Assessment of Enterococcus durans F21 Isolated from Lben, a Moroccan Fermented Milk as a Biopreservative Agent

Abstract  Background and Objective: Lactic acid bacteria used in food processing for a long time are known for their benefits to consumers and their ability to produce natural antimicrobial compounds used as bio-preservatives in foods. The aim of the present study was the characterization and assessment of F21 strain, isolated from Lben (a traditional Moroccan fermented milk), as food biopreservative. Material and Methods: Isolate F21 was isolated from Lben, subjected to screening of inhibitory activity production, and identified based on morphological, biochemical and molecular identification. Then, the production and physicochemical characterization of the antagonistic substance were determined. Also, the safety profiling and biotechnological properties of isolate were evaluated. Finally, a biopreservative powder with antimicrobial activity was produced and assessed in various food systems (milk, ground beef and fresh cheese). Results and Conclusion: Of the isolated lactic acid bacteria, Enterococcus durans F21, isolated from Lben (a traditional Moroccan fermented milk), was remarkably endowed with interesting enterocin-like substance (heat stable and pH resistant) active against potentially pathogens and food spoilages (Listeria monocytogenes, Listeria innocua, Enterococcus faecalis, Brochothrix thermosphacta, and Mycobacterium smegmatis). Concerning the safety properties, Enterococcus durans F21 was not hemolytic, sensible to antibiotics tested, unable to produce biogenic amines and other virulence enzymes (gelatinase, DNase and urease). In addition, Enterococcus durans F21 showed satisfactory biotechnological characteristics such as acidification power, exopoly-saccharides production and antioxidant activity. The biopreservative powder containing enterocin-like substance F21 that was achieved via freeze-drying showed a minimum inhibition concentration of 60 AU ml-1 against Listeria monocytogenes in culture media. In addition, this biopreservative powder (at 665 AU ml-1) was able to improve safety and shelf-life of numerous foods (milk, Jben and ground beef). Thus, these results provided foundations for further uses of Enterococcus durans F21 as producer of potential food biopreservative agent. Conflict of interest: The authors declare no conflict of interest

Induction of a Peptide with Activity against a Broad Spectrum of Pathogens in the Aedes aegypti Salivary Gland, following Infection with Dengue Virus

The ultimate stage of the transmission of Dengue Virus (DENV) to man is strongly dependent on crosstalk between the virus and the immune system of its vector Aedes aegypti (Ae. aegypti). Infection of the mosquito's salivary glands by DENV is the final step prior to viral transmission. Therefore, in the present study, we have determined the modulatory effects of DENV infection on the immune response in this organ by carrying out a functional genomic analysis of uninfected salivary glands and salivary glands of female Ae. aegypti mosquitoes infected with DENV. We have shown that DENV infection of salivary glands strongly up-regulates the expression of genes that encode proteins involved in the vector's innate immune response, including the immune deficiency (IMD) and Toll signalling pathways, and that it induces the expression of the gene encoding a putative anti-bacterial, cecropin-like, peptide (AAEL000598). Both the chemically synthesized non-cleaved, signal peptide-containing gene product of AAEL000598, and the cleaved, mature form, were found to exert, in addition to antibacterial activity, anti-DENV and anti-Chikungunya viral activity. However, in contrast to the mature form, the immature cecropin peptide was far more effective against Chikungunya virus (CHIKV) and, furthermore, had strong anti-parasite activity as shown by its ability to kill Leishmania spp. Results from circular dichroism analysis showed that the immature form more readily adopts a helical conformation which would help it to cause membrane permeabilization, thus permitting its transfer across hydrophobic cell surfaces, which may explain the difference in the anti-pathogenic activity between the two forms. The present study underscores not only the importance of DENV-induced cecropin in the innate immune response of Ae. aegypti, but also emphasizes the broad-spectrum anti-pathogenic activity of the immature, signal peptide-containing form of this peptide

ERS International Congress 2023: highlights from the Epidemiology and Environment Assembly

In this article, early career members of the Epidemiology and Environment Assembly of the European Respiratory Society (ERS) summarise a selection of four poster and oral sessions from the ERS 2023 Congress. The topics covered the following areas: micro-and macro-environments and respiratory health, occupational upper and lower airway diseases, selected tobacco and nicotine research, and multimorbidity in people with lung diseases. The topics and studies covered in this review illustrate the broad range of the multifaceted research taking place within Assembly 6, from the identification of indoor and outdoor environmental risk factors for the development and worsening of respiratory diseases to the concerningly increasing use of nicotine products and their health consequences beyond respiratory health and comorbidity in respiratory diseases

La construction du site pédagogique numérique CHIMACTIV : analyse d'une coopération réussie entre enseignants

International audienceUn collectif d'enseignants inter-établissements s'est organisé pour concevoir et co-construire un site pédagogique numérique. L'équipe de conception initiale a fortement coopéré (au sein de chaque établissement et entre établissements) et interagi étroitement avec différents acteurs (cellules TICE, étudiants, prestataires externes) pour aboutir à une version bilingue du site. La volonté d'élargir et de diversifier le champ des utilisateurs (enseignants et étudiants) a conduit à ouvrir ce collectif à de nouveaux enseignants, afin de faire évoluer le site et compléter son contenu. Après une analyse de l'organisation mise en place, nous discuterons des obstacles à surmonter, des facteurs de réussite et du ressenti des enseignants ayant vécu cette coopération, avant de conclure sur ce qu'apporte l'aspect « numérique » des ressources développées dans la coopération entre enseignants sur la base de notre expérience

De novo TBR1 variants cause a neurocognitive phenotype with ID and autistic traits:report of 25 new individuals and review of the literature

TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands

Cytoplasmic Incompatibility as a Means of Controlling Culex pipiens quinquefasciatus Mosquito in the Islands of the South-Western Indian Ocean

The use of the bacterium Wolbachia is an attractive alternative method to control vector populations. In mosquitoes, as in members of the Culex pipiens complex, Wolbachia induces a form of embryonic lethality called cytoplasmic incompatibility, a sperm-egg incompatibility occurring when infected males mate either with uninfected females or with females infected with incompatible Wolbachia strain(s). Here we explore the feasibility of the Incompatible Insect Technique (IIT), a species-specific control approach in which field females are sterilized by inundative releases of incompatible males. We show that the Wolbachia wPip(Is) strain, naturally infecting Cx. p. pipiens mosquitoes from Turkey, is a good candidate to control Cx. p. quinquefasciatus populations on four islands of the south-western Indian Ocean (La Réunion, Mauritius, Grande Glorieuse and Mayotte). The wPip(Is) strain was introduced into the nuclear background of Cx. p. quinquefasciatus mosquitoes from La Réunion, leading to the LR[wPip(Is)] line. Total embryonic lethality was observed in crosses between LR[wPip(Is)] males and all tested field females from the four islands. Interestingly, most crosses involving LR[wPip(Is)] females and field males were also incompatible, which is expected to reduce the impact of any accidental release of LR[wPip(Is)] females. Cage experiments demonstrate that LR[wPip(Is)] males are equally competitive with La Réunion males resulting in demographic crash when LR[wPip(Is)] males were introduced into La Réunion laboratory cages. These results, together with the geographic isolation of the four south-western Indian Ocean islands and their limited land area, support the feasibility of an IIT program using LR[wPip(Is)] males and stimulate the implementation of field tests for a Cx. p. quinquefasciatus control strategy on these islands

Interaction between the endosymbiotic bacteria Wolbachia and mosquitoes of the Culex pipiens complex : from bacterial genomes to host population’s structuring

Wolbachia est une bactérie endosymbiotique, intracellulaire et exclusivement transmise maternellement qui infecterait au moins 106 espèces d'insectes. Wolbachia manipule fréquemment la reproduction de ses hôte à son avantage, notamment en induisant une forme de stérilité conditionnelle appelée incompatibilité cytoplasmique (IC). Chez les moustiques du complexe Culex pipiens, une grande diversité de souches de Wolbachia et de types d'IC a été précédemment identifiée, mais plusieurs aspects de la biologie de cette association restaient peu connus. Les travaux présentés dans cette thèse ont notamment permis de caractériser (i) l'impact de Wolbachia sur la structuration génétique des populations hôtes et (ii) la diversité des souches de Wolbachia et, plus précisément d'appréhender le mécanisme de l'IC. Par un suivi de populations naturelles, nous avons mis en évidence que Wolbachia induisait une forte structuration de la diversité mitochondriale, mais aussi qu'elle participait à des événements répétés d'introgression cytoplasmique entre les différents membres du complexe Cx. pipiens. Nous avons également mené une étude de génomique comparative basée sur le séquençage de quatre génomes complets de Wolbachia très proches phylogénétiquement. Pour cela, nous avons mis en place une série d'analyses approfondies utilisant un large panel d'outils bioinformatiques couplés à des vérifications moléculaires. Nous avons montré qu'il existait peu de polymorphisme entre les groupes de Wolbachia infectant Cx. pipiens. De plus, ces études nous ont permis de mettre en évidence des gènes candidats qui pourraient être directement impliqués dans le mécanisme de l'IC.Wolbachia is an intracellular bacterial symbiont, exclusively maternally inherited, infecting at least 106 species of insects. Wolbachia commonly manipulates insect reproduction to its own advantage, as well illustrated by a phenomenon of conditional sterility called cytoplasmic incompatibility (CI). In mosquitoes of Culex pipiens complex, a great diversity of Wolbachia strains and of CI types was previously identified, but several aspects of the biology of this symbiotic association remained unknown. The aim of the studies presented in this thesis is to characterize (i) the impact of Wolbachia on the host genetic structure and (ii) the Wolbachia strains diversity in order to attempt an identification of CI molecular basis. By a survey of natural populations, we highlighted that Wolbachia deeply impacts the population structure of mitochondrial diversity, but is also associated with repeated events of cytoplasmic introgression between members of complex Cx. pipiens. We also conducted a study of comparative genomics based on the sequencing of four complete genomes of very closely related Wolbachia strains. For that purpose, we performed a series of analyses using a wide panel of bioinformatic tools coupled with molecular validations. We showed a low polymorphism between two groups of Wolbachia infecting Cx. pipiens. These studies also allowed us to highlight promising candidate genes which could be directly involved in the CI mechanism

Listeria monocytogenes : Caractérisation fonctionnelle d'un mutant ferritine. Etude de la biodiversité par une approche protéomique

Listeria monocytogenes is the etiologic agent of listeriosis a foodborne infection rare but with a case fatality rate of 25% for humans. We have first characterized a ferritin mutant and shown the importance of this gene product in virulence, resistance to conditions of iron starvation and thermal or oxydative stresses. Then, we studied the biodiversity of L. monocytogenes, with a proteomic approach, by studying 12 strains of different origins, serovars and levels of virulence. Based on the intracellular and secreted protein patterns, a hierarchical clustering showed two distinct clusters, one including strains of serovar 1/2a, the other one strains of serovar 4b and 1/2b. Some protein spots either strain- or serovar-specifics were identified by MALDI-TOF mass spectrometry with the objective to better evaluate and manage the risk due to L. monocytogenes.Listeria monocytogenes est l'agent étiologique de la listériose, une infection d'origine alimentaire peu fréquente mais avec un taux de mortalité de 25% chez l'homme. Nous avons d'abord caractérisé un mutant ferritine et montré l'importance du produit de ce gène dans la virulence, la résistance à des conditions de carence en fer et de stress thermique ou oxydatif. Nous nous sommes ensuite intéressés à la biodiversité de L. monocytogenes, par une approche protéomique, en étudiant 12 souches d'origines, de sérovars et de niveaux de virulence variés. Sur la base des profils des protéines intracellulaires et sécrétées, une classification hiérarchique a montré deux groupes distincts, l'un comprenant les souches de sérovar 1/2a, l'autre les souches de sérovar 4b et 1/2b. Des spots protéiques spécifiques de chaque souche et des différents sérovars ont été identifiés par spectrométrie de masse MALDI-TOF avec pour objectif de mieux hiérarchiser et gérer le risque dû à L. monocytogenes