Olivier Gros

Olivier Gros
University of the French Antilles | Reunion · Department of Biology

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127
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Publications

Publications (127)
Article
Full-text available
Symbiotic interactions drive species evolution, with nutritional symbioses playing vital roles across ecosystems. Chemosynthetic symbioses are globally distributed and ecologically significant, yet the lack of model systems has hindered research progress. The giant ciliate Zoothamnium niveum and its sulfur-oxidizing symbionts represent the only kno...
Preprint
Symbiotic interactions drive species evolution, with nutritional symbioses playing vital roles across ecosystems. Chemosynthetic symbioses are globally distributed and ecologically significant, yet the lack of model systems has hindered research progress. The giant ciliate Zoothamnium niveum and its sulfur-oxidizing symbionts represent the only kno...
Article
Full-text available
Aratus pisonii and Minuca rapax are two brachyuran crabs living with bacterial ectosymbi-onts located on gill lamellae. One previous study has shown that several rod-shaped bacterial mor-photypes are present and the community is dominated by Alphaproteobacteria and Bacteroidota. This study aims to identify the mode of transmission of the symbionts...
Article
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Biofilm-forming cyanobacteria are abundant in mangrove ecosystems, colonizing various niches including sediment surface and periphyton where they can cover large areas, yet have received limited attention. Several filamentous isolates were recently isolated from Guadeloupe, illustrating the diversity and novelty present in these biofilms. In this s...
Article
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Bacteria and Archaea are traditionally regarded as organisms with a simple morphology constrained to a size of 2–3 µm. Nevertheless, the history of microbial research is rich in the description of giant bacteria exceeding tens and even hundreds of micrometers in length or diameter already from its early days, for example, Beggiatoa spp., to the pre...
Article
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Free-living amoebae (FLA) are ubiquitous protozoa mainly found in aquatic environments. They are well-known reservoirs and vectors for the transmission of amoeba-resistant bacteria (ARB), most of which are pathogenic to humans. Yet, the natural bacterial microbiota associated with FLA remains largely unknown. Herein, we characterized the natural ba...
Article
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Mangrove sediments are known to be potentially active reducing zones for nitrogen removal. The goal of this work was to investigate the potential for nitrate reduction in marine mangrove sediments along a canal impacted by anthropogenic activity (Guadeloupe, Lesser Antilles). To this end, the effect of nitrate concentration, organic carbon load, an...
Article
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Thiovulum spp. (Campylobacterota) are large sulfur bacteria that form veil-like structures in aquatic environments. The sulfidic Movile Cave (Romania), sealed from the atmosphere for ~5 million years, has several aqueous chambers, some with low atmospheric O 2 (~7%). The cave’s surface-water microbial community is dominated by bacteria we identifie...
Article
Full-text available
Ehrlichia ruminantium is an obligate intracellular bacterium, transmitted by ticks of the genus Amblyomma and responsible for heartwater, a disease of domestic and wild ruminants. High genetic diversity of E. ruminantium strains hampers the development of an effective vaccine against all strains present in the field. In order to develop strategies...
Article
Full-text available
Huanglongbing (HLB) is a disease that is responsible for the death of millions of trees worldwide. The bacterial causal agent belongs to Candidatus Liberibacter spp., which is transmitted by psyllids. The bacterium lead most of the time to a reaction of the tree associated with callose synthesis at the phloem sieve plate. Thus, the obstruction of p...
Article
Secondary metabolites are bioactive compounds produced by living organisms that can be indicative of symbiotic relationships in nature. Prior studies have demonstrated putative symbiotic interactions between decapod crabs and epibiotic bacteria in their environment. This study presents a sample preparation protocol for metabolomics analysis of lyop...
Article
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Wolbachia Hertig, 1936 is an intracellular bacterial symbiont colonizing many arthropods. Of the studies done on the bacteria present in the superfamily Gerroidea Leach, 1815, no report of Wolbachia infection had yet been made. Thus, we checked the presence of Wolbachia in six Gerroidea species which colonize tropical aquatic environments by PCR us...
Article
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Cells of most bacterial species are around 2 micrometers in length, with some of the largest specimens reaching 750 micrometers. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized Candidatus ( Ca. ) Thiomargarita magnifica, a bacterium that has an average cell length greater than 9000 micromet...
Preprint
Full-text available
Cells of most bacterial species are around 2 µm in length, with some of the largest specimens reaching 750 µm. Using fluorescence, x-ray, and electron microscopy in conjunction with genome sequencing, we characterized Ca. Thiomargarita magnifica, a bacterium with an average cell length greater than 9,000 µm that is visible to the naked eye. We foun...
Article
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Less than a handful of cuboid and squared cells have been described in nature which makes them a rarity. Here, we show how Candidatus Thiosymbion cuboideus, a cube-like gammaproteobacterium, reproduces on the surface of marine free-living nematodes. Immunostaining of symbiont cells with an anti-fimbriae antibody revealed that they are host-polarize...
Preprint
Full-text available
Mangrove sediments are generally nitrogen limited, with nitrate reduction to ammonium instead of denitrification in these sediments, resulting in nitrogen retention rather than nitrogen elimination. The goal of this work was to investigate the potential for nitrate reduction in marine mangrove sediments along a canal impacted by anthropogenic activ...
Article
Full-text available
A large (47.75 ± 3.56 µm in diameter) Thiovulum bacterial strain forming white veils is described from a marine mangrove ecosystem. High sulfide concentrations (up to 8 mM of H2S) were measured on sunken organic matter (wood/bone debris) under laboratory conditions. This sulfur-oxidizing bacterium colonized the organic matter, forming a white veil....
Article
Full-text available
Huanglongbing (HLB) is presently a major threat to the citrus industry. Because of this disease, millions of trees are currently dying worldwide. The putative causal agent is a motile bacteria belonging to Candidatus Liberibacter spp., which is transmitted by psyllids. The bacteria is responsible for the synthesis of callose at the phloem sieve pla...
Article
We describe here the interactions between bacterial ectosymbionts and two Caribbean mangrove crabs: Aratus pisonii (Sesarmidae) and Minuca rapax (Ocypodidae). Specimens of A. pisonii and M. rapax were collected in Guadeloupe from mangrove trees (Rhizophora mangle) and from the mangrove mud, respectively. Ectosymbionts colonizing gills in all host i...
Article
Full-text available
Significance Knowledge of host–symbiont biogeography is critical to understanding fundamental aspects of symbiosis such as host–symbiont specificity. Marine animals typically acquire their symbionts from the environment, a strategy that enables the host to associate with symbionts that are well-suited to local conditions. In contrast, we discovered...
Article
This study aims to illustrate distribution of semiaquatic bug species in Guadeloupe (Lesser Antilles), as there is still little knowledge about the biodiversity of the island’s mangroves. In addition to Limnogonus franciscanus Stål, 1859 Stål, C. (1859), ‘Hemiptera. in: Fregatten Eugenies Resa, 1851-1853’, Zoologie, 4, 219–298. [Google Scholar] and...
Preprint
Full-text available
Ehrlichia ruminantium is an obligate intracellular bacterium, transmitted by ticks of the genus Amblyomma and responsible for heartwater, a disease of domestic and wild ruminants. High genetic diversity of E. ruminantium strains hampers the development of an effective vaccine against all strains present in the field. In order to develop strategies...
Article
Full-text available
The goals of this study were to evaluate growth, development, and calcification process of veligers of Strombus gigas grown in natural conditions in mesocosm versus laboratory conditions. In this study, larvae bred in mesocosm conditions had a good growth rate (33.3±12.40 μm.day−1) when fed with natural phytoplankton in natural flowing seawater ver...
Article
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Abstract Chlordecone (CLD) levels measured in the rivers of the French West Indies were among the highest values detected worldwide in freshwater ecosystems, and its contamination is recognised as a severe health, environmental, agricultural, economic, and social issue. In these tropical volcanic islands, rivers show strong originalities as simplif...
Article
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Benthic cyanobacteria strains from Guadeloupe have been investigated for the first time by combining phylogenetic, chemical and biological studies in order to better understand the taxonomic and chemical diversity as well as the biological activities of these cyanobacteria through the effect of their specialized metabolites. Therefore, in addition...
Poster
This proposal presents a pedagogical approach in which context effects are used in the teaching of environmental sciences. Within the project «Educational Technology for Contextual Teaching TEEC» - Technologies Éducatives pour l'Enseignement en Contexte – https://teec.teluq.ca/en/), this pedagogy has been tested at an international level. The princ...
Article
The queen conch, Strombus gigas (Linnaeus, 1758), is a marine mollusc of ecological and economic importance in the Caribbean. Its populations are declining due to overexploitation. We describe ontogenesis of the digestive gland in S. gigas during the larval stages. Larvae were studied over a period of 42 d in laboratory culture, from eggs to crawli...
Article
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Crypt cells—one of the three cell types composing Strombidae digestive tubules—are characterized by the presence of numerous metal-containing phosphate granules termed spherocrystals. We explored the bioaccumulation and detoxification of metals in Strombidae by exposing wild fighting conch Strombus pugilis for 9 days to waterborne CuSO4 and ZnSO4....
Article
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Here, we report the first description of a marine purple sulfur bacterium (PSB) from sulfide-rich sediments of a marine mangrove in the Caribbean. TEM shows that this new isolate contains intracytoplasmic vesicular membrane systems (containing bacteriochlorophyll a) and larger internal sulfur granules, confirmed by EDXS analyses performed using ESE...
Article
The management of banana postharvest conditions is a pre-requisite for adapting the storage, shipping and gassing conditions to the specific physiology of individual hybrid bananas. The cultivar ‘CIRAD 925’, developed by CIRAD, is a good case study for adapting banana food chain conditions to accommodate the specificities of this hybrid. Indeed, th...
Article
Ciliates represent a diversified group of protists known to establish symbioses with prokaryotic micro-organisms. They are mainly phagotrophs and symbiotic relationships with bacteria can give them an important advantage in chemosynthetic environments. The aim of this study is to describe the thiotrophic association that occurs between the peritric...
Article
Here, the first description is reported of an epsilon sulfur-oxidizing bacterium from sulfide-rich sediments of marine mangrove in the Caribbean. By transition electron microscopy it was shown that this new strain contains intracytoplasmic large internal sulfur granules, which was confirmed by energy-dispersive X-ray spectroscopy analyses performed...
Article
Full-text available
Purpose Marine mangrove sediments in the Manche-à-Eau lagoon (Guadeloupe, Caribbean Sea) harbor locally extensive, white microbial mats. These mats cover the surface of reduced sediments near the roots of red mangrove trees, Rhizophora mangle, and are mainly composed of sulfur-oxidizing bacteria belonging to the Beggiatoaceae family, with some fila...
Article
A novel spiro-indolofuranone fused to a thiazine skeleton, orbicularisine (1), was isolated from gills of the mollusk Codakia orbicularis. The isolation and structure elucidation using spectroscopic evidence including mass and NMR spectroscopy are described. The final structure of 1 was supported by key HMBC correlation.
Article
The biogeochemistry of sulfur and carbon during early-diagenetic processes within organic-rich marine mangrove sediments was studied in the “Manche à Eau” lagoon, Guadeloupe, West Indies. These sediments are characterized by a total organic carbon content (TOC) mostly above 11 wt%, δ¹³CTOC below − 25‰ VPDB and C/Nmolar ratios exceeding 15. Rates of...
Article
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Objective The first aim of this study was to evaluate the antimicrobial resistance of Enterobacteriaceae in different water environments of Guadeloupe and especially those impacted by waste water treatment plants (WWTP) effluents. The second objective was to characterize the genetic basis for antibiotic resistance of extended-spectrum beta-lactamas...
Article
Full-text available
The shallow water bivalve Codakia orbicularis lives in symbiotic association with a sulfur-oxidizing bacterium in its gills. The endosymbiont fixes CO2 and thus generates organic carbon compounds, which support the host's growth. To investigate the uncultured symbiont's metabolism and symbiont-host interactions in detail we conducted a proteogenomi...
Article
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Peel splitting is a major physiological disorder affecting post-harvest banana quality. This phenomenon occurs only 3–6 days after ripening induction in specific cultivars such as cv. 925 when stored in saturating humidity conditions. In these conditions, Cavendish cultivars (Grande Naine, cv. GN) are not susceptible to splitting. Cvs. 925 and GN w...
Poster
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Few diatoms and other microorganisms observed in West Frensh Indies thermal springs
Article
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In chemoautotrophic associations, sequence comparison of 16S rRNA has been the method of choice to study bacterial diversity in the context of host/symbiont coevolution. However, the relative low rate of evolution of 16S rRNA has been shown to result in a diminished capacity to discriminate between closely related bacterial strains or species. With...
Article
Seven individuals of a single morphotype of mussels (Bivalvia: Mytilidae) were found attached to a naturally sunken whale intervertebral disk collected in Guadeloupe (Caribbean) at 800 m depth. These specimens resemble small Idas mussels which are found worldwide at cold seeps and hydrothermal vents, and typically harbor ectosymbiotic bacteria on t...
Article
Full-text available
Banana has been a main agricultural product in the French West Indies (Guadeloupe and Martinique) since the 1960s. This crop requires the intensive use of pesticides to prevent attacks by insect pests. Chlorinated pesticides, such as hexachlorocyclohexane (HCH), chlordecone and dieldrin, were used until the beginning of the 1990s, resulting in a ge...
Article
Full-text available
The organogenesis, histogenesis and growth of larvae of the fighting conch Strombus pugilis (Linné, 1758) were studied over a period of 30 d after hatching in laboratory culture. Early development of S. pugilis was examined by light and scanning electron microscopy. Rearing was conducted at 27 ± 1 °C. Veligers were reared at 200 larvae l−1 in 4-l c...
Article
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http://mollus.oxfordjournals.org/cgi/content/abstract/eyv011? ijkey=wN63ugdccwM8mx4&keytype=ref
Article
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Since the discovery of thioautotrophic bacterial symbiosis in the giant tubeworm Riftia pachyptila, there has been great impetus to investigate such partnerships in other invertebrates. In this study, we present the occurrence of a sulphur-oxidizing symbiosis in a metazoan belonging to the phylum Cnidaria in which this event has never been describe...
Article
Full-text available
The outer membrane proteins (OMPs) of Gram-negative bacteria play a crucial role in virulence and pathogenesis. Identification of these proteins represents an important goal for bacterial proteomics, because it aids in vaccine development. Here, we have developed such an approach for Ehrlichia ruminantium, the obligate intracellular bacterium that...
Article
Full-text available
Beggiatoaceae, giant sulphur-oxidizing bacteria, are well known to occur in cold and temperate waters, as well as hydrothermal vents, where they form dense mats on the floor. However, they have never been described in tropical marine mangroves. Here, we describe two new species of benthic Beggiatoaceae colonizing a marine mangrove adjacent to mangr...
Article
Full-text available
Large filamentous sulfur-oxidizing bacteria belonging to the Beggiatoacae family can cover large portions of shallow marine sediments surrounding mangroves in Guadeloupe (French West Indies). In order to assess the importance of Beggiatoa mats as an infaunal food source, observations were conducted of the area within mats and at increasing distance...
Article
The Caribbean bivalves Codakia orbicularis (Linné, 1758) and C. orbiculata (Montagu, 1808) live in seagrass beds of Thalassia testudinum and harbor intracellular sulfur-oxidizing gamma-proteobacteria. These bacterial symbionts fix CO2 via the Calvin Benson cycle and provide organic compounds to the bivalve. During experimentally induced starvation,...
Article
In this multidisciplinary study, we combined morphological, physiological and phylogenetic approaches to identify three dominant water-bloom-forming cyanobacteria in a tropical marine mangrove in Guadeloupe (French West Indies). Phylogenetic analysis based on 16S rRNA gene sequences place these marine cyanobacteria in the genera Oscillatoria (Oscil...
Article
Up to date, the culture of sulphur-oxidizing bacterial symbionts associated with marine invertebrates remains impossible. Therefore few studies focused on symbiont's physiology under stress conditions. In this study, we carried out a comparative experiment based on two different species of lucinid bivalves (Codakia orbiculata and Lucina pensylvanic...
Article
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Haplognathia ruberrima is a cosmopolitan gnathostomulid species found in sulfur bacterial mats in mangroves in Guadeloupe (French West Indies). Haplo-gnathia ruberrima presents a d 13 C value lower than all measured meiofaunal grazers and lower than the available measured food sources of this environment. This low d 13 C value can not be due to spe...
Article
Abstract Cold seeps have recently been discovered in the Nile deep-sea fan (Eastern Mediterranean), and data regarding associated fauna are still scarce. In this study, two bivalve species associated with carbonate crusts and reduced sediment are identified based on sequence analysis of their 18S and 28S rRNA-encoding genes, and associated bacteria...
Article
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The giant bathymodioline mussels from vents have been studied as models to understand the adaptation of organisms to deep-sea chemosynthetic environments. These mussels are closely related to minute mussels associated to organic remains decaying on the deep-sea floor. Whereas biological data accumulate for the giant mussels, the small mussels remai...
Article
Wood debris are an important component of mangrove marine environments. Current knowledge of the ecological role of wood falls is limited by the absence of information on metazoan colonization processes over time. The aim of this study was to provide insights to their temporal dynamics of wood eukaryotic colonization from a shallow water experiment...
Article
Full-text available
Strombus gigas and Strombus pugilis are threatened species and aquaculture represents a good alternative solution to the fishing. In this study, we highlighted the intracellular digestion process in the digestive gland of two Strombidae species, S. gigas and Strombuspugilis, by the cytochemical characterization of two lysosomal enzymes: acid phosph...
Article
The shallow-water bivalve Codakia orbiculata which harbors gill-endosymbiotic sulfur-oxidizing γ-proteobacteria can lose and acquire its endosymbionts throughout its life. Long-term starvation and recolonization experiments led to changes in the organization of cells in the lateral zone of gill filaments. This plasticity is linked to the presence o...
Article
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Sphaeroma serratum is a marine isopod species that inhabits seashores from Europe to West Africa. The individuals live under stones in direct contact with reduced sediments and harbour a diverse bacterial community on the cuticle of their pleopods. We investigated the diversity of these epibiotic bacteria on male (pubescent and senescent) and femal...
Article
In marine invertebrates that acquire their symbionts from the environment, these are generally only taken up during early developmental stages. In the symbiosis between lucinid clams and their intracellular sulfur-oxidizing bacteria, it has been shown that the juveniles acquire their symbionts from an environmental stock of free-living symbiont for...
Article
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Digestive tubules of Strombidae are composed by three cell types: digestive cells, vacuolated cells, and crypt cells. The last one is characterized by the presence of intracellular granules identified as spherocrystals. Such structures are known to occur in basophilic cells of gastropod digestive gland, where they are supposed to be involved in the...