About
200
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Introduction
Cécile Bernard currently works at the UMR 7245 CNRS / MNHN : Molécules de Communication et Adaptation des Micro-organismes, Muséum National d'Histoire Naturelle. Cécile does research in Ecotoxicology, Ecology, Limnology and Microbiology.
Additional affiliations
January 2009 - December 2011
January 2007 - present
January 1997 - present
Publications
Publications (200)
Anthropogenic perturbations profoundly affect aquatic ecosystem microbiomes and associated ecological functions. Comparatively, the effects of geological stresses on microbiome composition and stability remain poorly explored. Here, we monitored the archaeal, bacterial and microeukaryotes community structure over an 8-years period in Lake Dziani Dz...
With more than 12 million inhabitants, the Greater Paris offers a natural laboratory to explore the effects of eutrophication on freshwater lakes within a relatively restricted area. Here, a four-month time-series was carried out during summertime to monitor planktonic microbial communities of nine lakes located within a 70 km radius around Paris (...
Saline-alkaline lakes often shelter high biomasses despite challenging conditions, owing to the occurrence of highly adapted phototrophs. Dziani Dzaha (Mayotte) is one such lake characterized by the stable co-dominance of the cyanobacterium Limnospira platensis and the picoeukaryote Picocystis salinarum throughout its water column. Despite light pe...
Limnospira can colonize a wide variety of environments ( e.g., freshwater, brackish, alkaline or alkaline-saline water) and develop dominant and even permanent blooms that limit over-shadowed adjacent phototrophs diversity, especially in alkaline and saline environments. Previous phylogenomic analysis of Limnospira allowed us to distinguish two maj...
Given the increasing eutrophication of water bodies in Africa due to increasing anthropogenic pressures, data are needed to better understand the responses of phytoplankton communities to these changes in tropical lakes. These ecosystems are used by local human populations for multiple purposes, including fish and drinking water production, potenti...
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...
Microorganisms are key contributors of aquatic biogeochemical cycles but their microscale ecology remains largely unexplored, especially interactions occurring between phytoplankton and microorganisms in the phycosphere, that is the region immediately surrounding phytoplankton cells. The current study aimed to provide evidence of the phycosphere ta...
In comparison with northern countries, limited data are available on the occurrence and potential toxicity of cyanobacterial blooms in lakes and ponds in sub-Saharan countries. With the aim of enhancing our knowledge on cyanobacteria and their toxins in Africa, we performed a 17-month monitoring of a freshwater ecosystem, Lagoon Aghien (Ivory Coast...
Aims:
The cyanobacterial genus, Limnospira (anc. Arthrospira Stizenberger ex Gomont 1892), commonly called 'Spirulina', is widely used for commercial purposes because of its high protein content and beneficial probiotic metabolites. Thus, the taxonomy of this genus is important because of its consequences for food applications.
Methods and result...
Introduction
Cyanobacteria are important members of the dense biofilms that colonize available substrates in mangrove habitats worldwide. However, their taxonomic diversity and biological activities have received little attention.
Methods
The occurrence of cyanobacteria is evaluated in 27 biofilms collected from mangroves in Mayotte. Filamentous c...
Cyanobacteria are oxygenic photosynthetic bacteria that perform a substantial part of the global primary production. Some species are responsible for catastrophic environmental events, called blooms, which have become increasingly common in lakes and freshwater bodies as a consequence of global changes. Genotypic diversity is considered essential f...
https://theconversation.com/dans-les-eaux-de-baignade-les-cyanobacteries-amies-ou-ennemies-204352
In comparison with northern countries, limited data are available on the occurrence and potential toxicity of cyanobacterial blooms in lakes and ponds in Sub-Saharan countries. With the aim of enhancing our knowledge on cyanobacteria and their toxins in Africa, we performed a 17-month monitoring of a freshwater ecosystem, Lagoon Aghien (Ivory Coast...
Bloom-forming phytoplankton dynamics are still unpredictable, even though it is known that several abiotic factors, such as nutrient availability and temperature, are key factors for bloom development. We investigated whether biotic factors, i.e. the bacterioplankton composition (via 16SrDNA metabarcoding), were correlated with phytoplankton dynami...
The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom‐forming cyanobacterium found worldwide in freshwater ecosystems. If iACC‐forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here we...
Cyanobacteria constitute a pioneer colonizer of specific environments for whom settlement in new biotopes precedes the establishment of composite microbial consortia. Some heterotrophic bacteria constitute cyanobacterial partners that are considered as their cyanosphere, being potentially involved in mutualistic relationships through the exchange a...
Africa’s water needs are often supported by eutrophic water bodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake wa...
Cyanobacteria constitute pioneer colonizer of specific environments whom settlement in new biotopes precedes the establishment of composite microbial consortia. Some heterotrophic bacteria constitute cyanobacterial partners that are considered as their cyanosphere, being potentially involved in mutualistic relationships through exchange and recycli...
Aghien lagoon (Ivory Coast) is a eutrophic freshwater lagoon that harbors high biomasses of phytoplankton. Despite Increasing interest in fish gut microbiomes diversity and functions, little data is currently available regarding wild species from tropical west African lakes. Here, gut-associated bacterial communities are investigated in four fish s...
Cyanobacterial blooms can modify the dynamic of aquatic ecosystems and have harmful consequences for human activities. Moreover, cyanobacteria can produce a variety of cyanotoxins, including microcystins, but little is known about the role of environmental factors on the prevalence of microcystin producers in the cyanobacterial bloom dynamics. This...
Africa’s water needs are often supported by eutrophic waterbodies dominated by cyanobacteria posing health threats to riparian populations from cyanotoxins, and Lake Victoria is no exception. In two embayments of the lake (Murchison Bay and Napoleon Gulf), cyanobacterial surveys were conducted to characterize the dynamics of cyanotoxins in lake wat...
Given the increasing eutrophication of water bodies in Africa due to increasing anthropogenic pressures, data are needed to better understand the responses of phytoplankton communities to these changes in tropical lakes. These ecosystems are used by local human populations for multiple purposes, including fish and drinking water production, potenti...
Given the increasing eutrophication of water bodies in Africa due to increasing anthropogenic pressures, data are needed to better understand the responses of phytoplankton communities to these changes in tropical lakes. These ecosystems are used by local human populations for multiple purposes, including fish and drinking water production, potenti...
Abstract
Cyanobacteria and eukaryotic microalgae are key players in life on Earth. They have adapted to a broad diversity of ecosystems, and ensure roughly half of the primary production. Their study requires strains to be isolated, deposited and maintained ex situ in collections, and made available to the scientific community along with expert kno...
Cyanobacteria and eukaryotic microalgae are key players in life on Earth. They have adapted to a broad diversity of ecosystems, and ensure roughly half of the primary production. Their detailed study greatly benefits from isolated strains, deposited and maintained ex situ in culture collections, and made available to the scientific community along...
Nitrogen isotope compositions (δ¹⁵N) in sedimentary rocks are extensively used to investigate the biogeochemical nitrogen cycle through geological times. This use relies on the observation that, in modern continental platforms and anoxic basins, surface sediments faithfully record the δ¹⁵N of primary producers, assuming that it was similar in the p...
Understanding the role of microbial interactions in the functioning of natural systems is often impaired by the levels of complexity they encompass. In this study, we used the relative simplicity of an hypersaline crater lake hosting only microbial organisms (Dziani Dzaha) to provide a detailed analysis of the microbial networks including the three...
The “cyanobacteria and microalgae” collection of the Muséum national d'Histoire naturelle includes, respectively, 870 and 890 living strains maintained in the laboratory. This collection supports fundamental research, particularly in taxonomy and ecophysiology, but also numerous activities for the development of bioactive molecules and expertise in...
Cyanobacteria are microorganisms able to adapt to a wide variety of environmental conditions and abiotic stresses. They produce a large number of metabolites that can participate in the dynamic adaptation of cyanobacteria to a range of different light, temperature, and nutrient conditions. Studying the metabolite profile is one way to understand ho...
Studies on microbial communities, and their associated organic biomarkers, that are found thriving in the aphotic euxinic waters in modern stratified ecosystems are scarce compared to those undertaken in euxinic photic zones. The Dziani Dzaha (Mayotte, Indian Ocean) is a tropical, saline, alkaline crater lake that has recently been presented as a m...
Cyanobacteria are microorganisms able to adapt to a wide variety of environmental conditions and abiotic stresses. They produce a very large number of metabolites that can participate in the adaptation of cyanobacteria to a large range of resources such as light, temperature, or nutrient. The metabolites variation is one way to understand the physi...
La collection de cyanobactéries et microalgues du Muséum national d’Histoire naturelle comprend respectivement 870 et 890 souches vivantes maintenues au laboratoire. Elle s’enrichit régulièrement, notamment dans le cadre de programmes de recherche menés en France et à l’étranger. Cette collection est le support d’une recherche fondamentale, notamme...
Background: Genotypic diversity within cyanobacteria populations, partly driven by horizontal gene transfers, is a key factor of their colonization success, allowing them to cope with spatio-temporal fluctuations of the environmental conditions. By providing complementary functions, such as oxidative stress protection, heterotrophic bacteria compos...
The supply of drinking water is a vital challenge for the people who live on the African continent, as this continent is experiencing strong demographic growth and therefore increasing water demands. To meet these needs, surface water resources are becoming increasingly mobilized because underground resources are not always available or have alread...
Cyanobacteria are able to synthesize a high diversity of natural compounds that account for their success in the colonization of a variety of ecological niches. Many of them have beneficial properties. The mud from the thermal baths of Balaruc-Les-Bains, one of the oldest thermal baths in France, has long been recognized as a healing treatment for...
Eutrophication of Lake Victoria led to changes in its phytoplankton communities. However, different levels of eutrophication exist in the open lake and the bays, and between embayments. This study utilized spatial and temporal sampling of Napoleon Gulf and Murchison Bay, exhibiting different trophic conditions. Over one year, we investigated phytop...
Specific interactions have been highlighted between cyanobacteria and chemotrophic bacteria within the cyanosphere, suggesting that nutrients recycling could be optimized by cyanobacteria/bacteria exchanges. In order to determine the respective metabolic roles of the cyanobacterial and bacterial consortia (microbiome), a day–night metatranscriptomi...
Dziani Dzaha is a maar the age of which is close to 4000 years. While its water is thought to have originated from seawater it is now considered as an extreme environment due to its hypersaline and alkaline characteristics. Those extreme features have led to the simplification of the trophic network. Cyanobacteria account for up to 95% of the photo...
Background: The Balaruc-les-Bains’ thermal mud was found to be colonized predominantly by microorganisms, with cyanobacteria constituting the primary organism in the microbial biofilm observed on the mud surface. The success of cyanobacteria in colonizing this specific ecological niche can be explained in part by their taxa-specific adaptation capa...
Cyanobacteria are able to synthesize a high diversity of natural compounds that account for their success in the colonization of a variety of ecological niches. Many of them have beneficial properties. The mud from the thermal baths of Balaruc-Les-Bains, one of the oldest thermal baths in France, has long been recognized as a healing treatment for...
Microcystis aeruginosa is one of the major species that cause toxic cyanobacterial blooms in freshwater systems worldwide. Here, we report the draft genome sequence of M. aeruginosa PMC 728.11, a microcystin-producing cyanobacterium isolated from the freshwater reservoir of Juanon in Valence, France. The genome sequence contains 276 contigs, consis...
Background: The Balaruc-les-Bains’ thermal mud was found to be colonized predominantly by microorganisms, with cyanobacteria constituting the primary organism in the microbial biofilm observed on the mud surface. The success of cyanobacteria in colonizing this specific ecological niche can be explained in part by their taxa-specific adaptation capa...
Microcystis aeruginosa is one of the major species that causes toxic cyanobacterial blooms in freshwater systems worldwide. Here, we report the draft genome sequence of M. aeruginosa PMC 728.11, a microcystin-producing cyanobacteria isolated from the freshwater reservoir of Juanon in Valence, France. The genome sequence contains 276 contigs, consis...
Abstract The Proterozoic Era records two periods of abundant positive carbon isotope excursions (CIEs), conventionally interpreted as resulting from increased organic carbon burial and leading to Earth’s surface oxygenation. As strong spatial variations in the amplitude and duration of these excursions are uncovered, this interpretation is challeng...
Africa is experiencing high annual population growth in its major river basins. This growth has resulted in significant land use change and pollution pressures on the freshwater ecosystems. Among them, the Lake Victoria basin, with more than 42 million people, is a unique and vital resource that provides food and drinking water in East Africa. Howe...
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...
Efficient RNA extraction methods are needed to study transcript regulation. Such methods must lyse the cell without degrading the genetic material. For cyanobacteria this can be particularly challenging because of the presence of the cyanobacteria cell envelope. The great breath of cyanobacterial shape and size (unicellular, colonial, or filamentou...
Cyanobacteria are an ancient lineage of slow-growing photosynthetic bacteria and a prolific source of natural products with diverse chemical structures and potent biological activities and toxicities. The chemical identification of these compounds remains a major bottleneck. Strategies that can prioritize the most prolific strains and novel compoun...