Glycine as a potentially specific biomolecule of semi-labile dissolved organic matter in the ocean

Glycine is the simplest amino acid and a typical of small biomolecule. However it is known to be the most major component of amino acids in dissolved organic matter especially in deep ocean, suggesting a relatively recalcitrant to microbiological degradation and little is known about the actual turnover time of this simple compound in seawater. Thus, we conducted bacterial uptake experiments in the Pacific Ocean with 3H-labeled glycine at in situ concentration label of dissolved free amino acids (sub- nanomolar), and it was found that bacterial uptake rate of glycine was much slower (by up to 6 times) than that of leucine that is a typical of labile amino acid. And the turnover times of glycine were more than 3 days. In addition, another uptake experiment using non-labeled amino acids and high-sensitive detection by UHPLC supported this finding.