Search results for "microbial communities"

A spatially explicit model to simulate soil microbial communities’ dynamics at an agricultural landscape scale

2021

Soil microorganisms play a major role in soil functions and are an efficient indicator to evaluate the impact of agricultural practices on soil quality. Biogeographical studies over wide scales ranging from landscape to countries have concluded that soil microbial abundance and soil prokaryotic richness is following a heterogeneous distribution in space under the dependence of soil properties (e.g. pH, soil texture, organic matter content) and agricultural practices. The goal of this study is the creation of a model that can predict dynamics of soil microbial communities depending on the agricultural management over time. For this, we focus on a monitored landscape (Fénay landscape, 1.200 h…

A new tool to assess the ecotoxicological impact of β-triketone herbicides on soil microbial communities

2018

International audience; The β-triketone herbicides are post-emergence maize selective herbicides that have beenintroduced on the market, in replacement of atrazine, banned in Europe in 2004. Qualified as “eco-friendly”, since they are based on natural phytotoxin properties, these herbicides target an enzymeinvolved in carotenoid biosynthesis called 4-hydroxyphenylpyruvate dioxygenase (HPPD) encoded bythe hppd gene. The inhibition of this enzyme provokes bleaching symptoms, necrosis and death ofweeds.The hppd gene is not only find in eukaryotes such as plants, animals and humans but also inprokaryotes such as fungi, yeasts and bacteria. In recent studies, we showed that, within the soil bact…

Determinants of the distribution of nitrogen-cycling microbial communities at the landscape-scale

2010

Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. However, a landscape perspective is needed to understand the relative importance of local and regional factors and land management for the microbial communities. In this manuscript, we investigated the distribution of functional microbial communities involved in N-cycling and of the total bacterial and crenarchaeal communities over 107 sites using a grid with a 16 km lag distance within Burgundy, a 31 500 km2 region in France. After quantifying the abundances of the total bacterial, crenarchaeal, nitrate-reducing, denitrifying and ammonia-oxidizing communit…

Prévalence de pathogènes humains dans les sols français, effet des facteurs pédoclimatiques, biologiques et du mode d'utilisation des sols

2013

Soil contamination by bacterial pathogens can occur through manure, sewage sludge spreading or irrigation using waste water treatment plants effluents. Agricultural soils may act as reservoirs for these pathogens, play a significant role in their dissemination, leading to the potential contamination of food and water resources. Health risk associated with the occurrence of pathogens in environmental matrices has to be thoroughly evaluated. In this context, the objectives of this work were: i) to determine the prevalence of two pathogenic bacterial species (Listeria monocytogenes and Enterococcus faecalis) in a large collection of French soils originated from a systematic soil survey of the …

Biogeography of soil microbial communities: a review and a description of the ongoing french national initiative

2010

International audience; Microbial biogeography is the study of the distribution of microbial diversity on large scales of space and time. This science aims at understanding biodiversity regulation and its link with ecosystem biological functioning, goods and services such as maintenance of productivity, of soil and atmospheric quality, and of soil health. Although the initial concept dates from the early 20th century (Beijerinck (1913) De infusies en de ontdekking der backterien, in: Jaarboek van de Knoniklijke Akademie van Wetenschappen, Muller, Amsterdam), only recently have an increasing number of studies have investigated the biogeographical patterns of soil microbial diversity. A such …

DIAGSOL : development of a new functional marker of exposure to herbicides B-triketones in an agricultural soil

2020

Numerous herbicides target an enzyme found not only in weeds but also in « non-target organisms » such as microorganisms. This proof-of-concept study aims to use microbial gene encoding the targeted enzyme or the targeted enzyme itself as a marker for herbicide exposure in soils. The hppd gene and the encoded enzyme (HPPD; 4-hydroxyphenylpyruvate dioxygenase), targeted by B-triketone herbicides, are the subject of this study. In silico analyses reveal that the hppd gene is spread out in all bacterial phyla. Primers specific to this gene were designed. This primer pair is used to measure the abundance, the composition and the diversity of the hppd bacterial community in soil microcosms expos…

Distribution and determinism of abundance, diversity and structure of microbial communities at different spatial scales to support agricultural devel…

2018

Les propriétés des sols déterminent notre capacité à produire des biens et des services en quantité et en qualité. Dans ce contexte, la composante microbienne des sols occupe une place prépondérante de part son abondance et son extrême diversité : on estime qu’un gramme de sol contient 109 bactéries et 105 champignons, pour environ 106 espèces bactériennes et 103 à 104 espèces de champignons. Cette diversité taxonomique des microorganismes du sol supporte une extraordinaire diversité fonctionnelle qui leur confère un rôle déterminant dans le fonctionnement du sol tant qualitativement (cycles biogéochimiques, structure du sol ; dégradation des composés exogènes, régulation biologique) que qu…

Plant genotype: a lever in the interactions between plant and its associated rhizosphere microbiome

2018

International audience; In the context of highly pressured agricultural production using low levels of inputs, cropping strategies could take advantage of existing plant-microbiome interactions that can improve both plant growth and health. We believe that plant genetics can provide some clues to better understand the mechanisms underlying microbiome recruitment by the plant.The aims of this work were (i) to assess plant genotype effect on the rhizosphere bacterial communities in relation to the plant nutritional strategies for a core collection of 155 genotypes of Medicago truncatula and (ii) to highlight the genetic determinisms potentially associated in these interactions. To achieve the…

Spatial distribution of ammonia oxidizing bacteria and archaea across a 44-hectare farm related to ecosystem functioning

2011

Use of functional traits to study microbial diversity

2012

Microbial communities have a central role in many ecosystem functions such as biogeochemical cycling, filtering and climate regulation. However, while functional trait-based approaches are commonly used for at least two decades in microbiology, most microbial ecology studies are still carried out with the rRNA genes. This talk will highlight the advantages of trait-based approaches for studying microbial diversity and its relationship with ecosystem functions. For this purpose, denitrification, a microbial process involved in N-cycling, was selected as a model functional trait. Using both naturally assembled and artificially manipulated communities, we will show how the diversity of the den…