp (Diaz et al ., ). In contrast, the aim of the present study was to determine degradation rates of the same P sources by living, intact cells.…”

“…). These trends confirm and corroborate the preferential degradation of extracellular 3polyP relative to ATP and AMP by Thalassiosira spp., as previously suggested based on DOP dynamics in the cell‐free exudates of these cultures (Diaz et al ., ). Despite the preferential extracellular degradation of 3polyP (Fig.…”

“…during a similar point in stationary phase. As expected, DOP degradation rates in cell‐free filtrates were relatively low, typically no more than 30% of the rates observed here in whole cultures (Diaz et al ., ). This result is consistent with filtration removing most of the DOP hydrolytic activity.…”

“…In a previous study by Diaz et al . (), the degradation rates of 3polyP, ATP, AMP and MUF‐P were determined in filtered cell‐free samples of Thalassiosira spp. during a similar point in stationary phase.…”

“…Thalassiosira pseudonana and Thalassiosira weissflogii were reportedly unable to utilize inorganic polyphosphate as a sole P source, according to one prior study (Diaz et al ., ). Yet paradoxically, we recently found that inorganic polyphosphate is rapidly hydrolysed by cell‐free (0.2 μm filtered) exudates of T. pseudonana (Diaz et al ., ), leading us to question the original negative bioavailability result. In order to address this inconsistency and clarify the potential role of inorganic polyphosphate as a P source for phytoplankton growth, we assessed the ability of four strains of Thalassiosira spp.…”