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Author: Denis Le Paslier (33)


Mar
2017

Metagenomics has made accessible an enormous reserve of global biochemical diversity. To tap into this vast resource of novel enzymes, we have screened over one million clones from metagenome DNA libraries derived from sixteen different environments for carboxylesterase activity and identified 714 positive hits. We have validated the esterase activity of 80 selected genes, which belong to 17 different protein families including unknown and cyclase-like proteins.

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Dec
1969

Chlordecone (Kepone®) is a synthetic organochlorine insecticide (C10Cl10O) used worldwide mostly during the 1970 and 1980s. Its intensive application in the French West Indies to control the banana black weevil Cosmopolites sordidus led to a massive environmental pollution. Persistence of chlordecone in soils and water for numerous decades even centuries causes global public health and socio-economic concerns.

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Dec
1969

Despite extensive direct sequencing efforts and advanced analytical tools, reconstructing microbial genomes from soil using metagenomics have been challenging due to the tremendous diversity and relatively uniform distribution of genomes found in this system. Here we used enrichment techniques in an attempt to decrease the complexity of a soil microbiome prior to sequencing by submitting it to a range of physical and chemical stresses in 23 separate microcosms for 4 months. The metagenomic analysis of these microcosms at the end of the treatment yielded 540 Mb of assembly using standard de novo assembly techniques (a total of 559,555 genes and 29,176 functions), from which we could recover novel bacterial genomes, plasmids and phages.

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Jul
2015

To gain an in-depth insight into the diversity and the distribution of genes under the particular evolutionary pressure of an arsenic-rich acid mine drainage (AMD), the genes involved in bacterial arsenic detoxification (arsB, ACR3) and arsenite oxidation (aioA) were investigated in sediment from Carnoulès (France), in parallel to the diversity and global distribution of the metabolically active bacteria. The metabolically active bacteria were affiliated mainly to AMD specialists, i.e.

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Aug
2014

The bacterial oxidation of nitrite to nitrate is a key process of the biogeochemical nitrogen cycle. Nitrite-oxidizing bacteria are considered a highly specialized functional group, which depends on the supply of nitrite from other microorganisms and whose distribution strictly correlates with nitrification in the environment and in wastewater treatment plants. On the basis of genomics, physiological experiments, and single-cell analyses, we show that Nitrospira moscoviensis, which represents a widely distributed lineage of nitrite-oxidizing bacteria, has the genetic inventory to utilize hydrogen (H2) as an alternative energy source for aerobic respiration and grows on H2 without nitrite.

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Aug
2014

Most current approaches for analyzing metagenomic data rely on comparisons to reference genomes, but the microbial diversity of many environments extends far beyond what is covered by reference databases. De novo segregation of complex metagenomic data into specific biological entities, such as particular bacterial strains or viruses, remains a largely unsolved problem. Here we present a method, based on binning co-abundant genes across a series of metagenomic samples, that enables comprehensive discovery of new microbial organisms, viruses and co-inherited genetic entities and aids assembly of microbial genomes without the need for reference sequences.

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Dec
1969

The discovery of ammonia-oxidizing archaea (AOA) of the phylum Thaumarchaeota and the high abundance of archaeal ammonia monooxygenase subunit A encoding gene sequences in many environments have extended our perception of nitrifying microbial communities. Moreover, AOA are the only aerobic ammonia oxidizers known to be active in geothermal environments. Molecular data indicate that in many globally distributed terrestrial high-temperature habits a thaumarchaeotal lineage within the Nitrosopumilus cluster (also called "marine" group I.

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Apr
2013

Next-generation sequencing (NGS) allows faster acquisition of metagenomic data, but complete exploration of complex ecosystems is hindered by the extraordinary diversity of microorganisms. To reduce the environmental complexity, we created an innovative solution hybrid selection (SHS) method that is combined with NGS to characterize large DNA fragments harbouring biomarkers of interest. The quality of enrichment was evaluated after fragments containing the methyl coenzyme M reductase subunit A gene (mcrA), the biomarker of methanogenesis, were captured from a Methanosarcina strain and a metagenomic sample from a meromictic lake.

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Oct
2012

In this study, archaeal community structure and temporal dynamics were monitored, using 16S rRNA clone libraries construction from a horizontal subsurface flow constructed wetland. Phylogenetic assignation of 1026 16S rRNA gene sequences shows that 96.2% of the total operational taxonomic units (OTUs) were affiliated with Thaumarchaeota, a newly proposed archaeal phylum and 3.

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May
2013

Performance of biological wastewater treatment systems may be related to the composition and activity of microbial populations they contain. However, little information is known regarding microbial community inhabiting these ecosystems. The purpose of this study was to investigate archaeal and bacterial diversity, using cultivation-independent molecular techniques, in a constructed wetland receiving domestic wastewater.

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Dec
2012

Nitrite-oxidizing bacteria (NOB) catalyze the second step of nitrification, a major process of the biogeochemical nitrogen cycle, but the recognized diversity of this guild is surprisingly low and only two bacterial phyla contain known NOB. Here, we report on the discovery of a chemolithoautotrophic nitrite oxidizer that belongs to the widespread phylum Chloroflexi not previously known to contain any nitrifying organism. This organism, named Nitrolancetus hollandicus, was isolated from a nitrifying reactor.

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Sep
2012

The soil ecosystem is critical for human health, affecting aspects of the environment from key agricultural and edaphic parameters to critical influence on climate change. Soil has more unknown biodiversity than any other ecosystem. We have applied diverse DNA extraction methods coupled with high throughput pyrosequencing to explore 4.

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Mar
2012

In this study, the PAH-degrading bacteria of a constructed wetland collecting road runoff has been studied through DNA stable isotope probing. Microcosms were spiked with (13)C-phenanthrene at 34 or 337 ppm, and bacterial diversity was monitored over a 14-day period. At 337 ppm, PAH degraders became dominated after 5 days by Betaproteobacteria, including novel Acidovorax, Rhodoferax and Hydrogenophaga members, and unknown bacteria related to Rhodocyclaceae.

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Nov
2011

By their metabolic activities, microorganisms have a crucial role in the biogeochemical cycles of elements. The complete understanding of these processes requires, however, the deciphering of both the structure and the function, including synecologic interactions, of microbial communities. Using a metagenomic approach, we demonstrated here that an acid mine drainage highly contaminated with arsenic is dominated by seven bacterial strains whose genomes were reconstructed.

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May
2011

Enterotypes of the human gut microbiome.

Nature 2011 May 20;473(7346):174-80. Epub 2011 Apr 20.
Manimozhiyan Arumugam, Jeroen Raes, Eric Pelletier, Denis Le Paslier, Takuji Yamada, Daniel R Mende, Gabriel R Fernandes, Julien Tap, Thomas Bruls, Jean-Michel Batto, Marcelo Bertalan, Natalia Borruel, Francesc Casellas, Leyden Fernandez, Laurent Gautier, Torben Hansen, Masahira Hattori, Tetsuya Hayashi, Michiel Kleerebezem, Ken Kurokawa, Marion Leclerc, Florence Levenez, Chaysavanh Manichanh, H Bjørn Nielsen, Trine Nielsen, Nicolas Pons, Julie Poulain, Junjie Qin, Thomas Sicheritz-Ponten, Sebastian Tims, David Torrents, Edgardo Ugarte, Erwin G Zoetendal, Jun Wang, Francisco Guarner, Oluf Pedersen, Willem M de Vos, Søren Brunak, Joel Doré, , María Antolín, François Artiguenave, Hervé M Blottiere, Mathieu Almeida, Christian Brechot, Carlos Cara, Christian Chervaux, Antonella Cultrone, Christine Delorme, Gérard Denariaz, Rozenn Dervyn, Konrad U Foerstner, Carsten Friss, Maarten van de Guchte, Eric Guedon, Florence Haimet, Wolfgang Huber, Johan van Hylckama-Vlieg, Alexandre Jamet, Catherine Juste, Ghalia Kaci, Jan Knol, Omar Lakhdari, Severine Layec, Karine Le Roux, Emmanuelle Maguin, Alexandre Mérieux, Raquel Melo Minardi, Christine M'rini, Jean Muller, Raish Oozeer, Julian Parkhill, Pierre Renault, Maria Rescigno, Nicolas Sanchez, Shinichi Sunagawa, Antonio Torrejon, Keith Turner, Gaetana Vandemeulebrouck, Encarna Varela, Yohanan Winogradsky, Georg Zeller, Jean Weissenbach, S Dusko Ehrlich, Peer Bork
Our knowledge of species and functional composition of the human gut microbiome is rapidly increasing, but it is still based on very few cohorts and little is known about variation across the world. By combining 22 newly sequenced faecal metagenomes of individuals from four countries with previously published data sets, here we identify three robust clusters (referred to as enterotypes hereafter) that are not nation or continent specific. We also confirmed the enterotypes in two published, larger cohorts, indicating that intestinal microbiota variation is generally stratified, not continuous.

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May
2011

Acid mine drainage of the Carnoulès mine (France) is characterized by acid waters containing high concentrations of arsenic and iron. In the first 30 m along the Reigous, a small creek draining the site, more than 38% of the dissolved arsenic was removed by co-precipitation with Fe(III), in agreement with previous studies, which suggest a role of microbial activities in the co-precipitation of As(III) and As(V) with Fe(III) and sulfate. To investigate how this particular ecosystem functions, the bacterial community was characterized in water and sediments by 16S rRNA encoding gene library analysis.

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Oct
2010

Clostridium sticklandii belongs to a cluster of non-pathogenic proteolytic clostridia which utilize amino acids as carbon and energy sources. Isolated by T.C.

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Jul
2010

Nitrospira are barely studied and mostly uncultured nitrite-oxidizing bacteria, which are, according to molecular data, among the most diverse and widespread nitrifiers in natural ecosystems and biological wastewater treatment. Here, environmental genomics was used to reconstruct the complete genome of "Candidatus Nitrospira defluvii" from an activated sludge enrichment culture. On the basis of this first-deciphered Nitrospira genome and of experimental data, we show that Ca.

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Mar
2010

Only three biological pathways are known to produce oxygen: photosynthesis, chlorate respiration and the detoxification of reactive oxygen species. Here we present evidence for a fourth pathway, possibly of considerable geochemical and evolutionary importance. The pathway was discovered after metagenomic sequencing of an enrichment culture that couples anaerobic oxidation of methane with the reduction of nitrite to dinitrogen.

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Aug
2010

A culture-independent molecular phylogenetic approach was used to study prokaryotic diversity in an anoxic activated sludge from a municipal wastewater treatment plant. Two 16S rRNA gene libraries were constructed using total genomic DNA and amplified by polymerase chain reaction using primers specific for archaeal or bacterial domains. Phylogenetic analysis of 132 and 249 almost full-length 16S rRNA genes for Archaea and Bacteria, respectively, was done using the ARB software package.

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May
2009

For the ornithine fermentation pathway, described more than 70 years ago, genetic and biochemical information are still incomplete. We present here the experimental identification of the last four missing genes of this metabolic pathway. They encode L-ornithine racemase, (2R,4S)-2,4-diaminopentanoate dehydrogenase, and the two subunits of 2-amino-4-ketopentanoate thiolase.

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Feb
2009

Sulfur-oxidizing prokaryotes (SOP) catalyse a central step in the global S-cycle and are of major functional importance for a variety of natural and engineered systems, but our knowledge on their actual diversity and environmental distribution patterns is still rather limited. In this study we developed a specific PCR assay for the detection of dsrAB that encode the reversely operating sirohaem dissimilatory sulfite reductase (rDSR) and are present in many but not all published genomes of SOP. The PCR assay was used to screen 42 strains of SOP (most without published genome sequence) representing the recognized diversity of this guild.

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Sep
2008

A novel anaerobic, mesophilic, amino-acid-utilizing bacterium, strain 158T, was isolated from an anaerobic digester of a wastewater treatment plant. Cells of strain 158T were non-motile, rod-shaped (2.0-3.

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Aug
2008

We have constructed a large fosmid library from a mesophilic anaerobic digester and explored its 16S rDNA diversity using a high-density filter DNA-DNA hybridization procedure. We identified a group of 16S rDNA sequences forming a new bacterial lineage named WWE3 (Waste Water of Evry 3). Only one sequence from the public databases shares a sequence identity above 80% with the WWE3 group which hence cannot be affiliated to any known or candidate prokaryotic division.

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Nov
2008

Nitrite-oxidizing bacteria of the genus Nitrospira are ubiquitous in natural ecosystems and also in wastewater treatment plants. Nitrospira are members of a distinct phylum, not closely related to other nitrifiers, and no genomic sequences from this genus have been available so far. Here we applied an environmental genomics approach to sequence and assemble a 137 kbp-long genome fragment of 'Candidatus Nitrospira defluvii', which had been enriched from activated sludge and belongs to Nitrospira sublineage I without isolated representatives.

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Apr
2008

Many microorganisms live in anaerobic environments. Most of these microorganisms have not yet been cultivated. Here, we present, from a metagenomic analysis of an anaerobic digester of a municipal wastewater treatment plant, a reconstruction of the complete genome of a bacterium belonging to the WWE1 candidate division.

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Apr
2006

Anaerobic ammonium oxidation (anammox) has become a main focus in oceanography and wastewater treatment. It is also the nitrogen cycle's major remaining biochemical enigma. Among its features, the occurrence of hydrazine as a free intermediate of catabolism, the biosynthesis of ladderane lipids and the role of cytoplasm differentiation are unique in biology.

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Nov
2005

The chemolithoautotrophic anammox bacterium Candidatus "Kuenenia stuttgartiensis" grows anaerobically using ammonium as electron donor for nitrite reduction. More than 10% of the proteins in cell extracts of "K. stuttgartiensis" consist of c-type heme proteins.

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Aug
2005

A culture-independent molecular phylogenetic approach was used to study prokaryotic diversity in an anaerobic sludge digester. Two 16S rRNA gene libraries were constructed using total genomic DNA, and amplified by polymerase chain reaction (PCR) using primers specific for archaeal or bacterial domains. Phylogenetic analysis of 246 and 579 almost full-length 16S rRNA genes for Archaea and Bacteria, respectively, was performed using the ARB software package.

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Apr
2005

In a previous study, we analyzed the molecular diversity of Planctomycetales by PCR amplification and sequencing of 16S rRNA clone libraries generated from a municipal wastewater plant, using planctomycete-specific and universal primer sets (R. Chouari, D. Le Paslier, P.

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Dec
2003

We examined anoxic and aerobic basins and an anaerobic digestor of a municipal wastewater treatment plant for the presence of novel planctomycete-like diversity. Three 16S rRNA gene libraries were constructed by using a 16S rRNA-targeted universal reverse primer and a forward PCR primer specific for Planctomyces: Phylogenetic analysis of 234 16S rRNA gene sequences defined 110 operational taxonomic units. The majority of these sequences clustered with the four known genera, Pirellula (32%), Planctomyces (18.

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