Search results for "Bacterial"
showing 10 items of 3246 documents
Combining ecophysiological and microbial ecological approaches to assess interaction between genotypes of Medicago truncatula and the soil bacterial …
2011
International audience; Microbial communities can play a key role in sustainable agriculture by improving crop growth. Currently, a major stake is to study the effect of the plant genotype on the shaping of the soil microbial communities in relation to the plant nutrition. Methods: The links between the plant genotype and the rhizospheric bacterial communities were assessed at both structural and functional level using a multidisciplinary approach. On the one side, the genetic structure (Automated Ribosomial Intergenic Spacer Analysis (ARISA)) and diversity (454 pyrosequencing) of bacterial communities of the rhizosphere was first analysed. On the other side, using an ecophysiological model…
Relationships between Staphylococcus aureus genetic background, virulence factors, agr groups (alleles), and human disease
2002
ABSTRACT The expression of most Staphylococcus aureus virulence factors is controlled by the agr locus, which encodes a two-component signaling pathway whose activating ligand is an agr -encoded autoinducing peptide (AIP). A polymorphism in the amino acid sequence of the AIP and of its corresponding receptor divides S. aureus strains into four major groups. Within a given group, each strain produces a peptide that can activate the agr response in the other member strains, whereas the AIPs belonging to different groups are usually mutually inhibitory. We investigated a possible relationship between agr groups and human S. aureus disease by studying 198 S. aureus strains isolated from 14 asym…
Loss in microbial diversity affects nitrogen cycling in soil
2013
International audience; Microbial communities have a central role in ecosystem processes by driving the Earth's biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 s…
Strategies for analyzing interactions between arbuscular mycorrhiza and bacteria
2013
National audience
Inactivation of PadR, the repressor of the phenolic acid stress response, by molecular interaction with Usp1, a universal stress protein from Lactoba…
2009
ABSTRACT The phenolic acid decarboxylase gene padA is involved in the phenolic acid stress response (PASR) in gram-positive bacteria. In Lactobacillus plantarum , the padR gene encodes the negative transcriptional regulator of padA and is cotranscribed with a downstream gene, usp1 , which encodes a putative universal stress protein (USP), Usp1, of unknown function. The usp1 gene is overexpressed during the PASR. However, the role and the mechanism of action of the USPs are unknown in gram-positive bacteria. Therefore, to gain insights into the role of USPs in the PASR; (i) a usp1 deletion mutant was constructed; (ii) the two genes padR and usp1 were coexpressed with padA under its own promo…
Biotechnological applications of the sepiolite interactions with bacteria: Bacterial transformation and DNA extraction
2020
International audience; Among the various clay minerals, sepiolite, which is a natural nanofibrous silicate that exhibit a poor cell toxicity, is a potential promising nanocarrier for the non-viral and stable transfer of plasmid DNA into bacteria, mammalian and human cells. We first show here that sepiolite binds to bacteria, which can be useful in decontamination protocols. In a previous research we have shown that is possible to modulate the efficiency of the absorption of different types of DNA molecules onto sepiolite, and that the DNA previously adsorbed could be recovered preserving the DNA structure and biological activity. Taking advantage of both, the sepiolite/bacteria and sepioli…
Current and New Insights on Molecular Methods to Identify Microbial Growth in Fruit Juices
2018
International audience; Identification of microorganisms in fruit juices plays an important role as it determines the viability of this food product from a commercial point of view. Several microorganisms use fruit as a substrate, thus causing spoilage and generating off‐flavors and odors. In addition, under favorable conditions, toxigenic fungi can produce mycotoxins in fruit juices. Conventional detection and enumeration of microorganisms using traditional plating assays are accurate and can detect low microbial contamination levels. However, in most cases they require long detection times. In recent years, the food industry has shown increased interest in developing new methods with incr…
A new method for the direct quantification of lipopolysaccharide by High Performance Liquid Chromatography coupled with Mass Spectrometry in non-infe…
2017
IF 13.246; International audience
Acute Postcataract Surgery Endophthalmitis Due to Streptococcus Species Differs From Endophthalmitis Due to Staphylococcus Species at Presentation
2009
Purpose: : To correlate the presenting clinical ophthalmic features with the bacterial identification in 100 patients with acute post catarcat endophthalmitis enrolled in the FRench Instutionnal ENdophthalmitis Study (FRIENDS).Methods: : Demographic data, past medical history and initial eye examination were recorded in a standardized form in 100 patients with acute endophthalmitis after cataract extraction (< 6 weeks) in a prospective multicenter study. Relationship between microbiological identification (using conventional cultures and panbacterial PCR) and clinical factors at baseline was studied using univariate (ANOVA).Results: : 100 patients were hospitalized for endophthalmitis treat…
Biogeographical patterns of soil bacterial communities.
2009
International audience; This study provides the first maps of variations in bacterial community structure on a broad scale based on genotyping of DNA extracts from 593 soils from four different regions of France (North, Brittany, South-East and Landes). Soils were obtained from the soil library of RMQS (Réseau de Mesures de la Qualité des Sols = French soil quality monitoring network). The relevance of a biogeographic approach for studying bacterial communities was demonstrated by the great variability in community structure and specific geographical patterns within and between the four regions. The data indicated that the distribution of bacterial community composition might be more relate…