A sensitive fluorescent assay for measuring carbon‐phosphorus lyase activity in aquatic systems

In the oligotrophic ocean where inorganic phosphate (Pi) concentrations are low, microorganisms supplement their nutrient requirements with phosphorus (P) extracted from dissolved organic matter (DOM). Most P in DOM is bound as esters, which hydrolyzed by phosphoesterases to Pi. However, a large fraction of DOM-P occurs phosphonates, reduced organophosphorus compounds CP bond that do not yield Pi through simple ester hydrolysis alone. Phosphonates require an additional step cleaves and oxidizes P(III) P(V) phosphonates metabolized C-P lyase pathway, bonds Pi, enabling microbial assimilation. While activity common such alkaline phosphatase phosphodiesterase can be measured fluorescent assay, comparable method assess (CLA) natural water samples does exist. To address this, we synthesized dansyl-labeled phosphonate compound, its using high performance liquid chromatography. We found laboratory cultures marine bacteria expressing pathway able hydrolyze dansyl phosphonate, while other degradation pathways not. Finally, performed several field tests assay measure column profiles CLA at Sta. ALOHA North Pacific Subtropical Gyre. Activity was elevated near deep chlorophyll maximum suggesting levels region.