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Bacteria are often exposed to nitrosative stress from their environment, from atmospheric pollution or from the defense mechanisms of other organisms. Reactive nitrogen species (RNS), which mediate nitrosative stress, are notably involved in the mammalian immune response through the production of nitric oxide (NO) by the inducible NO synthase iNOS. RNS are highly reactive and can alter various biomolecules such as lipids, proteins and DNA, making them toxic for biological organisms. Resistance to RNS is therefore important for the survival of bacteria in various environments, and notably to successfully infect their host. The fuel combustion processes used in industries and transports are responsible for the emission of important quantities of two major RNS, NO and the more toxic nitrogen dioxide (NO2). Human exposure to NO2 is notably linked to increases in lung infections. While the response of bacteria to NO in liquid medium is well-studied, few data are available on their exposure to gaseous NO and NO2. This study showed that NO2 is much more toxic than NO at similar concentrations for the airborne bacterial strain Pseudomonas fluorescens MFAF76a. The response to NO2 involves a wide array of effectors, while the response to NO seemingly focuses on the Hmp flavohemoprotein. Results showed that NO2 induces the production of other RNS, unlike NO, which could explain the differences between the effects of these two molecules.

Bacteria are often exposed to nitrosative stress from their environment, from atmospheric pollution or from the defense mechanisms of other organisms. Reactive nitrogen species (RNS), which mediate nitrosative stress, are notably involved in the mammalian immune response through the production of nitric oxide (NO) by the inducible NO synthase iNOS. RNS are highly reactive and can alter various biomolecules such as lipids, proteins and DNA, making them toxic for biological organisms. Resistance to RNS is therefore important for the survival of bacteria in various environments, and notably to successfully infect their host. The fuel combustion processes used in industries and transports are responsible for the emission of important quantities of two major RNS, NO and the more toxic nitrogen dioxide (NO

The geocaulosphere is home to microbes that establish communication between themselves and others that disrupt them. These cell-to-cell communication systems are based on the synthesis and perception of signaling molecules, of which the best known belong to the N-acyl-homoserine lactone (AHL) family. Among indigenous bacteria, certain Gram-positive actinobacteria can sense AHLs produced by soft-rot Gram-negative phytopathogens and can degrade the quorum-sensing AHL signals to impair the expression of virulence factors. We mimicked this interaction by introducing dual-color reporter strains suitable for monitoring both the location of the cells and their quorum-sensing and -quenching activities, in potato tubers. The exchange of AHL signals within the pathogen’s cell quorum was clearly detected by the presence of bright green fluorescence instead of blue in a portion of Pectobacterium-tagged cells. This phenomenon in Rhodococcus cells was accompanied by a change from red fluorescence to orange, showing that the disappearance of signaling molecules is due to rhodococcal AHL degradation rather than the inhibition of AHL production. Rhodococci are victorious in this fight for the control of AHL-based communication, as their jamming activity is powerful enough to prevent the onset of disease symptoms.

Legionella pneumophila, the causative agent of Legionnaires’ disease, is mostly found in man-made water systems and is one of the most closely monitored waterborne pathogens. With the aim of finding natural ways to control waterborne pathogens and thus further reduce the impact of disinfection by-products on human health, some studies have demonstrated the ability of bacteria to kill Legionella through the production of secondary metabolites or antimicrobial compounds. Here, we describe an unexpected growth inhibition of L. pneumophila when exposed to a physically separated strain of Pseudomonas fluorescens, designated as MFE01. Most of the members of the Legionellaceae family are sensitive to the volatile substances emitted by MFE01, unlike other bacteria tested. Using headspace solid-phase microextraction GC-MS strategy, a volatilome comparison revealed that emission of 1-undecene, 2-undecanone, and 2-tridecanone were mainly reduced in a Tn5-transposon mutant unable to inhibit at distance the growth of L. pneumophila strain Lens. We showed that 1-undecene was mainly responsible for the inhibition at distance in vitro, and led to cell lysis in small amounts, as determined by gas chromatography-mass spectrometry (GC-MS). Collectively, our results provide new insights into the mode of action of bacterial volatiles and highlight them as potent anti-Legionella agents to focus research on novel strategies to fight legionellosis. IMPORTANCE Microbial volatile compounds are molecules whose activities are increasingly attracting the attention of researchers. Indeed, they can act as key compounds in long-distance intrakingdom and interkingdom communication, but also as antimicrobials in competition and predation. In fact, most studies to date have focused on their antifungal activities and only a few have reported on their antibacterial properties. Here, we describe that 1-undecene, naturally produced by P. fluorescens, is a volatile with potent activity against bacteria of the genus Legionella. In small amounts, it is capable of inducing cell lysis even when the producing strain is physically separated from the target. This is the first time that such activity is described. This molecule could therefore constitute an efficient compound to counter bacterial pathogens whose treatment may fail, particularly in pulmonary diseases. Indeed, inhalation of these volatiles should be considered as a possible route of therapy in addition to antibiotic treatment.

Type VI secretion systems (T6SSs) are contractile bacterial multiprotein nanomachines that enable the injection of toxic effectors into prey cells. The Pseudomonas fluorescens MFE01 strain has T6SS antibacterial activity and can immobilise competitive bacteria through the T6SS. Hcp1 (hemolysin co-regulated protein 1), a constituent of the T6SS inner tube, is involved in such prey cell inhibition of motility. Paradoxically, disruption of the hcp1 or T6SS contractile tail tssC genes results in the loss of the mucoid and motile phenotypes in MFE01. Here, we focused on the relationship between T6SS and flagella-associated motility. Electron microscopy revealed the absence of flagellar filaments for MFE01&Delta, hcp1 and MFE01&Delta, tssC mutants. Transcriptomic analysis showed a reduction in the transcription of class IV flagellar genes in these T6SS mutants. However, transcription of fliA, the gene encoding the class IV flagellar sigma factor, was unaffected. Over-expression of fliA restored the motile and mucoid phenotypes in both MFE01&Delta, hcp1+fliA, and MFE01&Delta, tssC+fliA and a fliA mutant displayed the same phenotypes as MFE01&Delta, tssC. Moreover, the FliA anti-sigma factor FlgM was not secreted in the T6SS mutants, and flgM over-expression reduced both motility and mucoidy. This study provides arguments to unravel the crosstalk between T6SS and motility.

International audience; In many Gram-negative bacteria, virulence, and social behavior are controlled by quorum-sensing (QS) systems based on the synthesis and perception of N-acyl homoserine lactones (AHLs). Quorum-quenching (QQ) is currently used to disrupt bacterial communication, as a biocontrol strategy for plant crop protection. In this context, the Gram-positive bacterium Rhodococcus erythropolis uses a catabolic pathway to control the virulence of soft-rot pathogens by degrading their AHL signals. This QS signal degradation pathway requires the expression of the qsd operon, encoding the key enzyme QsdA, an intracellular lactonase that can hydrolyze a wide range of substrates. QsdR, a TetR-like family regulator, represses the expression of the qsd operon. During AHL degradation, this repression is released by the binding of the γ-butyrolactone ring of the pathogen signaling molecules to QsdR. We show here that a lactone designed to mimic quorum signals, γ-caprolactone, can act as an effector ligand of QsdR, triggering the synthesis of qsd operon-encoded enzymes. Interaction between γ-caprolactone and QsdR was demonstrated indirectly, by quantitative RT-PCR, molecular docking and transcriptional fusion approaches, and directly, in an electrophoretic mobility shift assay. This broad-affinity regulatory system demonstratesthat preventive or curative quenching therapies could be triggered artificially and/or managed in a sustainable way by the addition of g-caprolactone, a compound better known as cheap food additive. The biostimulation of QQ activity could therefore be used to counteract the lack of consistency observed in some large-scale biocontrol assays

Flagella-driven motility is an important trait for bacterial colonization and virulence. Flagella rotate and propel bacteria in liquid or semi-liquid media to ensure such bacterial fitness. Bacterial flagella are composed of three parts: a membrane complex, a flexible-hook, and a flagellin filament. The most widely studied models in terms of the flagellar apparatus are E. coli and Salmonella. However, there are many differences between these enteric bacteria and the bacteria of the Pseudomonas genus. Enteric bacteria possess peritrichous flagella, in contrast to Pseudomonads, which possess polar flagella. In addition, flagellar gene expression in Pseudomonas is under a four-tiered regulatory circuit, whereas enteric bacteria express flagellar genes in a three-step manner. Here, we use knowledge of E. coli and Salmonella flagella to describe the general properties of flagella and then focus on the specificities of Pseudomonas flagella. After a description of flagellar structure, which is highly conserved among Gram-negative bacteria, we focus on the steps of flagellar assembly that differ between enteric and polar-flagellated bacteria. In addition, we summarize generalities concerning the fuel used for the production and rotation of the flagellar macromolecular complex. The last part summarizes known regulatory pathways and potential links with the type-six secretion system (T6SS).

Numerous studies in Gram-negative bacteria have focused on the Type VI Secretion Systems (T6SSs), Quorum Sensing (QS), and social behavior, such as in biofilms. These interconnected mechanisms are important for bacterial survival; T6SSs allow bacteria to battle other cells, QS is devoted to the perception of bacterial cell density, and biofilm formation is essentially controlled by QS. Here, we review data concerning T6SS dynamics and T6SS-QS cross-talk that suggest the existence of inter-bacterial communication via T6SSs.

INTRODUCTION: 80% of French people say they are in favor of dying in their homes. The general practitioner (GP), at the heart of the outpatient management of palliative care, must have tools adapted to the care of his patients. Computerized medical decision support systems exist in many fields, but in the field of palliative care, these tools are inappropriate for the GPs consultation time. OBJECTIVE: To build an appropriate computerized medical decision support system in palliative care, based on a needs study with the Isère’s GPs. METHOD: 1/ Sending of a questionnaire to prioritize the themes to develop. 2/ Writing of the content of the site mockup, based on the existing scientific literature. 3/ Correction of the form by a nominal group answering the question: Is the information of palliaclic.com (the site mockup) clear and adapted to the outpatient practice in palliative care? RESULTS: 289 answers brought out the themes: "Confusion", "Alternative ways of administration", "Dyspnea", "Sedation", "Mixed pain, neuropathic pain, psychogenic pain" and "Local contacts in palliative care". Bibliographic searches were based on Pubmed databases and relevant scholarly societies. Optimizating the shape of the DADM was achieved by bringing together a nominal group of GPs and hospital palliative care practitioners. They evaluated the layout of the site and issued notices that led to modifications. CONCLUSION: This study helped to clarify the needs and expectations of GPs for outpatient palliative care, and to build a computerized medical decision support system compatible with their practice.; INTRODUCTION : 80% des français se disent favorables à décéder dans leur foyer. Le médecin généraliste (MG), au cœur de la prise en charge ambulatoire des soins palliatifs, doit disposer d’outils adaptés à la prise en charge de ses patients. Des Systèmes informatisés d’Aide à la Décision Médicale (SADM) existent dans de nombreux domaines, mais dans celui des soins palliatifs, ces outils sont inadaptés au temps de la consultation du MG. OBJECTIF : Construire un SADM de soins palliatifs approprié, basé sur une étude des besoins auprès des MG de l’Isère. MÉTHODE : 1/ Envoi d’un questionnaire pour prioriser les thématiques à développer. 2/ Rédaction du contenu du SADM en s’appuyant sur la littérature scientifique existante. 3/Correction de la forme par un groupe nominal répondant à la question : L’information de la maquette palliaclic.com (le SADM) est-elle claire et adaptée à la pratique ambulatoire des soins palliatifs? RÉSULTATS : 289 réponses firent ressortir les thématiques: “Confusion”, “Voies d’administrations alternatives”, “Dyspnée”, “Sédation”, “Douleur mixte, neuropathique, psychogène” et “Contacts locaux en soins palliatifs”. Les recherches bibliographiques se sont appuyées sur les bases de données Pubmed et des sociétés savantes concernées. L’optimisation de la forme du SADM s’effectua en réunissant un groupe nominal composé de MG et de praticiens hospitaliers de soins palliatifs. Il évalua la maquette du site et émit des avis qui menèrent à des modifications. CONCLUSION : Cette étude a permis d’éclairer les besoins et les attentes des MG pour les soins palliatifs ambulatoires, et de bâtir un SADM informatisé compatible avec ce mode d’exercice.

Background: In France in 2011, 38.7% of the medical residents suffered of a burnout syndrome. The development of prevention programs suited to their problems seems essential. Objective: To explore the measures of prevention considered by the medical residents of Grenoble themselves. Method: This is a qualitative study using focus groups of medical residents of Grenoble. The sampling was designed to search for maximal variation. A thematic analysis of the verbatim was conducted by triangulation of the searchers, after full written transcription of the focus groups. Results: 5 focus groups were conducted. Eight themes emerged: improve externship, adapt the theoretical training during the internship, improve the working conditions, control the workload, improve the relationships, harmonize work and private life, organize psychological counseling and take into account personality. Some of the preventive measures already exist but need to be applied or generalized: the limit of 48 hours of work per week, promote telephone counseling. Some other measures were totally new: to have an employment contract and a job description for each training course, a replacement system, limited geographic areas for the training courses and create stress management training. Conclusion: The residents who were interrogated proposed multiple preventive measures to prevent the burnout syndrome. Their implementation now requires some efforts from the administrative structures that manage residents.; Contexte : En France en 2011, 38.7% des internes en médecine générale étaient atteints du syndrome d’épuisement professionnel. L'élaboration de programmes de prévention adaptés à leurs problématiques parait indispensable. Objectif : Explorer les moyens de prévention du SEP envisagés par les internes en médecine générale de Grenoble. Méthode : Il s’agit d’une étude qualitative par focus group auprès d’internes en médecine générale de Grenoble. L’échantillonnage a été raisonné en recherche de variation maximale. Une analyse thématique des verbatim a été conduite par triangulation des chercheurs après retranscription intégrale des focus group. Résultats : 5 focus group ont été réalisés. Huit thèmes ont émergé : améliorer l’externat et réformer les concours, adapter la formation théorique pendant l’internat, améliorer le vécu des stages, encadrer la charge de travail des internes, améliorer les relations sociales, harmoniser internat et vie privée, organiser un suivi psychologique et prendre en compte les facteurs personnels. Certains moyens de prévention n’étaient autres que des mesures existantes qui nécessiteraient d’être réellement appliquées ou généralisées : respecter les 48h hebdomadaires, promouvoir les lignes d’écoute téléphonique. D’autres propositions étaient entièrement novatrices : avoir un contrat de travail et une fiche de poste à chaque stage, organiser un système de remplacement, limiter les zones géographiques des stages, créer des cours de gestion du stress. Conclusion : Les internes interrogés ont proposé de nombreuses pistes de prévention du SEP. Leur mise en application demande maintenant des efforts de la part des structures qui les encadrent.