Suttle, C.A., A.M. Chan and J.A. Fuhrman. 1991. Dissolved free amino acids in the Sargasso Sea: Uptake and respiration rates, turnover times and concentrations. Marine Ecology Progress Series 70:189-199.

"Clean" techniques and high specific activity tritiated substrates were used to examine bacteria growth rates and uptake kinetics, and estimate turnover times and maximum concentrations (Ks + S) of several dissolved free amino acids (DFAAs) in oligotrophic oceanic waters near Bermuda. Additions of a few nanomolar or less of a particular amino acid was generally but not always sufficient to generate uptake rates consistent with saturation-type kinetics. The proportion of label respired was generally 60 to 80% of the tritium taken up for glutamate, glutamine, alanine, glycine, serine and glucose. For leucine and ornithine < 10% of the tritium taken up was respired. The percentage of label respired was not dependent on the C:N ratio of the substrate or the DFAA concentration, over the range that we examined. Our results indicate that although DFAA pools are small they are rapidly recycled and could be significant sources of C and N for bacterial growth in the Sargasso Sea.