Marc Garel

Marc Garel
French National Centre for Scientific Research | CNRS · Institut Méditérranéen d'Océanographie (MIO)

PhD

About

75
Publications
10,137
Reads
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761
Citations
Citations since 2016
40 Research Items
571 Citations
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
2016201720182019202020212022020406080100120140
Introduction
I am currently working Microbial Oceanography at Mediterranean Institut of Oceanography. I am focusing my study on hydrostatic pressure effect on deep sea prokaryotes.
Additional affiliations
December 2006 - present
CNRS
Position
  • Engineer
Description
  • High Pressure Device
Education
March 2017 - September 2021
Aix-Marseille Université
Field of study
  • Hyperbaric methods, procedures and techniques for the study of deep-sea microorganisms in in situ conditions
September 2005 - June 2006
Aix-Marseille Université
Field of study
  • Marine Ecology

Publications

Publications (75)
Article
Full-text available
Determining mesopelagic organic carbon budgets is essential to characterize the ocean's role as a carbon dioxide sink. This is because the biological processes observed in the mesopelagic zone are crucial for understanding the biological carbon pump. Yet, field assessments of carbon budgets are often unbalanced with the carbon demand exceeding its...
Preprint
In microbiology, the estimation of the growth rate of microorganisms is a critical parameter to describe a new strain or characterize optimal growth conditions. Traditionally, this parameter is estimated by selecting subjectively the exponential phase of the growth, and then determining the slope of this curve section, by linear regression. However...
Article
Full-text available
The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso- and bathypelagic layers of the ocean (200–4000 m depth). Yet, the abili...
Article
Full-text available
Carbon budgets of hydrothermal plumes result from the balance between carbon sinks through plume chemoautotrophic processes and carbon release via microbial respiration. However, the lack of comprehensive analysis of the metabolic processes and biomass production rates hinders an accurate estimate of their contribution to the deep ocean carbon cycl...
Article
Full-text available
We report on the sub-basin variability in particulate organic carbon (POC) remineralization in the western and central Mediterranean Sea in late spring during the PEACETIME (ProcEss studies at the Air–sEa Interface after dust deposition in the MEditerranean sea) cruise. POC remineralization rates were estimated using the excess biogenic particulate...
Article
Full-text available
In the dark ocean, the balance between the heterotrophic carbon demand and the supply of sinking carbon through the biological carbon pump remains poorly constrained. In situ tracking of the dynamics of microbial degradation processes occurring on the gravitational sinking particles is still challenging. Our particle sinking simulator system (PASS)...
Thesis
The ocean is mostly deep, with most of its volume (>80%) at depths greater than 1000 m, and is poorly sampled (<0.01%). It is characterized by high hydrostatic pressure, low temperature, high inorganic nutrients and low organic carbon concentrations. The input of matter and energy is mainly driven from primary production at the surface in the form...
Article
Full-text available
Plastic garbage patches at the ocean surface are symptomatic of a wider pollution affecting the whole marine environment. Sinking of plastic debris increasingly appears to be an important process in the global fate of plastic in the ocean. However, there is insufficient knowledge about the processes affecting plastic distributions and degradation a...
Article
Full-text available
In piezophilic microorganisms, enzymes are optimized to perform under high hydrostatic pressure. The two major reported mechanisms responsible for such adaptation in bacterial species are changes in amino acids in the protein structure, favoring their activity and stability under high-pressure conditions, and the possible accumulation of micromolec...
Article
Full-text available
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 l...
Article
Full-text available
In the ocean, remineralization rate associated with sinking particles is a crucial variable. Since the 1990s, particulate biogenic barium (Baxs) has been used as an indicator of carbon remineralization by applying a transfer function relating Baxs to O2 consumption (Dehairs's transfer function, Southern Ocean-based). Here, we tested its validity in...
Article
Full-text available
Most of the ocean is deep with the majority of its volume (> 80%) lying under a depth greater than 1000 m. Deep-ocean substrates input is mainly supplied as organic matter (in particulate and/or dissolved forms) by physical and biological processes. Bioavailable dissolved organic carbon (DOC) is mainly consumed in surface water by prokaryotes, whil...
Article
Full-text available
The vertical flux of marine snow particles significantly reduces atmospheric carbon dioxide concentration. In the mesopelagic zone, a large proportion of the organic carbon carried by sinking particles dissipates thereby escaping long term sequestration. Particle associated prokaryotes are largely responsible for such organic carbon loss. However,...
Article
Full-text available
Microorganisms living in deep-oil reservoirs face extreme conditions of elevated temperature and hydrostatic pressure. Within these microbial communities, members of the order Thermotogales are predominant. Among them, the genus Pseudothermotoga is widespread in oilfield-produced waters. The growth and cell phenotypes under hydrostatic pressures ra...
Preprint
Full-text available
We report on the sub-basins variability of particulate organic carbon (POC) remineralization in the central and western Mediterranean Sea during a late spring period (PEACETIME cruise). POC remineralization rates (MR) were estimated using the excess non-lithogenic particulate barium (Baxs) inventories in mesopelagic waters (100–1000 m) and compared...
Preprint
Full-text available
In the ocean, remineralisation rate associated with sinking particles is a crucial variable. Since the 90's, particulate biogenic barium (Baxs) has been used as an indicator of carbon remineralization by applying a transfer function relating Baxs to O2 consumption (Dehairs's transfer function, Southern Ocean-based). Here, we tested its validity in...
Preprint
Full-text available
Prokaryotic ectoenzymatic activity, abundance and heterotrophic production were determined in the Mediterranean Sea, within the epipelagic and the upper part of the mesopelagic layers. The Michaelis-Menten kinetics were assessed, using a range of low (0.025 to 1 µM) and high (0.025 to 50 µM) concentrations of fluorogenic substrates. Thus, Km and Vm...
Presentation
Deep ocean, poorly sampled (< 0.01%), is characterized by high hydrostatic pressure, low temperature, high inorganic nutrients and low organic carbon concentrations. Measurements of metabolic activities of bathypelagic prokaryotes are generally underestimated due to the technological limitations in recovering samples and maintaining them under in s...
Article
Full-text available
Rock-hosted subseafloor habitats are very challenging for life, and current knowledge about microorganisms inhabiting such lithic environments is still limited. This study explored the cultivable microbial diversity in anaerobic enrichment cultures from cores recovered during the International Ocean Discovery Program (IODP) Expedition 357 from the...
Article
Full-text available
The pelagic realm of the dark ocean is characterized by high hydrostatic pressure, low temperature, high-inorganic nutrients, and low organic carbon concentrations. Measurements of metabolic activities of bathypelagic bacteria are often underestimated due to the technological limitations in recovering samples and maintaining them under in situ envi...
Data
Top end cap with optic measurement. (1) Optic fiber, (2) Temperature sensor (pt100), (3) Inlet/outlet 1/8″ diameter (3.2 mm O.D.), (4) O'ring, (5) Planar optode (diameter 5 mm), (6) Sapphire window, (7) Titanium screw. This modified top end-cap can be fitted indifferently on TA6V HPBs or on 316L stainless-steel with PEEK coating HPBs. However, the...
Data
RNA:DNA ratios from RNA-based and DNA-based relative log transformed abundance of OTU. This ratio enables us to estimate a proportion of active prokaryote for each sample. The black line is 1:1 bar. OTU are distributed around the line which indicates that the microbial communities identified in the sample are also active.
Data
An animated diagram showing a transfer in equi-pressure mode between two High-Pressure Bottles (HPBs). HPB1 is the high-pressure bottle containing the 3,000 m-depth sample maintained under in situ pressure conditions. HPB2 is the high-pressure bottle containing radiolabeled compounds, such as, 3H-Leucine to measure prokaryotic heterotrophic product...
Data
Schematic drawing of sampling valve fitted on High-Pressure Sampler Unit (HSU). 1. Nylon wire; 2. Stainless-steel trigger; 3. Stainless-steel frame for valve; 4. Modified swagelock valve (réf: SS-84PS4); 5. Modified handle to link trigger at spring; 6. sample inlet, 7. spring. In this view sampling valve is set in close position before sampling (A)...
Data
Photograph showing different point of view of the mobile MIO-HPLab container. This mobile laboratory has been constructed in a 20 feet container. It is composed of two piloted pressure genrators (PPGs), four temperature regulated water baths with two temperature coolers dedicated for High-Pressure Sampler Unit (HPSU) and particle sinking experiment...
Data
Animated schematic drawing in transparency of the front and back views of the High-Pressure Sample Unit (HPSU). (A) During the descent of the CTD-carousel. The inlet-valve is in close position; (B) During the sampling at the chosen depth after firing the CTD-Carousel and the inlet-valve is in open position. The numbers are the same than in Figure 1...
Article
Full-text available
Bacterial-bioluminescence regulation is often associated with quorum sensing. Indeed, many studies have been made on this subject and indicate that the expression of the light-emission-involved genes is density-dependent. However, most of these studies have concerned two model species, A. fischeri and V.campbellii. Very few works have been done on...
Data
Primer sequences and features of the target genes in P. phosphoreum ANT2200, used in RT-qPCR.
Poster
Full-text available
De fortes périodes d'activité lumineuse ont été mises en évidence principalement en 2010, coïncidant avec des changements environnementaux majeurs, Martini et al. (in prep.). Un ensemble d'autres variables environnementales non enregistrées sur le site ANTARES pourraient également entrer en jeu dans ce phénomène. Objectifs : Observation et quantifi...
Article
Full-text available
In the deep ocean, fluxes of particulate organic carbon (POC) and calcium carbonate are positively correlated, suggesting that CaCO3 could increase sinking particle densities and/or protect the organic matter from degradation by prokaryotes, the so called “ballast effect”. Here, we used the PArticle Sinking Simulator (PASS) system to investigate th...
Article
Full-text available
Gorgonian corals are among the most representative species of hard-bottom sublittoral ecosystems in the Mediterranean Sea. The red gorgonian, Paramuricea clavata, harbors a specific, spatially and temporally stable bacterial community that may have an important biological role in the function of the holobiont. However, little is known about the mic...
Article
Full-text available
Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantial eco-physiological diversity including free-living, symbiotic and piezophilic life styles. Genomic characteristics underlying this variability across species are poorly understood. Here we carried out genomic and physiological analysis of Photobacterium phosphoreum...
Article
Full-text available
Open-ocean convection is a fundamental process for thermohaline circulation and biogeochemical cycles that causes spectacular mixing of the water column. Here, we tested how much the depth-stratified prokaryotic communities were influenced by such an event, and also by the following re-stratification. The deep convection event (0-1500m) that occurr...
Article
Full-text available
The central Mediterranean Sea is among the most oligotrophic habitats in the marine environment. In this study, we investigated the abundance, diversity and activity of prokaryoplankton in the water column (25–3000-m depth) at Station Vector (Tyrrhenian Sea, 39°32.050′ N; 13°22.280′ E). This specific water column consists of three different water m...
Article
Full-text available
RNA-seq was used to study the response of Desulfovibrio hydrothermalis, isolated from a deep-sea hydrothermal chimney on the East-Pacific Rise at a depth of 2,600 m, to various hydrostatic pressure growth conditions. The transcriptomic datasets obtained after growth at 26, 10 and 0.1 MPa identified only 65 differentially expressed genes that were d...
Article
Full-text available
Bacteria of the genus Photobacterium thrive worldwide in oceans and show substantially varied lifestyles, including free-living, commensal, pathogenic, symbiotic, and piezophilic. Here, we present the genome sequence of a luminous, piezophilic Photobacterium phosphoreum strain, ANT-2200, isolated from a water column at 2,200 m depth in the Mediterr...
Article
Full-text available
Bacterial bioluminescence is commonly found in the deep sea and depends on environmental conditions. Photobacterium phosphoreum ANT-2200 has been isolated from the NW Mediterranean Sea at 2200-m depth (in situ temperature of 13uC) close to the ANTARES neutrino telescope. The effects of hydrostatic pressure on its growth and luminescence have been i...
Data
Representation of growth curves for temperatures of 4, 13, 20, 30 and 37°C and for pressure of 0.1, 10, 22, 30, and 40 MPa. The logistic model (line) improves the r and K parameter estimation on empirical growth data (dots). Dashed lines are levels of confidence for the 0.05 and 0.95 quantile curves and the 0.25 and 0.75 quantile curves. The growth...
Data
Phenotypic and enzymatic characterizations of P. phosphoreum strain ANT-2200. The presence of cytochrome oxidase was tested with one- or two-days cultures on SWC medium, using filter papers dropped with 1% N, N-dimethyl-p-phenylene-diamine hydrochloride (Kovacs oxidase test). Catalase activity was determined by looking at bubble production in a 3%...
Article
Effects of hydrostatic pressure on pure cultures of prokaryotes have been studied extensively but impacts at the community level in the ocean are less well defined. Here we consider hydrostatic pressure effects on natural communities containing both unadapted (piezosensitive) prokaryotes originating from surface water and adapted (including piezoph...
Article
Full-text available
Desulfovibrio piezophilus strain C1TLV30(T) is a piezophilic anaerobe that was isolated from wood falls in the Mediterranean deep-sea. D. piezophilus represents a unique model for studying the adaptation of sulfate-reducing bacteria to hydrostatic pressure. Here, we report the 3.6 Mbp genome sequence of this piezophilic bacterium. An analysis of th...
Data
Frequency distribution of the COG categories between D. piezophilus and selected Desulfovibrio genomes. For each organism, COG category with a proportion away from the 2 SDs of the mean of other three organisms is considered as a significant difference and is marked by a star (red star, >2 SD; black star, <2 SD). (TIF)
Data
Full-text available
List of the 53 COGs present in D. piezophilus and P. profundum but absent in the non-piezophilic D. vulgaris Hildenborough and D. salexigens strains. (PDF)
Data
Phylogenetic analysis of genes DESPIv2_11220 (A), DESPIv2_11837 (B). The 20 best BLAST hit proteins versus nr were retrieved from Genbank. The phylogenetic reconstruction was achieved on the trimmed alignment using PhyML with a WAG matrix. Branch support estimated using a bootstrap of 100. (TIF)
Data
16S RNA based Phylogenetic tree of Desulfovibrio strains. (TIF)
Data
Full-text available
The putative genomic islands in D. piezophilus genome. (PDF)
Data
List of genes encoding proteins involved in energy metabolism. (PDF)
Data
Full-text available
The genomic islands in Desulfovibrio species. (PDF)
Data
Supplemental information on Materials and Methods. (DOC)
Data
Full-text available
Gene expression levels by qRT-PCR. (PDF)
Data
Full-text available
Average GC and GC3 content of genomes in this study and strains characteristics. (PDF)
Data
Full-text available
The 347 genes with no homologs in sulfate reducers. (PDF)
Data
Full-text available
List of oligonucleotide primers used. (PDF)
Conference Paper
Full-text available
Dissolved organic carbon (DOC) is divided into three reservoirs of different reactivities (labile, semi-labile and non-reactive). The contribution of the semi-labile DOC to the global prokaryotic production has been assessed in very few previous studies. Interestingly enough some experiments show rapid utilization of semi-reactive DOC by prokaryote...
Article
This study examined total uptake of extracellular polymeric substances (EPS) and glucose and the percentage of prokaryotic cells (Bacteria, Crenar-chaea and Euryarchaea) consuming these com-pounds in the major water masses at the DYFAMED site (NW Mediterranean Sea). The potential assimila-tion rates of EPS at 10 m depth were higher but on the same...