Interspecific interactions play an important role in the establishment of a community phenotype. Furthermore, the evolution of a community can both occur through an independent evolution of the species composing the community and the interactions among them. In this study, we investigated how important the evolution of interspecific interactions was in the evolutionary response of eight two-bacterial species communities regarding productivity.
View Article and Find Full Text PDF() is a ubiquitous bacterium that causes the serious foodborne illness listeriosis. Although soil is a primary reservoir and a central habitat for , little information is available on the genetic features underlying the fitness of strains in this complex habitat. The aim of this study was to identify (i) correlations between the strains fitness in soil, their origin and their phylogenetic position (ii) identify genetic markers allowing to survive in the soil.
View Article and Find Full Text PDFThe alternative sigma factor B (σ) contributes to the stress tolerance of the foodborne pathogen Listeria monocytogenes by upregulating the general stress response. We previously showed that σ loss-of-function mutations arise frequently in strains of L. monocytogenes and suggested that mild stresses might favor the selection of such mutations.
View Article and Find Full Text PDFListeria monocytogenes is a human pathogen. It is the causative agent of listeriosis, the leading cause of bacterial-linked foodborne mortality in Europe and elsewhere. Outbreaks of listeriosis have been associated with the consumption of fresh produce including vegetables and fruits.
View Article and Find Full Text PDFThe rhizosphere is a dynamic and complex interface between plant roots and microorganisms. Owing to exudates, a web of interactions establishes among the microbial members of this micro-environment. The present study explored the impact of a bacterial consortium (Azotobacter chroococcum, Bacillus megaterium and Pseudomonas fluorescens, ABP), on the fate of a human pathogen, Listeria monocytogenes EGD-e, in soil and in the rhizospheres of Cajanus cajan and Festuca arundinacea, in addition to its plant growth promoting effect.
View Article and Find Full Text PDFListeria monocytogenes is a food-borne pathogen responsible for the disease listeriosis. It is ubiquitously found in the environment and soil is one of its natural habitats. Listeria monocytogenes is highly capable of coping with various stressful conditions.
View Article and Find Full Text PDFMicrobial communities are continuously exposed to the arrival of alien species. In complex environments such as soil, the success of invasion depends on the characteristics of the habitat, especially the diversity and structure of the residing bacterial communities. While most data available on microbial invasion relies on experiments run under constant conditions, the fate of invading species when the habitat faces disturbances has not yet been addressed.
View Article and Find Full Text PDFDue to rhizodeposits and various microbial interactions, the rhizosphere is an extremely dynamic system, which provides a conductive niche not only for bacteria beneficial to plants but also for those that might pose a potential threat to humans. The importance of bioinoculants as biocontrol agents to combat phytopathogens has been widely recognized. However, little information exists with respect to their role in inhibiting human pathogens in the rhizosphere.
View Article and Find Full Text PDFLittle is known about the regulatory mechanisms that ensure the survival of the food-borne bacterial pathogen Listeria monocytogenes in the telluric environment and on roots. Earlier studies have suggested a regulatory overlap between the Agr cell-cell communication system and the general stress response regulator σB. Here, we investigated the contribution of these two systems to root colonisation and survival in sterilised and biotic soil.
View Article and Find Full Text PDFAs for many opportunistic pathogens, the virulence potential of is highly heterogeneous between isolates and correlated, to some extent, with phylogeny and gene repertoires. In sharp contrast with copious data on intraspecies genome diversity, little is known about transcriptome diversity despite the role of complex genetic regulation in pathogenicity. The current study implemented RNA sequencing to characterize the transcriptome profiles of 33 isolates under optimal growth conditions.
View Article and Find Full Text PDFAppl Environ Microbiol
August 2015
In a recent paper, we demonstrated that inactivation of the Agr system affects the patterns of survival of Listeria monocytogenes (A.-L. Vivant, D.
View Article and Find Full Text PDFFront Cell Infect Microbiol
January 2015
In this study, we investigated whether the Agr communication system of the pathogenic bacterium Listeria monocytogenes was involved in adaptation and competitiveness in soil. Alteration of the ability to communicate, either by deletion of the gene coding the response regulator AgrA (response-negative mutant) or the signal pro-peptide AgrD (signal-negative mutant), did not affect population dynamics in soil that had been sterilized but survival was altered in biotic soil suggesting that the Agr system of L. monocytogenes was involved to face the complex soil biotic environment.
View Article and Find Full Text PDFListeria monocytogenes is the causative agent of the food-borne life threatening disease listeriosis. This pathogenic bacterium received much attention in the endeavor of deciphering the cellular mechanisms that underlie the onset of infection and its ability to adapt to the food processing environment. Although information is available on the presence of L.
View Article and Find Full Text PDFUnderstanding 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.
View Article and Find Full Text PDFListeria monocytogenes is a ubiquitous, opportunistic pathogenic organism. Environmental adaptation requires constant regulation of gene expression. Among transcriptional regulators, AgrA is part of an auto-induction system.
View Article and Find Full Text PDFListeria monocytogenes is a ubiquitous opportunistic pathogen responsible for listeriosis. In order to study the processes underlying its ability to adapt to the soil environment, whole-genome arrays were used to analyse transcriptome modifications 15 minutes, 30 minutes and 18 h after inoculation of L. monocytogenes EGD-e in soil extracts.
View Article and Find Full Text PDFTo investigate if the primary function of the Agr system of Listeria monocytogenes is to monitor cell density, we followed Agr expression in batch cultures, in which the autoinducer concentration was uniform, and in biofilms. Expression was heterogeneous, suggesting that the primary function of Agr is not to monitor population density.
View Article and Find Full Text PDFIn order to withstand changes in their environment, bacteria have evolved mechanisms to sense the surrounding environment, integrate these signals and adapt their physiology to thrive under fluctuating conditions. Among these mechanisms, the ability of bacteria to exchange information between cells has become a dynamic field of interest for microbiologists over the past four decades. First described by Nelson et al.
View Article and Find Full Text PDFThe contribution of growth history and flagella to adhesion of Listeria monocytogenes was analysed. An in-frame deletion on the flagellin encoding gene (flaA) was performed in L. monocytogenes EGD-e to compare its adhesion ability with the parental strain, after cultivation at various pH values and temperatures.
View Article and Find Full Text PDFListeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L.
View Article and Find Full Text PDFBased on bioinformatic data on model fungi, the rodA and wetA genes encoding, respectively, a RodA hydrophobin protein and the WetA protein involved in conidiation mechanisms, were PCR-cloned and characterized for the first time in Penicillium camemberti. These results, completed by a sequence of the brlA gene (available in GenBank), which encodes a major transcriptional regulator also involved in the conidiation mechanism, were used to compare, by qRT-PCR, the expression of the three genes in liquid and solid cultures in a synthetic medium. While expression of the brlA and wetA genes increased dramatically in both culture conditions after 4 days of growth, expression of the rodA gene increased only with conidiation and in the solid culture, and this expression was correlated with production and secretion of a RodA protein outside the hyphae, which became very hydrophobic.
View Article and Find Full Text PDFIn this study, we investigated the agrBDCA operon in the pathogenic bacterium Listeria monocytogenes EGD-e. In-frame deletion of agrA and agrD resulted in an altered adherence and biofilm formation on abiotic surfaces, suggesting the involvement of the agr system of L. monocytogenes during the early stages of biofilm formation.
View Article and Find Full Text PDFIn this study we analyzed under various pH conditions including low pH, the effects of L-malic acid and citric acid, combined or not, on the growth, the proton motive force components and the transcription level of selected genes of the heterolactic bacterium Oenococcus oeni. It is shown here that L-malate enhanced the growth yield at pH equal or below 4.5 while the presence of citrate in media led to a complete and unexpected inhibition of the growth at pH 3.
View Article and Find Full Text PDFLuxS is responsible for the production of autoinducer 2 (AI-2), which is involved in the quorum-sensing response of Vibrio harveyi. AI-2 is found in several other gram-negative and gram-positive bacteria and is therefore considered a good candidate for an interspecies communication signal molecule. In order to determine if this system is functional in the gastrointestinal pathogen Listeria monocytogenes EGD-e, an AI-2 bioassay was performed with culture supernatants.
View Article and Find Full Text PDFAllelic exchange of the region coding for the C terminus of InlA between one epidemic (with an 80-kDa InlA) and one asymptomatic (with a 47-kDa InlA) carriage Listeria monocytogenes strain confirmed the need for this region for internalin entry in vitro. Interestingly, restoration of internalin A functionality did not result in full virulence in chicken embryo assays.
View Article and Find Full Text PDF