Ectoenzymatic activity and uptake of monomers in marine bacterioplankton described by a biphasic kinetic model
- Author(s)
- M. Unanue, B. Ayo, M. Agis, D. Slezak, G. J. Herndl, J. Iriberri
- Abstract
The kinetics of bacterial hydrolytic ectoenzymatic activity and the uptake of monomeric compounds were investigated in the Northwestern Mediterranean Sea. Aminopeptidase and α- and β-glucosidase activities were analyzed by using fluorogenic substrates at 15-22 concentrations ranging from I nM to 500 μM. Radiolabeled glucose and a mixture of amino acids were chosen as representatives of monomeric compounds, and the bacterial uptake rates (assimilation plus respiration) were determined over a wide range of substrate concentrations (from 0.2 nM to 3 μM). We found biphasic kinetics both for hydrolytic enzymes and uptake systems: high affinity enzymes at low concentrations of substrates (K(m) values ranged from 48 nM to 2.7 μM for ectoenzymes and from 1.4 nM to 42 nM for uptake systems), and low affinity enzymes at high concentrations of substrates (K(m) values ranged from 13 μM to 142 μM for ectoenzymes and from 0.1 μM to 1.3 μM for uptake systems). Transition between high and low affinity enzymes was observed at 10 μM for aminopeptidase and from 1 μM to 25 μM for glucosidases, and it was more variable and less pronounced for the uptake of glucose (40 nM-0.28 μM) and amino acids (10 nM-0.16 μM). Results showed that the potential rates of hydrolysis and uptake are tightly coupled only if the high affinity hydrolytic ectoenzymes and the low affinity uptake systems are operating simultaneously.
- Organisation(s)
- External organisation(s)
- University of the Basque Country, Universität Wien
- Journal
- Microbial Ecology
- Volume
- 37
- Pages
- 36-48
- No. of pages
- 13
- ISSN
- 0095-3628
- DOI
- https://doi.org/10.1007/s002489900128
- Publication date
- 01-1999
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 106021 Marine biology
- ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics, Ecology, Soil Science
- Sustainable Development Goals
- SDG 14 - Life Below Water
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/ectoenzymatic-activity-and-uptake-of-monomers-in-marine-bacterioplankton-described-by-a-biphasic-kinetic-model(b9eb7598-ca58-4b49-82cc-30120787ee75).html