Amino acids in interstitial waters from ODP Sites 689 and 690 on the Maud Rise, Antarctic Ocean.

Abstract

Biogenic calcareous and siliceous sediments were drilled at ODP Sites 689 and 690 on the Maud Rise, Antarctic Ocean. We analyzed dissolved combined amino acids (DCAA) and dissolved free amino acids (DFAA) in interstitial waters in order to characterize the amino acids in dissolved organic matter. The DFAA was predominant over the DCAA in interstitial waters at Sites 689 and 690, which contradicted the previous results from interstitial water and seawater studies. The DCAA in the interstitial waters probably originated from calcareous biogenic debris with less amounts of siliceous debris. Although glutamic acid constituted 41% of the total concentration of DCAA, it accounted for only 1% of the total concentration of DFAA due to the adsorption and/or reaction with biogenic carbonate. Ornithine, a nonprotein amino acid, is a decomposed product of arginine and made up 17 mol% of the total DFAA and. The total hydrolyzable amino acids (=DCAA + DFAA) accounted for 5 to 28% of the dissolved organic carbon (DOC) concentration, which implied that high molecular weight organic matter was a major contributor for the DOM (dissolved organic matter) in interstitial waters. Fairly positive correlation between the dissolved manganese and the total DCAA values suggested that the redox condition plays a significant role in controlling the total DCAA content. A small decrease in the sulfate concentration in the interstitial waters from both sites suggested fairly low microbial activity by sulfate-reducing bacteria.

Biogeographic partitioning of Southern Ocean microorganisms revealed by metagenomics

“…The histidine biosynthesis module was also overrepresented in the SZ. While the concentration of dissolved histidine in the SO is generally low (Kawahata and Ishizuka, ), blooming eukaryotic phytoplankton (which are more prevalent in the SZ) may deplete nitrate while releasing dissolved free amino acids (DFAA). As DFAA become available, they are used by bacteria to sense the decaying bloom.…”

Sediment Pore Waters

“…In contrast to studies of DFAAs, there have been far fewer studies of DCAAs in marine sediment pore waters (Caughey, 1982;Kawahata and Ishizuka, 2000;Lomstein et al, 1998;Ogasawara et al, 2001;Pantoja and Lee, 1999). In general, concentrations of total DCAAs are ~1.5-4 times that of total DFAAs.…”

Sensitive Determination of Dissolved Tryptophan in Freshwater by Alkaline Hydrolysis and HPLC

“…[1][2][3][4] However, the analysis of tryptophan still remains unsolved due to its lability to acid and trace oxygen which are usually used for acid hydrolysis of water samples. Recently, the fluorescence similar to tryptophan standard fluorescence has been extensively studied in aquatic environments, and is usually categorized as tryptophan-like or protein-like fluorescence.…”