FN Archimer Export Format
PT J
TI Spatial patterns of ectoenzymatic kinetics in relation to biogeochemical properties in the Mediterranean Sea and the concentration of the fluorogenic substrate used
BT 
AF Van Wambeke, France
   Pulido, Elvira
   Catala, Philippe
   Dinasquet, Julie
   Djaoudi, Kahina
   Engel, Anja
   Garel, Marc
   Guasco, Sophie
   Barbara, Marie
   Nunige, Sandra
   Taillandier, Vincent
   Zancker, Birthe
   Tamburini, Christian
AS 1:1;2:1;3:3;4:2,3;5:1,4;6:5;7:1;8:1;9:3;10:1;11:6;12:6,7;13:1;
FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:;
C1 Aix-Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288, Marseille, France
   Marine Biology Research Division, Scripps Institution of Oceanography, UCSD, La Jolla, USA
   Sorbonne Universités, UPMC University Paris 6, Laboratoire d'Océanographie Microbienne (LOMIC), Observatoire Océanologique, 66650, Banyuls/mer, France
   Molecular and Cellular Biology, The University of Arizona, Tucson, USA
   GEOMAR – Helmholtz-Centre for Ocean Research, Kiel, Germany
   CNRS, Sorbonne Universités, Laboratoire d’Océanographie de Villefranche (LOV), UMR7093, 06230 Villefranche sur-Mer, France
   The Marine Biological Association of the UK, Plymouth, United Kingdom
C2 UNIV AIX MARSEILLE, FRANCE
   UNIV CALIF SAN DIEGO, USA
   UNIV PARIS 6, FRANCE
   UNIV ARIZONA, USA
   IFM GEOMAR, GERMANY
   CNRS, FRANCE
   MBA, UK
IN DOAJ
IF 5.092
TC 7
UR https://archimer.ifremer.fr/doc/00642/75452/76268.pdf
   https://archimer.ifremer.fr/doc/00642/75452/76269.pdf
   https://archimer.ifremer.fr/doc/00642/75452/83086.pdf
   https://archimer.ifremer.fr/doc/00642/75452/83088.pdf
LA English
DT Article
CR PEACETIME
BO Pourquoi pas ?
AB Ectoenzymatic activity, prokaryotic heterotrophic abundances and production were determined in the Mediterranean Sea. Sampling was carried out in the sub-surface, the deep chlorophyll maximum layer (DCM), the core of the Levantine intermediate waters and in the deeper part of the mesopelagic layers. Michaelis–Menten kinetics were assessed using a large range of concentrations of fluorogenic substrates (0.025 to 50 µM). As a consequence, Km (Michaelis–Menten half-saturation constant) and Vm (maximum hydrolysis velocity) parameters were determined for both low- and high-affinity enzymes for alkaline phosphatase, aminopeptidase (LAP) and β-glucosidase (βGLU). Based on the constant derived from the high-LAP-affinity enzyme (0.025–1 µM substrate concentration range), in situ hydrolysis of N proteins contributed 48 % ± 30 % to the heterotrophic bacterial nitrogen demand within the epipelagic layers and 180 % ± 154 % in the Levantine intermediate waters and the upper part of the mesopelagic layers. The LAP hydrolysis rate was higher than bacterial N demand only within the deeper layer and only when considering the high-affinity enzyme. Based on a 10 % bacterial growth efficiency, the cumulative hydrolysis rates of C proteins and C polysaccharides contributed on average 2.5 % ± 1.3  % to the heterotrophic bacterial carbon demand in the epipelagic layers sampled (sub-surface and DCM). This study clearly reveals potential biases in current and past interpretations of the kinetic parameters for the three enzymes tested based on the fluorogenic-substrate concentration used. In particular, the LAP / βGLU enzymatic ratios and some of the depth-related trends differed between the use of high and low concentrations of fluorogenic substrates. 
PY 2021
PD APR
SO Biogeosciences
SN 1726-4170
PU Copernicus GmbH
VL 18
IS 7
UT 000639027200001
BP 2301
EP 2323
DI 10.5194/bg-18-2301-2021
ID 75452
ER

EF