Détermination d’une couche superficielle de sol favorable au transfert du Trichloréthylène (TCE) vers l’atmosphère

L’intérêt de cet article est de montrer qu’il existe une couche superficielle dans la zone non saturée du sol à l’intérieur de laquelle les mécanismes de transport du trichloréthylène (TCE) vers l’atmosphère sont favorables. En prenant en compte dans un modèle de simulation certains paramètres clés du sol déterminés expérimentalement, on a pu non seulement montrer que les effets hygroscopiques modifient le comportement du TCE mais aussi et surtout que ces mécanismes de transfert sont plus favorables dans une couche limite qu’on a appelée couche superficielle. Les résultats montrent clairement que les transferts sont plus importants dans une couche limite du sol au de-là de laquelle ce transfert s’amenuise. En d’autres termes, l’atmosphère ambiante influence les mécanismes d’évaporation par l’intermédiaire de la température et de l’humidité relative lorsque celui-ci se trouve dans la couche dite couche superficielle. En revanche, cette influence de l’atmosphère ambiante se réduit à mesure que le TCE s’infiltre en profondeur. Au de-là de 0,8 mètre de profondeur, le milieu ambiant semble jouer un rôle moins important et les mécanismes d’atténuation naturelles sont d’avantage très faibles favorisant ainsi la persistance du TCE dans le sol.Mots-clés : couche superficielle, trichloréthylène, transfert, sol, atténuation naturelle

Survie et performances de croissance des pintadeaux en milieu contrôlé au nord du Burkina Faso

Au Burkina Faso, les pintadeaux connaissent une très forte mortalité liée à des causes multifactorielles, et leur vitesse de croissance reste encore méconnue par les techniciens, tant de la recherche que du développement. Cette étude vise à évaluer les performances de croissance et le taux de mortalité des pintadeaux dans les conditions d’élevage améliorées. Le maximum du poids des oeufs incubés est compris dans la catégorie de 40-45 g. Les de mensurations des oeufs ont révélé une longueur moyenne de 47,4 ± 1,428 mm et 38,65 ± 1,08 mm en moyenne pour le grand diamètre. Le taux de mortalité a été de 9,10%, 7,00% et 9,80%  respectivement chez le producteur I, II et III avec une moyenne de 8,63%. Le poids vifs des pintadeaux à l’éclosion est de 26,59 ± 2,77 g pour les deux sexes. Pour les femelles, il est de 27,69 ± 2,18g et de 25,48 ± 3,35 g pour les mâles. La courbe de croissance des femelles est largement au dessus de celle des mâles. Les pintadeaux femelles ont un GMQ de 2,84 g et les pintadeaux mâles de 2,27 g pendant les deux premières semaines. Le Gain Moyen Quotidien est de 3,78 g pendant les quatre mois. Le test révèle un effet positif du protocole sur la mortalité des pintadeaux.Mots-clés : Pintadeaux, mortalité, croissance, Burkina Faso

Influence of soy fortification on microbial diversity during cassava fermentation and subsequent physicochemical characteristics of garri

This study investigated the influence of the addition of soy products on the microbiology, nutritional and physico-chemical characteristics of garri, a fermented cassava product. Malted soy flour (MSF) and soy protein (SP) were separately added (12% w/w) to cassava mash prior to controlled fermentation, while non-supplemented cassava mash served as a control. Identification of lactic acid bacteria (LAB) and aerobic mesophilic bacteria was accomplished by repetitive sequence based (rep)-PCR analysis and 16S rRNA gene sequencing. Physicochemical, nutritional and sensory characterisation of control and soy-fortified garri was performed using conventional methods. rep-PCR allowed differentiation of 142 isolates into 41 groups corresponding to 6 species of LAB and 25 species of aerobic mesophiles. LAB isolates belonged to the genera Lactobacillus, Weissella, Leuconostoc and Lactococcus with Leuconostoc mesenteroides being the dominant species in control and MSF-cassava while Weissella cibaria dominated SP-cassava fermentation. Aerobic mesophiles included Gram positive and negative bacteria such species of the genera Bacillus, Clostridium, Staphylococcus, Serratia, Acinetobacter and Raoultella. Diversity of aerobic mesophiles varied between control, MSF- and SP- cassava mash. Protein content of soy-fortified garri increased from 0.73% to 10.17% and 10.05% in MSF and SP garri respectively with a significant decrease in total cyanide from 26 to 11 ppm. Results from physicochemical and organoleptic evaluation indicate that supplementation of cassava with soy products prior to fermentation can produce acceptable garri. Soy products can be considered a viable option for protein fortification of garri, a low protein food with the aim of combating malnutrition

Faecal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae in healthy volunteers and hospitalized patients in Ouagadougou, Burkina Faso: prevalence, resistance profile, and associated risk factors

Background: Extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) are a serious challenge to patients’ treatment. The aim of this study is to determine the prevalence of ESBL-PE, investigate the associated resistance, and analyze the associated risk factors for acquisition of ESBL-PE.Methodology: A cross-sectional study was conducted on healthy volunteers and inpatients. After obtaining informed consent, rectal swabs were collected from each participant for isolation of Enterobacteriaceae on Hektoen enteric agar containing 4µg/L cefotaxime. The Enterobacteriaceae isolates were identified using biochemical tests and ESBL production was confirmed by the double-disc synergy test of amoxicillin and clavulanic acid. Antibiotic susceptibility test of each isolate was done by the disc diffusion method and interpreted using the recommendations of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) clinical  breakpoints version 5.0.Results: During the study period, prevalence of faecal ESBL-PE among the study participants was 54.5% (103/189); 53.5% among healthy volunteers and 55.7% among inpatients (p=0.87). The major ESBL-PE isolates was Escherichia coli (71%) followed by Klebsiella pneumoniae (16%). The isolates in hospitalized patients were resistant to norfloxacin (84.2%), cotrimoxazole (89.5%), and gentamicin (7.0%). The isolates from healthy volunteers were resistant to norfloxacin (86.2%), cotrimoxazole (82.8%), and gentamicin (1.7%).Gender, age, and previous antibiotic use were not significantly associated with carriage of ESBL-PE (p=0.51).Conclusion: The high prevalence of ESBL-PE in this study is worrying. There is an urgent need to develop measures to monitor and limit the spread of these multidrug-resistant organisms in healthcare facilities and the community in Burkina Faso. Keywords: faecal carriage, ESBL-PE, healthy volunteers, inpatients, Burkina Fas

Differentiation of Bacillus pumilus and Bacillus safensis using MALDI-TOF-MS

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) despite being increasingly used as a method for microbial identification, still present limitations in which concerns the differentiation of closely related species. Bacillus pumillus and Bacillus safensis, are species of biotechnological and pharmaceutical significance, difficult to differentiate by conventional methodologies. In this study, using a well-characterized collection of B. pumillus and B. safensis isolates, we demonstrated the suitability of MALDI-TOF-MS combined with chemometrics to accurately and rapidly identify them. Moreover, characteristic species-specific ion masses were tentatively assigned, using UniProtKB/Swiss-Prot and UniProtKB/TrEMBL databases and primary literature. Delineation of B. pumilus (ions at m/z 5271 and 6122) and B. safensis (ions at m/z 5288, 5568 and 6413) species were supported by a congruent characteristic protein pattern. Moreover, using a chemometric approach, the score plot created by partial least square discriminant analysis (PLSDA) of mass spectra demonstrated the presence of two individualized clusters, each one enclosing isolates belonging to a species-specific spectral group. The generated pool of species-specific proteins comprised mostly ribosomal and SASPs proteins. Therefore, in B. pumilus the specific ion at m/z 5271 was associated with a small acid-soluble spore protein (SASP O) or with 50S protein L35, whereas in B. safensis specific ions at m/z 5288 and 5568 were associated with SASP J and P, respectively, and an ion at m/z 6413 with 50S protein L32. Thus, the resulting unique protein profile combined with chemometric analysis, proved to be valuable tools for B. pumilus and B. safensis discrimination, allowing their reliable, reproducible and rapid identification.Dr. Kasthuri Venkateswaran, Dr. Irene Ouoba, Dr. Joseph W. Kloepper, Dr. Cecilie From and Dr. Maria Morea are gratefully acknowledged for providing isolates FO-36bT, SAFN-027, SAFN-037, KL-052, 51-3C and 82-2C; Bs31; SE 49 (AP3) and SE 52 (AP7); FEL 55, UNG22 and MIL46, respectively. Raquel Branquinho was supported by a PhD fellowship (Ref. SFRH/BD/61410/2009) and Clara Sousa by a post-doctoral fellowship (Ref. SFRH/BPD/70548/2010), from FCT (Fundacao para a Ciencia e Tecnologia, Portugal). Hugo Osorio acknowledges the funding from QREN-FEDER through the Operational Program ON. 2 - O Novo Norte. IPATIMUP is an Associate Laboratory of the Portuguese Ministry of Science, Technology and Higher Education and is partially supported by the Portuguese Foundation for Science and Technology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competin

Antibiotic resistance determinants in the interplay between food and gut microbiota

A complex and heterogeneous microflora performs sugar and lactic acid fermentations in food products. Depending on the fermentable food matrix (dairy, meat, vegetable etc.) as well as on the species composition of the microbiota, specific combinations of molecules are produced that confer unique flavor, texture, and taste to each product. Bacterial populations within such “fermented food microbiota” are often of environmental origin, they persist alive in foods ready for consumption, eventually reaching the gastro-intestinal tract where they can interact with the resident gut microbiota of the host. Although this interaction is mostly of transient nature, it can greatly contribute to human health, as several species within the food microbiota also display probiotic properties. Such an interplay between food and gut microbiota underlines the importance of the microbiological quality of fermented foods, as the crowded environment of the gut is also an ideal site for genetic exchanges among bacteria. Selection and spreading of antibiotic resistance genes in foodborne bacteria has gained increasing interest in the past decade, especially in light of the potential transferability of antibiotic resistance determinants to opportunistic pathogens, natural inhabitants of the human gut but capable of acquiring virulence in immunocompromised individuals. This review aims at describing major findings and future prospects in the field, especially after the use of antibiotics as growth promoters was totally banned in Europe, with special emphasis on the application of genomic technologies to improve quality and safety of fermented foods

Is diet partly responsible for differences in COVID-19 death rates between and within countries?

Correction: Volume: 10 Issue: 1 Article Number: 44 DOI: 10.1186/s13601-020-00351-w Published: OCT 26 2020Reported COVID-19 deaths in Germany are relatively low as compared to many European countries. Among the several explanations proposed, an early and large testing of the population was put forward. Most current debates on COVID-19 focus on the differences among countries, but little attention has been given to regional differences and diet. The low-death rate European countries (e.g. Austria, Baltic States, Czech Republic, Finland, Norway, Poland, Slovakia) have used different quarantine and/or confinement times and methods and none have performed as many early tests as Germany. Among other factors that may be significant are the dietary habits. It seems that some foods largely used in these countries may reduce angiotensin-converting enzyme activity or are anti-oxidants. Among the many possible areas of research, it might be important to understand diet and angiotensin-converting enzyme-2 (ACE2) levels in populations with different COVID-19 death rates since dietary interventions may be of great benefit.Peer reviewe

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe