Search results for "16S"

Phylogenetic comparison of symbiotic (nodC and nifH) and 16S rRNA genes in strains of Rhizobium, Mesorhizobium and Bradyrhizobium isolated from Astra…

2000

Various studies reported different conclusions on the phylogenetic relationship between symbiotic (nod and nif) and chromosomal (16S rRNA) genes in rhizobia (Haukka et al, 1998). Some studies suggested that the phylogeny of nod genes could be related with the host plant (Ueda et al., 1995). In a previous study, rhizobia (44 isolates) from Astragalus, Oxytropis and Onobrychis pp have been classified into 14 distinct 16S rRNA gene types independently of their host plant and geographic origin. The majority of isolates were classified within the genus Mesorhizobium, and few within Rhizobium and Bradyrhizobium genera (Laguerre et al., 1997). The aim of the present study was to determine the dive…

Single-cell RNA sequencing unveils the shared and the distinct cytotoxic hallmarks of human TCRVδ1 and TCRVδ2 γδ T lymphocytes

2019

γδ T lymphocytes represent ∼1% of human peripheral blood mononuclear cells and even more cells in most tissues of vertebrates. Although they have important anticancer functions, most current single-cell RNA sequencing (scRNA-seq) studies do not identify γδ T lymphocytes because their transcriptomes at the single-cell level are unknown. Here we show that high-resolution clustering of large scRNA-seq datasets and a combination of gene signatures allow the specific detection of human γδ T lymphocytes and identification of their T cell receptor (TCR)Vδ1 and TCRVδ2 subsets in large datasets from complex cell mixtures. In t -distributed stochastic neighbor embedding plots from blood and tumor sa…

Microbial diversity and structure are drivers of the biological barrier effect against Listeria monocytogenes in soil

2013

International audience; Understanding the ecology of pathogenic organisms is important in order to monitor their transmission in the environment and the related health hazards. We investigated the relationship between soil microbial diversity and the barrier effect against Listeria monocytogenes invasion. By using a dilution-to-extinction approach, we analysed the consequence of eroding microbial diversity on L. monocytogenes population dynamics under standardised conditions of abiotic parameters and microbial abundance in soil microcosms. We demonstrated that highly diverse soil microbial communities act as a biological barrier against L. monocytogenes invasion and that phylogenetic compos…

Characterization of rhizobia nodulating chickpea in Tunisia

2001

Cent cinquante rhizobia nodulant le pois chiche (Cicer arietinum L.) ont ete isoles a partir de sols echantillonnes dans differentes regions de Tunisie. L'inoculation de la plante hote avec ces isolats montre une variabilite dans le temps d'apparition des premieres nodosites. Cinq isolats induisent des nodosites deux semaines apres inoculation alors que pour les 145 isolats restants les nodosites ne sont observees qu'apres au moins quatre semaines. L'etude par PCR/RFLP de l'ADNr 16S a permis de rattacher les isolats du premier groupe a l'espece Mesorhizobium mediterraneum et ceux du second groupe a l'espece Sinorhizobium medicae. La position taxonomique des isolats a ete confirmee par leurs…

Apport des nouvelles générations de séquençage pour accéder à la diversité des communautés microbiennes du sol : nécessité d’un ‘pipeline’ bio-inform…

2012

National audience

Legacy effects of contrasting water and N-availability patterns on plantmicrobial response to rewetting

2019

National audience; Introduction. Shifts in the frequency and magnitude of rain events (precipitation regime) associated with climate change may affect plant morphological and physiological strategies as well as soil microbial activity.Objectives. The objective of this study was to determine i) how precipitation history shapes the response dynamics of soil bacterial and fungal communities to rewetting, as well as plant-microbial competition for N, and ii) how the N status of the system may modulate the effect of precipitation regime.Materials & methods. The legacy effects of 12 weeks of contrasting precipitation (frequent or infrequent watering, equal total water input) and N inputs was asse…

Recherche d'indicateurs de la résistance des sols aux maladies d'origine tellurique

2014

Different Medicago truncatula genotypes, expressing different phenotypes, modulate microbial functional genes in the rhizosphere

2022

Plants host in their rhizosphere a remarkable diversity of microorganisms that in return promote plant growth and health. Thus, the plant microbiota emerges as a novel component that expand the capacity of plants to adapt to the environment, and thus pave the way for future breeding approaches.It is widely known that different plant species harbor different microbiota, but very few studies showed an impact of the plant genotypes on the microbiota. These contrasting results may depend on the choice of the tested genotypes.We formulate the hypothesis that only those plant genotypes showing high genetic diversity and expressing different phenotypes harbor different rhizosphere microbiota and a…

Evidence of atrazine mineralization in a soil from the Nile Delta: Isolation of Arthrobacter sp. TES6, an atrazine-degrading strain

2011

International audience; The s-triazine herbicide atrazine was rapidly mineralized (i.e., about 60% of C-14-ring-labelled atrazine released as (CO2)-C-14 within 21 days) by an agricultural soil from the Nile Delta (Egypt) that had been cropped with corn and periodically treated with this herbicide. Seven strains able to degrade atrazine were isolated by enrichment cultures of this soil. DNA fingerprint and phylogenetic studies based on 165 rRNA analysis showed that the seven strains were identical and belonged to the phylogeny of the genus Arthrobacter (99% similarity with Arthrobacter sp. AD38, EU710554). One strain, designated Arthrobacter sp. strain TES6, degraded atrazine and mineralized…

Impact of a new bio-pesticide produced by Paenibacillus sp. strain B2 on the genetic structure and density of soil bacterial communities

2007

The effect of paenimyxin, a new biopesticide produced by Paenibacillus sp. strain B2, on the density of soil bacterial communities was assessed by colony counting and by 16S rDNA and nirK quantitative polymerase chain reaction (PCR). Paenimyxin had a negative effect on the bacterial colony-forming unit (CFU) number, which was significantly reduced 2 and 4 days after treatment. The effect of paenimyxin on cultivatable bacteria was negligible 7 days after treatment. Approximately 107 16S rDNA sequences per gram of soil (dry weight) were detected by quantitative PCR in all samples. Paenimyxin did not affect the quantification of 16S rDNA or of the denitrifying bacterial community. In addition,…