https://hdl.handle.net/20.500.12177/70 2026-07-29T17:43:03Z https://hdl.handle.net/20.500.12177/13903 Title: Identification et prévention des moisissures sur milieu de culture malt extract Agar (MEA) et quelques aliments couramment consommés dans la Region du Centre Authors: Zang, Paul Castro Mathys Abstract: This study aimed at three different objectives including a contribution to the identification of food fungi on some currently consumed foodstuff in the center région with particular attention to some bakery product such as bread and cakes on the hand, and cassava “bâton” (popularly known as “bobolo”) on the other hand. The influence of température on the time of conservation of these food items as well as the time of incubation before occurrence of spontaneous molds on freshly prepared MEA culture medium were also assessed. Température of conservation included room température (averagely 25°C) and conservation in the refrigerator (4°C to 8°C). After isolation of molds on these food items and their cultivation on MEA and thereafter as slide cultures; microscopie and macroscopie descriptions were done on structures observed in order to identify the fungal flora that grows in both types of conservation as well as for spontaneous molds growth on MEA. The experiment conducted at room température led to the identification on the above mentioned foot items of molds belonging to three généra including Aspergillus, Rhizopus and Tricoderma and only Aspergillus was isolated from some of these items conserved in the refrigerator. Aspergillus sp and Ulocladium sp were recorded as spontaneous molds growing on MEA culture medium with major différences in the time of occurrence at room température and in the refrigerator. Ail the food items including bread, cakes, and cassava “bâton” never showed mouldy contaminations. The time of incubation at room température for appearance of the first signs of molds was 3 to 4 days on bakery products including bread and cakes and 6 to 8 days for cassava “bâton”. In the refrigerator this time was extended to 26 to 30 days for bakery products and far over 30 days for cassava “bâton”. Ail in ail, this work led to several key remarks, the first being that without fully preventing the growth of molds on the food items tested, low température (4°C to 8°C) of réfrigération enables to reduce the diversity of the contaminating microfungi on these food items. Also this range of réfrigération (4°C to 8°C) température enables to extend by more than 3 weeks the time of conservation of bakery products (bread and cake) compared to room température and by more than 30 days the conservation of cassava “bâton”. Also the incubation period before appearance of spontaneous molds on MEA culture medium is also extended by more than 3 weeks in refrigerator compared to conservation at room température. 2019-01-01T00:00:00Z https://hdl.handle.net/20.500.12177/13902 Title: Évaluation de l’activité antibactérienne des extraits de champignons endophytes isolé de Macaranga hurifolia Beille et Voacanga thouarsii Roem. & Schult, sur quelques bactéries responsables des infections respiratoires. Authors: Fofou Tandzong, Carmel Abstract: Respiratory infections are among the leading causes of infant mortality, representing a significant public health concern worldwide. The emergence of antibiotic-resistant strains in the context of unsuccessful treatment has prompted the development of novel therapeutic strategies. This study aims to assess the antibacterial activity of extracts from endophytic fungi of M. hurifolia and V. thouarsii against some respiratory tract pathogens. To this end, the leaves, bark, and wood of M. hurifolia and V. thouarsii were collected in Nkolbisson, Yaoundé, Cameroon, and identified at the National Herbarium. Subsequently, the plant material underwent a series of surface decontaminations, followed by inoculation into a PDA medium to obtain pure cultures. The cultures were identified on the PDA, SDA, and CDA media based on their morphological characteristics. The extraction of secondary metabolites was conducted using acetic ethyl acetate following the cultivation of the mushrooms in a rye-based medium. Subsequently, the inhibition tests (CMI and CMB) were conducted on the mycobacterial strains (BCG and H37RV ATCC 27294) and the Gram positive bacterial strains (S. aureus NCTC 12973, H. influenzae ATCC 49247, K. pneumoniae ATCC 17102, P. aeruginosa ATCC 76110, and E. coli ATCC 25922) using the microdilution method in liquid medium. The different classes of secondary metabolites present in the active extracts were identified through colorimetric tests. The results demonstrate that of the twenty-eight (28) characterized fungi, twenty-four (24) were identified as belonging to the following genera: Geotrichum (05), Neoscytalidium (05), Acremonium (04), Fusarium (04), Lasiodiplodia (04), Absidia (01), and Penicillium (01), with four (04) isolates remaining unidentified. Eight (08) fungal endophyte extracts were produced from these isolates. Extract “E11” demonstrated the greatest activity against all bacterial strains tested, with CMIs values ranging from 0.39 mg/mL against BCG and Pseudomonas aeruginosa strains to 1.56 mg/mL against the remaining bacterial strains. The chemical screening revealed the presence of flavonoids, phenols, polyphenols, saponins, and anthraquinones in all extracts. 2025-01-01T00:00:00Z https://hdl.handle.net/20.500.12177/13901 Title: Pétrologie des péridotites de tello (plateau de l’Adamaoua) : prospection géochimique du platine et du palladium Authors: Guiswe, Abaitouin Abstract: Tello is a locality in the Adamaoua region, some 50 km from Ngaoundéré, the regional capital, where peridotite caves outcrop. These peridotites were studied as part of geochemical prospecting (platinum and palladium). The Tello peridotites are greenish, dense, with a vacuolar structure and protogranular texture, composed of olivine orthopyrosene, clinopyrosene and spinel They are characteristic of ultrabasic rocks, with moderate and slightly variable SiO2 and MgO contents, low Fe2O3,Al2O3. The sum of alkalis and alkaline earths (Na O+K O+CaO+MgO) 22 varies slightly between 45%. They also contain very high levels of Cr, Ni, and Co. The elements Sr, Ba , Zr and Cu are moderate. levels of Nb (1.12- 2.5 ppm) and Ga (1.19-2.36 ppm) are very low. Other trace elements are very low, below 2 ppm. As for rare earths, the sum of their contents varies between 4 and 10 ppm, with high levels of Ce and Nd. The other rare earths have very low contents of less than 1 ppm. The sum of LREE contents is higher than that of HREE (0.38-0.83), with LREE /HREE ratios ranging from 6 and 15 ppm, hence an enrichment in LREE compared to HREE. Ce/Ce* and Eu/Eu* values are roughly equal to 1 ppm, and (La/Yb)N ratios range from 6 and 23ppm. Normalization of the rare earths with respect to the primitive mantle shows that in all samples, the rare earths have a similar behavior in Tello peridotites. Platinum Group elements with high contents in the samples are Ru (4-6 ppm); Pt (>3ppm). This incompatibility between gold and PGE would be due to the fact that they would not concentrate in the same mineral phases. The Rhodium, palladium and osmium are very mobility of PGMs in the Tello peridotites. Thus, geochemical prospecting for gold and platinum-group elements shows that grades are of little interest in the Tello peridotites 2024-01-01T00:00:00Z https://hdl.handle.net/20.500.12177/13900 Title: knowledge, attitude and practices of hygiene and sanitation by street food vendors and impacts on consumers health in the Biyem Assi and obili Yaoundé Cameron Authors: Akumachi, Glory Zee Abstract: La nourriture englobe tout ce qui, une fois ingéré, fournit des nutriments essentiels au corps. La vente de nourriture de rue implique des aliments et boissons prêts à consommer, souvent préparés dans des lieux publics tels que les rues et les gares. L'Organisation mondiale de la santé (OMS) a identifié cinq principes clés pour garantir une alimentation sûre : maintenir la propreté, séparer les aliments crus des cuits, bien cuire, conserver les aliments à des températures sûres, et utiliser de l'eau et des matières premières sûres. Environ 600 millions de cas de maladies d'origine alimentaire sont liés à de mauvaises pratiques d'hygiène, entraînant environ 420 000 décès chaque année. Cette étude visait à analyser les pratiques d'hygiène et d'assainissement des vendeurs de nourriture de rue et leur impact sur la santé des consommateurs dans les communautés de Biyem Assi et Obili à Yaoundé, Cameroun. Une étude descriptive transversale, utilisant des méthodes qualitatives et quantitatives, a été réalisée. Des questionnaires structurés ont été distribués à 250 participants (100 vendeurs, 50 consommateurs, 50 professionnels de santé, 50 vendeurs au détail) pour évaluer leurs connaissances et pratiques en matière d'hygiène. La majorité des participants étaient jeunes, avec une proportion plus élevée de femmes .Les résultats montrent que 78 % des vendeurs connaissaient les principes d'hygiène, mais seulement 29 % adoptaient des pratiques d'hygiène personnelle et environnementale. Environ 66 % des consommateurs ont signalé des problèmes de santé après avoir consommé de la nourriture de rue, bien que les maladies d'origine alimentaire n'étaient pas les principales causes de visites aux cliniques. Les problèmes de santé les plus fréquents étaient le paludisme (42 %) et la typhoïde (34 %). Les conclusions de l'étude indiquent que, malgré une connaissance des pratiques d'hygiène, les vendeurs ne les appliquent pas suffisamment, ce qui impacte la santé des consommateurs. Les chercheurs recommandent des formations continues sur l'hygiène alimentaire et des contrôles réguliers pour les vendeurs, ainsi qu'une sensibilisation accrue à l'hygiène pour le grand public. 2023-01-01T00:00:00Z