A novel method for the measurement of dissolved adenosine and guanosine triphosphate in aquatic habitats: applications to marine microbial ecology

A novel method for the measurement of dissolved adenosine-5'-triphosphate a nd guanosine-5'-triphosphate (D-ATP and D-GTP, respectively) in marine and freshwater habitats was developed and applied to samples collected from the oligotrophic North Pacific Ocean. Both D-ATP and D-GTP are co-precipitated by authigenically formed Mg(OH), and can be concentrated by factors greate r than 200-fold, for subsequent measurement by the firefly luciferin-lucife rase bioluminescence reaction. The detection limit for this method was 2-3 pmol ml(-1) of concentrated sample (equivalent to an in situ concentration of 10 pM) with a 5% precision at concentrations of 10 pmol ml(-1) or above. A significant positive correlation (P < 0.001) was observed between particu late ATP (P-ATP) and D-ATP in water samples collected from Station ALOHA (2 2.75 degreesN, 158 degreesW, depth profiles 0-1000 m). The highest concentr ations of dissolved nucleotides were found in the euphotic zone (0-175 m) b elow which the concentrations were low and relatively invariant. The dissol ved nucleotide pools generally exceeded their corresponding particulate poo ls. Using radioisotopic tracer techniques and the new concentration method, tur nover times for both particulate and dissolved nucleotides can be determine d. The ability to measure concentrations and follow nucleotide tracers accu rately in a very dilute environment provides a unique opportunity to addres s questions on microbial community metabolism, nutrient dynamics and energy flux. (C) 2001 Elsevier Science B.V. All rights reserved.