31 research outputs found
Ătude de la diversitĂ© du domaine Bacteria et du rĂšgne Fungi au cours du rouissage du lin sur champ par une approche de metabarcoding
Flax (Linum ustitatissimum L.) dew-retting is a short-term, semi-controlled natural process during which plant cell walls are partially degraded by microorganisms to facilitate fiber extraction for various industrial applications. Under- and over-retting are associated with âbad fiber qualityâ and it is therefore essential to master this process. The microbiology of dew-retting is poorly characterized mainly because it is currently based on the utilization of cultured approaches and phenotypic identification.The implementation of a metabarcoding approach during three independant flax dew-retting campaigns allowed us to characterize, for the first time, the bacterial and fungal community dynamics at this ecosystem level. The taxonomic assignment of OTUs (Operational Taxonomic Units) led to the identification of new taxa not previously associated with dew-retting in particular a high presence of Bacteroidetes phylum. Multivariate analysis and correlation tests identified a number of factors affecting this process. We have demonstrated : (I) that swathe turning has a significant effect on the microbial structures, (ii) the existence of a "terroir" effect and the fact that bacterial communities are affected by precipitation and (iii) the existence of a year effect and the fact that fungal communities are affected by temperature. Bacterial CAZyme (Carbohydrate-Active-Enzymes) predictions, allowed us to identify different families involved in plant cell wall degradation thereby providing a basis for future studies using a metatranscriptomic approach.Le rouissage du lin cultiveÌ (Linum ustitatissimum L.) sur champ est un proceÌdeÌ naturel, rapide et semi-controÌleÌ durant lequel les parois veÌgeÌtales sont partiellement deÌgradeÌes par les micro-organismes afin de faciliter lâextraction des fibres pour diffeÌrents usages industriels. Le sous- et le sur-rouissage sont associeÌs aÌ une mauvaise qualiteÌ de fibre, il est donc essentiel de maiÌtriser ce processus. La microbiologique du rouissage reste encore mal caracteÌriseÌe en raison dâeÌtudes baseÌes uniquement sur des approches de cultures deÌpendantes et dâidentification pheÌnotypique. La mise en place dâune approche de metabarcoding au cours de trois campagnes, nous a permis de caracteÌriser lâeÌvolution des membres et structures du domaine Bacteria et du reÌgne Fungi, aÌ lâeÌchelle de son eÌcosysteÌme, pour la toute premieÌre fois. Lâassignation taxonomique des OTUs (Operational Taxonomic Units) a permis lâidentification de nouveaux taxa encore non associeÌs au rouissage et notamment le phylum Bacteroidetes, treÌs repreÌsenteÌ. GraÌce aux analyses multivarieÌes et aux tests de correÌlations, nous avons identifieÌ plusieurs facteurs influençant ce processus. Nous avons deÌmontreÌ : (i) que le retournement des andains a un effet significatif sur les structures microbiennes, (ii) de lâexistence dâun effet "terroir" avec des communauteÌs bacteÌriennes affecteÌes par les preÌcipitations et (iii) de lâexistence dâun effet "milleÌsime" avec des variations de structures fongiques expliqueÌes par les tempeÌratures. Les preÌdictions des CAZomes (Carbohydrate-Active-Enzymes) bacteÌriens nous ont permis dâidentifier des familles potentiellement impliqueÌes dans la deÌgradation des parois cellulaires qui serviront de base pour une eÌtude plus approfondie par meÌta-transcriptomique
Study of bacterial and fungal diversity during flax dew-retting by using metabarcoding
Le rouissage du lin cultiveÌ (Linum ustitatissimum L.) sur champ est un proceÌdeÌ naturel, rapide et semi-controÌleÌ durant lequel les parois veÌgeÌtales sont partiellement deÌgradeÌes par les micro-organismes afin de faciliter lâextraction des fibres pour diffeÌrents usages industriels. Le sous- et le sur-rouissage sont associeÌs aÌ une mauvaise qualiteÌ de fibre, il est donc essentiel de maiÌtriser ce processus. La microbiologique du rouissage reste encore mal caracteÌriseÌe en raison dâeÌtudes baseÌes uniquement sur des approches de cultures deÌpendantes et dâidentification pheÌnotypique. La mise en place dâune approche de metabarcoding au cours de trois campagnes, nous a permis de caracteÌriser lâeÌvolution des membres et structures du domaine Bacteria et du reÌgne Fungi, aÌ lâeÌchelle de son eÌcosysteÌme, pour la toute premieÌre fois. Lâassignation taxonomique des OTUs (Operational Taxonomic Units) a permis lâidentification de nouveaux taxa encore non associeÌs au rouissage et notamment le phylum Bacteroidetes, treÌs repreÌsenteÌ. GraÌce aux analyses multivarieÌes et aux tests de correÌlations, nous avons identifieÌ plusieurs facteurs influençant ce processus. Nous avons deÌmontreÌ : (i) que le retournement des andains a un effet significatif sur les structures microbiennes, (ii) de lâexistence dâun effet "terroir" avec des communauteÌs bacteÌriennes affecteÌes par les preÌcipitations et (iii) de lâexistence dâun effet "milleÌsime" avec des variations de structures fongiques expliqueÌes par les tempeÌratures. Les preÌdictions des CAZomes (Carbohydrate-Active-Enzymes) bacteÌriens nous ont permis dâidentifier des familles potentiellement impliqueÌes dans la deÌgradation des parois cellulaires qui serviront de base pour une eÌtude plus approfondie par meÌta-transcriptomique.Flax (Linum ustitatissimum L.) dew-retting is a short-term, semi-controlled natural process during which plant cell walls are partially degraded by microorganisms to facilitate fiber extraction for various industrial applications. Under- and over-retting are associated with âbad fiber qualityâ and it is therefore essential to master this process. The microbiology of dew-retting is poorly characterized mainly because it is currently based on the utilization of cultured approaches and phenotypic identification.The implementation of a metabarcoding approach during three independant flax dew-retting campaigns allowed us to characterize, for the first time, the bacterial and fungal community dynamics at this ecosystem level. The taxonomic assignment of OTUs (Operational Taxonomic Units) led to the identification of new taxa not previously associated with dew-retting in particular a high presence of Bacteroidetes phylum. Multivariate analysis and correlation tests identified a number of factors affecting this process. We have demonstrated : (I) that swathe turning has a significant effect on the microbial structures, (ii) the existence of a "terroir" effect and the fact that bacterial communities are affected by precipitation and (iii) the existence of a year effect and the fact that fungal communities are affected by temperature. Bacterial CAZyme (Carbohydrate-Active-Enzymes) predictions, allowed us to identify different families involved in plant cell wall degradation thereby providing a basis for future studies using a metatranscriptomic approach
Nouvelles techniques de méta-omiques pour le diagnostic de la qualité microbiologique des sols
National audienceLes nouvelles techniques de mĂ©ta-omiques ont bouleversĂ© le domaine de lâĂ©cologie microbienne, notamment grĂące Ă lâapport des nouvelles techniques de sĂ©quençage Ă haut dĂ©bit. Cette rĂ©volution a aussi Ă©tĂ© bĂ©nĂ©fique en proposant des outils afin de mesurer et de rĂ©aliser des diagnostics de la qualitĂ© microbiologique des sols. Quels sont les bio-indicateurs utilisĂ©s ? Comment sont-ils Ă©tudiĂ©s et appliquĂ©s Ă grande Ă©chelle ? Dans cet article, seront prĂ©sentĂ©es les diffĂ©rentes techniques de mĂ©ta-omiques illustrĂ©es par des exemples validĂ©s ou en cours de validation ainsi que les dĂ©veloppements futurs afin de rĂ©pondre Ă lâenjeu essentiel dâune meilleure comprĂ©hension et prĂ©servation des sols.Abstact: New meta-omics techniques for diagnosis of soil microbial quality.The new meta-omics techniques have upset the field of microbial ecology, particularly due to the contribution of the new high-throughput sequencing technologies. This revolution has benefited from fundamental research point of view but also by giving access to tools dedicated to new measurements and to carry out soil microbial quality diagnosis. What are the bio-indicators used? How are they studied and applied on a large scale? This article will be focused on the different meta-omic techniques illustrated by valid or undergoing validation examples, as well as future developments in order to answer the essential challenge of a better understanding and preservation of the soil
Characterization of Bacterial and Fungal Community Dynamics by High-Throughput Sequencing (HTS) Metabarcoding during Flax Dew-Retting
Flax dew-retting is a key step in the industrial extraction of fibers from flax stems and is dependent upon the production of a battery of hydrolytic enzymes produced by micro-organisms during this process. To explore the diversity and dynamics of bacterial and fungal communities involved in this process we applied a high-throughput sequencing (HTS) DNA metabarcoding approach (16S rRNA/ITS region, Illumina Miseq) on plant and soil samples obtained over a period of 7 weeks in July and August 2014. Twenty-three bacterial and six fungal phyla were identified in soil samples and 11 bacterial and four fungal phyla in plant samples. Dominant phyla were Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes (bacteria) and Ascomycota, Basidiomycota, and Zygomycota (fungi) all of which have been previously associated with flax dew-retting except for Bacteroidetes and Basidiomycota that were identified for the first time. Rare phyla also identified for the first time in this process included Acidobacteria, CKC4, Chlorobi, Fibrobacteres, Gemmatimonadetes, Nitrospirae and TM6 (bacteria), and Chytridiomycota (fungi). No differences in microbial communities and colonization dynamics were observed between early and standard flax harvests. In contrast, the common agricultural practice of swath turning affects both bacterial and fungal community membership and structure in straw samples and may contribute to a more uniform retting. Prediction of community function using PICRUSt indicated the presence of a large collection of potential bacterial enzymes capable of hydrolyzing backbones and side-chains of cell wall polysaccharides. Assignment of functional guild (functional group) using FUNGuild software highlighted a change from parasitic to saprophytic trophic modes in fungi during retting. This work provides the first exhaustive description of the microbial communities involved in flax dew-retting and will provide a valuable benchmark in future studies aiming to evaluate the effects of other parameters (e.g., year-to year and site variability etc.) on this complex process
Explorer les fonctions microbiennes à partir d'informations taxonomiques : un état de l'art des outils et des méthodes
National audienceĂ l'Ăšre des Big Data, dâĂ©normes quantitĂ©s de donnĂ©es sont disponibles et constituent uneoccasion unique de dĂ©velopper des algorithmes de prĂ©diction performants. En Ă©cologiemicrobienne, ce phĂ©nomĂšne a jouĂ© un rĂŽle majeur dans la façon dont nous abordons labiodiversitĂ© depuis lâapparition des NGS. LâĂ©tude des microbiomes environnementaux par lesoutils les mĂ©ta-omiques a conduit Ă la dĂ©couverte de nouveaux organismes, fournissant ainsiune source importante dâinformations taxonomiques et fonctionnelles. Lâun des futurs dĂ©fis, estde rĂ©ussir Ă associer une fonction Ă une diversitĂ© microbienne pour amĂ©liorer notrecomprĂ©hension des fonctions du microbiome (British Ecological Society, 2016). Bien quecertaines technologies renseignent sur les fonctions putatives ou rĂ©elles, elles restentfastidieuses et coĂ»teuses Ă mettre en oeuvre. Lâapproche de metabarcoding est courammentutilisĂ©e pour obtenir des informations sur la diversitĂ© microbienne avec un coĂ»t trĂšs abordable,mais elle ne permet pas directement dâobtenir des informations sur les fonctions microbiennes.Deux solutions vivement dĂ©battues au sein de la communautĂ© scientifique Ă©mergentactuellement pour tirer des informations fonctionnelles Ă partir d'un profil taxonomique : (i)l'infĂ©rence fonctionnelle et (ii) l'assignation de traits Ă©cologiques. Si la plupart des outilsdisponibles sont utilisables uniquement pour les procaryotes, comme PICRUSt le plus connu,dâautres alternatives existent afin dâĂ©tudier les eucaryotes et notamment les champignonscomme par exemple FUNGuild. Ainsi, nous prĂ©senterons un Ă©tat de lâart des outils et mĂ©thodesdisponibles, illustrĂ©s par diffĂ©rents exemples permettant de faire le lien entre la diversitĂ© descommunautĂ©s et leurs fonctions ou traits Ă©cologiques en ciblant lâenvironnement sol
Dynamic of bacterial and archaeal diversity in a tropical soil over 6 years of repeated organic and inorganic fertilization
International audienceThe soil microbial community plays important roles in nutrient cycling, plant pathogen suppression, decomposition of residues and degradation of pollutants; as such, it is often regarded as a good indicator of soil quality. Repeated applications of mixed organic and inorganic materials in agriculture improve the soil microbial quality and in turn crop productivity. The soil microbial quality following several years of repeated fertilizer inputs has received considerable attention, but the dynamic of this community over time has never been assessed. We used high-throughput sequencing targeting 16S ribosomal RNA genes to investigate the evolution of the bacterial and archaeal community throughout 6 years of repeated organic and inorganic fertilizer applications. Soils were sampled from a field experiment in La Mare (Reunion Island, France), where different mixed organic-inorganic fertilizer inputs characterized by more or less stable organic matter were applied regularly for 6 years. Soil samples were taken each year, more than 6 months after the latest fertilizer application. The soil molecular biomass significantly increased in some organically fertilized plots (by 35â45% on average), 3â5 years after the first fertilizers application. The significant variations in soil molecular microbial biomass were explained by the fertilization practices (cumulated organic carbon inputs) and sometimes by the soil parameters (sand and soil carbon contents). The structure of the bacterial and archaeal community was more influenced by time than by the fertilization type. However, repeated fertilizer applications over time tended to modify the abundance of the bacterial phyla Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes , and Proteobacteria. To conclude, the present study highlights that the soil bacterial and archaeal community is lastingly modified after 6 years of repeated fertilizer inputs. These changes depend on the nature of the organic input and on the fertilization practice (frequency and applied quantity)
Atlas français des champignons du sol
National audienceUn seul gramme de sol peut contenir plusieurs millions de champignons microscopiques !Depuis un milliard dâannĂ©es dâĂ©volution et dâadaptations, le rĂšgne des champignons est un acteur incontournable de la biodiversitĂ© de notre planĂšte. Les champignons sont souvent observĂ©s grĂące Ă leurs sporophores qui se dĂ©veloppent au-dessus du sol. Ces derniers reprĂ©sentent pourtant seulement la pointe de lâiceberg de leur diversitĂ© car les champignons sont en rĂ©alitĂ© majoritairement prĂ©sents sous forme microscopique dans nos sols. Dans cet atlas, les auteurs, qui sont des chercheurs INRAE spĂ©cialistes en Ă©cologie microbienne et en sciences du sol, dĂ©voilent une nouvelle vision des champignons. Ils ont rĂ©alisĂ© le premier inventaire national complet des communautĂ©s de champignons du sol sur lâensemble du territoire national. Ceci a Ă©tĂ© rendu possible grĂące Ă lâutilisation des derniĂšres technologies de sĂ©quençage massif de lâADN environnemental sur les 2 200 sols du RĂ©seau de mesures de la qualitĂ© des sols, couvrant lâensemble de lâhexagone. Cet atlas synthĂ©tise lâensemble des connaissances scientifiques et reprĂ©sente le premier guide naturaliste sur la distribution et lâĂ©cologie des communautĂ©s de champignons du sol Ă lâĂ©chelle de la France, Ă destination du grand public. Il cartographie lâabondance, la diversitĂ© et la composition des communautĂ©s de champignons du sol Ă grande Ă©chelle et permet dâidentifier les paramĂštres de lâenvironnement (e.g., type de sol, climat, mode dâusage, gĂ©omorphologie) qui conditionnent cette distribution.Il aborde aussi plus prĂ©cisĂ©ment la distribution des grands taxa fongiques prĂ©sents dans les sols français, permettant de mieux comprendre leur Ă©cologie en termes de sensibilitĂ© Ă certaines conditions environnementales et dâimplication dans les grandes fonctions et services rendus par les sols. LâAtlas conclut par des dĂ©monstrations opĂ©rationnelles de lâutilisation des champignons en tant que bio-indicateurs de la qualitĂ© des sols pour Ă©valuer lâimpact et la durabilitĂ© de certaines pratiques agricoles, industrielles et urbaines. Un ouvrage unique, tant par le sujet traitĂ© que par des reprĂ©sentations originales permettant dâapprĂ©hender le monde mystĂ©rieux et incroyable de ce rĂšgne invisible des champignons du sol. Lâouvrage est en cours de rĂ©daction, sa parution est prĂ©vue en dĂ©but dâannĂ©e 2024
Inferring microbiota functions from taxonomic genes: a review
International audienceAbstract Deciphering microbiota functions is crucial to predict ecosystem sustainability in response to global change. High-throughput sequencing at the individual or community level has revolutionized our understanding of microbial ecology, leading to the big data era and improving our ability to link microbial diversity with microbial functions. Recent advances in bioinformatics have been key for developing functional prediction tools based on DNA metabarcoding data and using taxonomic gene information. This cheaper approach in every aspect serves as an alternative to shotgun sequencing. Although these tools are increasingly used by ecologists, an objective evaluation of their modularity, portability, and robustness is lacking. Here, we reviewed 100 scientific papers on functional inference and ecological trait assignment to rank the advantages, specificities, and drawbacks of these tools, using a scientific benchmarking. To date, inference tools have been mainly devoted to bacterial functions, and ecological trait assignment tools, to fungal functions. A major limitation is the lack of reference genomesâcompared with the human microbiotaâespecially for complex ecosystems such as soils. Finally, we explore applied research prospects. These tools are promising and already provide relevant information on ecosystem functioning, but standardized indicators and corresponding repositories are still lacking that would enable them to be used for operational diagnosis
SOIL MICROBIOLOGICAL QUALITY: STATE OF THE ART AND IMPORTANCE OF MICROBIAL COMMUNITIES FOR FRENCH AGRICULTURAL SOILS
International audienceSoils are one of the major reservoirs of biological diversity on our planet, hosting a huge diversity of microorganisms. Numerous studies have demonstrated the role of microbial diversity in soil functions, such as nutrient cycling or pathogen management. Given the key role of soil microorganisms in the regulation of soil ecosystem functions, the environmental factors driving soil microbial diversity need to be understood. In France, we have the opportunity to benefit from a national soil survey (called the French Soil Quality Monitoring Network), which represents one of the most extensive and without a priori soil sampling survey available to date. Through several funded projects, we were able to decipher the spatial distribution of microbial diversity at the scale of France. These analyses provided extensive maps of microbial diversity, structure and composition and reveals the heterogeneous and spatially structured distribution of microbial communities at the nationwide scale. We also identified the ecological processes involved in the biogeographical patterns of microbial diversity, and develop co-occurring networks identified within the relative abundance of bacterial taxa dataset to the scale of France in order to better understand the processes involved in community assembly. From an operational point of view, innovative diagnosis tools were developed with obtained datasets, using statistical predictive models according to environmental parameters. They provide reference values fitted for a given pedoclimatic condition, which is to be compared to the corresponding measured data for a robust diagnosis of soil biological quality. These innovative tools allow a robust diagnosis of soil biological quality
AmĂ©liorer la valorisation des effluents dâĂ©levage porcin dans un environnement herbager Ă forte biodiversitĂ©
Webinaire de conclusion du projet Aporthe du 04 mars 2021Le webinaire de conclusion du programme APORTHE sâest dĂ©roulĂ© le jeudi 4 mars en matinĂ©e : « Porcs et bovins dans le Massif central : des complĂ©mentaritĂ©s Ă cultiver« . Il a rassemblĂ© prĂšs de 130 personnes et a permis de dresser un panorama des principaux acquis du programme et des conclusions essentielles qui en ressortent.Impact des pratiques de gestion des effluents dâĂ©levage sur la qualitĂ© microbiologique des sols (Sophie Bourgeteau)Gestion des effluents dans les exploitations mixtes « Porcin â Bovin » (Sylvie Mugnier