10 research outputs found
Comment répondre aux défis de la phagothérapie en élevage aquacole ?
Avec la nĂ©cessitĂ© de nourrir une population humaine estimĂ©e Ă 9,2 milliards en 2050 [1], les secteurs de lâĂ©levage dont lâaquaculture ont besoin dâune alternative aux antibiotiques dont ils Ă©taient historiquement fortement dĂ©pendants. Parmi les options envisagĂ©es pour rĂ©pondre Ă cette demande, les bactĂ©riophages semblent apporter une rĂ©ponse prometteuse : leur abondance, leur efficacitĂ© ainsi que leur spĂ©cificitĂ© sont autant dâarguments stimulant lâintĂ©rĂȘt quâils suscitent. Le milieux aqueux est de plus avantageux pour la phagothĂ©rapie puisquâil favorise les rencontre entre le virus et son hĂŽte. De nombreux produits Ă base de phages et Ă destination des industries agricoles et agroalimentaires Ă©mergent, tels que le phage anti Listeria monocytogenes P100.Cependant ces virus ne prĂ©sentent pas que des avantages puisque leur utilisation en Ă©levage peut avoir des consĂ©quences Ă©cologiques via la perturbation des Ă©cosystĂšmes microbiens, la diffusion incontrĂŽlĂ©e de gĂšnes de rĂ©sistance aux antibiotiques ou de pathogĂ©nicitĂ©. Les bactĂ©riophages favorisent Ă©galement la propagation de rĂ©sistances chez leurs hĂŽtes et doivent donc ĂȘtre utilisĂ©s avec prĂ©caution [2]. ExceptĂ© chez certains pays, ces antimicrobiens viraux ne rentrent dans aucune dĂ©finition rĂ©glementaire et leur utilisation nâest donc pas autorisĂ©e en Ă©levage (ni en tant quâadditif alimentaire ni en tant que traitement curatif) [3]. Enfin pour parvenir Ă les utiliser dans un cadre industriel, il est important de sâassurer une production sans danger. Ces problĂ©matiques sont similaires pour une utilisation des phages Ă but sani- taire lors de la transformation des aliments.Plusieurs leviers dâactions peuvent ĂȘtre envisagĂ©s pour rĂ©pondre Ă certaines de ces limites : les phages peuvent ĂȘtre associĂ©s en cocktails ou combinĂ©s avec dâautres actifs afin dâaugmenter leur efficacitĂ© et limiter le dĂ©veloppement de rĂ©sistances. Il est Ă©galement possible de les sĂ©lectionner ou dâeffectuer des modifications gĂ©nĂ©tiques pour Ă©liminer les caractĂ©ristiques non dĂ©sirĂ©es. Lâutilisation dâenzymes lytiques (holines et endolysines) au lieu de virions complets est une piste permettant la rĂ©solution des questions dâĂ©changes de matĂ©riel gĂ©nĂ©tique et de rĂ©glementation, puisquâil ne sâagit alors par dĂ©finition plus de virus. Concernant la production de phages, il est nĂ©cessaire dâidentifier une souche de propagation non pathogĂšne afin de produire en sĂ©curitĂ©
Overcoming the challenges of phage therapy for industrial aquaculture: A review
Aquaculture is the fastest-growing sector in food industry. Its development is powered by the intensification ofthe production which increased bacterial disease occurrence and spreading. As aquaculture deeply relies on amassive prophylactic and therapeutic use of antibiotics, it is threatened by the emergence of multi drug resistantbacteria. The stalled development of new antibiotics makes finding new therapeutic solutions a burning issue.Thanks to their specific host range, their ability to treat both the farmed species and the environment, theirlimited ecological impact and their abundance in the environment, bacteriophages represent a promising sustainablesolution to control pathogenic aquaculture bacteria.In this review we discuss the interest of phage biocontrol for aquaculture and how can bacterial resistance,ecological, pharmacological and production related issues be solved
Toxigenic potential and antimicrobial susceptibility of Bacillus cereus group bacteria isolated from Tunisian foodstuffs
International audienceBackground: Despite the importance of the B. cereus group as major foodborne pathogens that may cause diarrheal and/or emetic syndrome(s), no study in Tunisia has been conducted in order to characterize the pathogenic potential of the B. cereus group. The aim of this study was to assess the sanitary potential risks of 174 B. cereus group strains isolated from different foodstuffs by detecting and profiling virulence genes (hblA, hblB, hblC, hblD, nheA, nheB, nheC, cytK, bceT and ces), testing the isolates cytotoxic activity on Caco-2 cells and antimicrobial susceptibility towards 11 antibiotics. Results: The entertoxin genes detected among B. cereus isolates were, in decreasing order, nheA (98.9%), nheC (97.7%) and nheB (86.8%) versus hblC (54.6%), hblD (54.6%), hblA (29.9%) and hblB (14.9%), respectively encoding for Non-hemolytic enterotoxin (NHE) and Hemolysin BL (HBL). The isolates are multi-toxigenic, harbouring at least one gene of each NHE and HBL complexes associated or not to bceT, cytK-2 and ces genes. Based on the incidence of virulence genes, the strains were separated into 12 toxigenic groups. Isolates positive for cytK (37,9%) harbored the cytK-2 variant. The detection rates of bceT and ces genes were 50.6 and 4%, respectively. When bacteria were incubated in BHI-YE at 30°C for 18 h and for 5 d, 70.7 and 35% of the strains were shown to be cytotoxic to Caco-2 cells, respectively. The cytotoxicity of B. cereus strains depended on the food source of isolation. The presence of virulence factors is not always consistent with cytotoxicity. However, different combinations of enterotoxin genetic determinants are significantly associated to the cytotoxic potential of the bacteria. All strains were fully sensitive to rifampicin, chloramphenicol, ciprofloxacin, and gentamycin. The majority of the isolates were susceptible to streptomycin, kanamycin, erythromycin, vancomycin and tetracycline but showed resistance to ampicillin and novobiocin. Conclusion: Our results contribute data that are primary to facilitate risk assessments in order to prevent food poisoning due to B. cereus group
Isolation, caracterization and use of a Vibrio spp. collection in order to develop a phage therapy product for shrimp aquaculture.
DâaprĂšs lâONU, le peuplement humain atteindra 9,7 milliards en 2050. Cette population Ă venir devra ĂȘtre accompagnĂ©e dâune augmentation de la production alimentaire don lâaquaculture est pressentie pour prendre la plus grande part. Le dĂ©veloppement de cette industrie est cependant menacĂ© par la diminution forcĂ©e de lâutilisation dâantibiotiques, qui sont utilisĂ©s pour traiter les maladies bactĂ©riennes comme les vibrioses. Parmi les solutions envisagĂ©es pour remplacer ces derniers, les bacteriophages (phages), qui sont des virus de bactĂ©ries, semblent prometteurs. Lâobjectif du projet dont le travail dĂ©crit dans ce document est la premiĂšre partie est dâobtenir des phages capables de traiter les vibrioses, dans les Ă©levages de crevettes.La premiĂšre Ă©tape de la stratĂ©gie utilisĂ©e est la construction et la caractĂ©risation dâune collection de souches de Vibrio spp. Celle-ci a Ă©tĂ© ensuite utilisĂ©e pour rechercher et caractĂ©riser des phages. Une souchothĂšque de 234 souches de Vibrio spp. a ainsi Ă©tĂ© assemblĂ©e. LâĂ©tude du gĂ©nome de 15 de ses souches a permis la dĂ©couverte de 4 nouvelles espĂšces. Sept variants dâun phage ont Ă©tĂ© isolĂ©s et caractĂ©risĂ©s, notamment par lâĂ©tude de leur gĂ©nome. Le plan de travail expĂ©rimental mis au point, la collection bactĂ©rienne ainsi que les recommandations pour lâobtention de phages dĂ©crites dans ce document sont un premier pas vers le dĂ©veloppement dâun produit de phagothĂ©rapie pour lâentreprise Mixscience.Human population is going to reach 9.7 billion by 2050 according to UN. This growth needs to be followed by an increase in food production, of which aquaculture is foreseen to take the biggest part. Aquaculture industryâs growth is however threatened by the mandatory diminution of antibiotics use, which are used to treat bacterial diseases such as vibriosis. Bacteriophages (phages) are virus infecting bacteria. They are among the most promising antibiotic alternatives for aquaculture. This thesis is part of a Project that aims at gathering phages able to treat vibriosis in shrimp farms. The first step to achieve this was to build and caracterize a Vibrio spp. strain collection, which was then used to obtain phages.A 234 Vibrio spp. Strain colection was therefore built. The study of the genome of 15 strains allowed the discovery of 4 new species. And 7 phage variants were isolated and caracterized, by various techniques including genome analysis. The workflow developped in this study, the bacterial strain collection and the recommandation for phage isolation given in this document are a first step towards the developpment of a phage-based product for Mixscience company
LâIA pour des systĂšmes industriels interopĂ©rables et autonomes
Entretien avec Olivier Boissier, Maxime Lefrançois et Antoine ZIMMERMANN rĂ©alisĂ© par AnaĂŻs Culot pour I'MTech, le Blog recherche de l'Institut Mines-TĂ©lĂ©com.Ă Mines Saint-Ătienne, les chercheurs Olivier Boissier, Maxime Lefrançois et Antoine Zimmermann, sâattaquent Ă la problĂ©matique dâinteropĂ©rabilitĂ© essentielle Ă lâindustrie du futur, grĂące Ă lâIA. La standardisation dâinformations sous forme de graphes de connaissances leur permet de faire interagir des machines aux langages diffĂ©rents. Ils exploitent ensuite ce systĂšme via un rĂ©seau dâagents autonomes distribuĂ©s sur chaque machine pour automatiser une ligne de production
Isolation and Characterization of a Novel Phage Collection against Avian-Pathogenic Escherichia coli
The increase in antibiotic-resistant avian-pathogenic Escherichia coli (APEC), the causative agent of colibacillosis in poultry, warrants urgent research and the development of alternative therapies. This study describes the isolation and characterization of 19 genetically diverse, lytic coliphages, 8 of which were tested in combination for their efficacy in controlling in ovo APEC infections. Genome homology analysis revealed that the phages belong to nine different genera, one of them being a novel genus (Nouzillyvirus). One phage, REC, was derived from a recombination event between two Phapecoctavirus phages (ESCO5 and ESCO37) isolated in this study. Twenty-six of the 30 APEC strains tested were lysed by at least one phage. Phages exhibited varying infectious capacities, with narrow to broad host ranges. The broad host range of some phages could be partially explained by the presence of receptor-binding protein carrying a polysaccharidase domain. To demonstrate their therapeutic potential, a phage cocktail consisting of eight phages belonging to eight different genera was tested against BEN4358, an APEC O2 strain. In vitro, this phage cocktail fully inhibited the growth of BEN4358. In a chicken lethality embryo assay, the phage cocktail enabled 90% of phage-treated embryos to survive infection with BEN4358, compared with 0% of nontreated embryos, indicating that these novel phages are good candidates to successfully treat colibacillosis in poultry.IMPORTANCE Colibacillosis, the most common bacterial disease affecting poultry, is mainly treated by antibiotics. Due to the increased prevalence of multidrug-resistant avian-pathogenic Escherichia coli, there is an urgent need to assess the efficacy of alternatives to antibiotherapy, such as phage therapy. Here, we have isolated and characterized 19 coliphages that belong to nine phage genera. We showed that a combination of 8 of these phages was efficacious in vitro to control the growth of a clinical isolate of E. coli. Used in ovo, this phage combination allowed embryos to survive APEC infection. Thus, this phage combination represents a promising treatment for avian colibacillosis
Isolation of Harveyi clade Vibrio spp. collected in aquaculture farms: How can the identification issue be addressed?
International audienceAquaculture is a fast growing industry with its development hampered by bacterial diseases. Vibriosis caused byHarveyi clade strains is known for causing heavy loss especially in shrimp aquaculture farms. For farm treatmentand pathogen spread management, veterinarians and researchers need reliable bacterial identification tools. Arange of identification methods have been presented for Vibrio spp. in recent literature but little feedback on theirperformance have been made available to this day.This study aims at comparing Vibrio spp. identification methods and providing guidance on their use.Fifty farms were sampled and bacterial colonies were isolated using specific culture media before microscopicanalysis and genomic profiling using ERIC-PCR. A preliminary identification step was carried out using MALDIToFmass spectrometry. Four methods were compared for strain identification on 14 newly isolated Harveyiclade Vibrio spp. strains: whole genome sequencing (digital DNA DNA Hybridization (dDDH)), 5 MLSA schemes,ferric uptake regulation (fur) and lecithin-dependent haemolysin (ldh) single gene based identification methods.Apart from dDDH which is a reference method, no technique could identify all the isolates to the species level.The other tested techniques allowed a faster, cheaper but sub genus clade identification which can be interestingwhen absolute precision is not required. In this regard, MALDI-ToF and fur based identification seemed especiallypromising
Toxigenic potential and antimicrobial susceptibility of Bacillus cereus group bacteria isolated from Tunisian foodstuffs
Catalogue of Geadephaga (Coleoptera: Adephaga) of America, north of Mexico
All scientific names of Trachypachidae, Rhysodidae, and Carabidae (including cicindelines) recorded from America north of Mexico are catalogued. Available species-group names are listed in their original combinations with the author(s), year of publication, page citation, type locality, location of the name-bearing type, and etymology for many patronymic names. In addition, the reference in which a given species-group name is first synonymized is recorded for invalid taxa. Genus-group names are listed with the author(s), year of publication, page citation, type species with way of fixation, and etymology for most. The reference in which a given genus-group name is first synonymized is recorded for many invalid taxa. Family-group names are listed with the author(s), year of publication, page citation, and type genus. The geographical distribution of all species-group taxa is briefly summarized and their state and province records are indicated.One new genus-group taxon, Randallius new subgenus (type species: Chlaenius purpuricollis Randall, 1838), one new replacement name, Pterostichus amadeus new name for Pterostichus vexatus Bousquet, 1985, and three changes in precedence, Ellipsoptera rubicunda (Harris, 1911) for Ellipsoptera marutha (Dow, 1911), Badister micans LeConte, 1844 for Badister ocularis Casey, 1920, and Agonum deplanatum Ménétriés, 1843 for Agonum fallianum (Leng, 1919), are proposed. Five new genus-group synonymies and 65 new species-group synonymies, one new species-group status, and 12 new combinations (see Appendix 5) are established.The work also includes a discussion of the notable private North American carabid collections, a synopsis of all extant world geadephagan tribes and subfamilies, a brief faunistic assessment of the fauna, a list of valid species-group taxa, a list of North American fossil Geadephaga (Appendix 1), a list of North American Geadephaga larvae described or illustrated (Appendix 2), a list of Geadephaga species described from specimens mislabeled as from North America (Appendix 3), a list of unavailable Geadephaga names listed from North America (Appendix 4), a list of nomenclatural acts included in this catalogue (Appendix 5), a complete bibliography with indication of the dates of publication in addition to the year, and indices of personal names, supraspecific names, and species-group names