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08:14
Extraction of Non-Protein Amino Acids from Cyanobacteria for Liquid Chromatography-Tandem Mass Spectrometry Analysis
Published on: December 9, 2022
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Are dissolved free amino acids free?
1Institute of Ecology and Genetics, University of Aarhus, Ny Munkegade, DK-8000, Aarhus C, Denmark.
Microbial Ecology
|November 14, 2013
Summary
Microbial assimilation of amino acids was studied in aquatic environments. Results indicate dissolved free amino acids are utilized by microbes and exist as free molecules, challenging prior research.
Area of Science:
- Environmental microbiology
- Biogeochemistry
- Aquatic ecology
Background:
- Dissolved free amino acids (DFAA) are crucial nutrient sources in aquatic ecosystems.
- Understanding DFAA dynamics is key to microbial ecology and nutrient cycling.
- Previous studies have debated the molecular state and bioavailability of DFAA.
Purpose of the Study:
- To quantify microbial assimilation rates of specific amino acids (glutamic acid, alanine, ornithine) in diverse aquatic environments.
- To compare biological uptake measurements with chemical concentration analyses of DFAA pools.
- To determine if DFAA exist as free, dissolved molecules using molecular size fractionation.
Main Methods:
- Michaelis-Menten kinetics were applied to measure microbial uptake rates.
- Water samples from lakes and marine stations were analyzed.
- Gel permeation chromatography was used to separate dissolved organic matter by molecular size.
Main Results:
- Calculated kinetic parameters (Kt + Sn) consistently exceeded chemically measured concentrations (Sn).
- Uptake rates and concentrations varied significantly across different sites and amino acids.
- A substantial portion of DFAA was recovered in the low molecular weight fraction (<700 Daltons), suggesting they are free molecules.
Conclusions:
- Labeled tracers are effective tools for studying DFAA assimilation.
- DFAA are predominantly free, dissolved molecules in aquatic systems, supporting their direct microbial uptake.
- These findings partially contradict previous reports on DFAA molecular status.
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