Understanding of Cultivability of <em>Escherichia coli</em> in Aquatic Microcosm in the Presence of Some Plant Extracts for Possible Treatment of Bacterio-Contaminated Water

Escherichia coli (E. coli) is a bacterial indicator of sanitary and hygienic importance widely used in the evaluation of the quality of drinking water, mainly because they are easy to detect and enumerate in water. Its presence in water reflects a deterioration in water quality. The E. coli species is heterogenous in its biotypes, serotypes and lysotypes as in its ecology and its association with pathologies. Studies have reported several cases of infections, sometimes even fatal, caused by contact or consumption of water contaminated by pathogenic strains of E. coli. The detection of E. coli in surface water was shown in field studies to have significant information about the microbial quality of water contaminated with enteric pathogens. Studies using the properties of plant extracts for the inhibition of this bacterium have been widely carried out. Some studies show the potential exploitation of Artemisia annua, Eucalyptus microcorys and Moringa Oleifera extracts treatment of bacterio-contaminated water. The effect of some aqueous extracts on planktonic cells of E. coli in the planktonic and adhered state are summarized in this chapter

Bioqualité Des Formes De Dissémination Des Protozoaires Flagellés Entériques Dans Les Eaux Souterraines (Sources Et Puits) En Zone Anthropisée (Yaoundé-Cameroun)

With an aim of characterizing the cysts of flagellated enteric protozoa present in groundwater of the town of Yaoundé, a descriptive and analytical study was carried out from February to July 2015 on the samples of 6 springs and 6 wells in 6 quarters of the city. The physico-chemical analysis proceeded at the same time on the field and at the laboratory. The observation of the cysts of the flagellated protozoa was done under the inverted microscope of mark Olympus CK2 to the objective 40X after concentration of the samples according to the method of sedimentation and the method of floating. The physicochemical analysis revealed slightly acid water (6, 04 ± 0, 49 U.C), average mineral-bearing (533, 70 ± 346, 18 µS/cm) and rich in suspended matter (14, 14 ± 11, 35 mg/L). The biological analyses revealed the presence of the cysts of the flagellated Protozoa with average densities of 162±115 cysts/L for Giardia intestinalis, 262 ± 280 cysts /L for Chilomastix mesnili, 89±101 cysts /L for Enteromonas hominis and 72 ± 80 cysts /L for Retortamonas intestinalis. In general, the greatest densities of cysts were recorded during the rainy season. The statistical tests revealed positive correlation between the cystic densities with MES, the color, turbidity and the organic matter (p &lt; 0,05), and also negative correlation with nitrate (p &lt; 0,05).This very high parasitological pollution makes water unfit for consumption. The use of untreated spring waters and wells could constitute a significant heath for the households living in the zone of study

Peuplement phytoplanctonique et qualité des eaux en milieu lacustre anthropisé: Cas du lac municipal de Yaoundé (Cameroun)

An annual qualitative and quantitative evaluation of phytoplankton and chlorophylla, as well as of some physico-chemical parameters were recorded in the Yaounde Municipal Lake. Physico-chemical measurements were also regularly done in its main tributary (Mingoa stream). The study aimed at demonstrating the cultural eutrophication of this lake. The discharge of untreated urban effluents into the lake seriously threatens his health state. Indeed, the water transparency is globally low and exceptionally exceeds 1m. Water conductivity is higher near the lake bottom, reaching 408 μS cm-1. The strong deficiency in oxygen contents recorded from 2.5m depth leads to the production of high quantities of ammonium nitrogen. The total phosphorus concentrations vary from 80 to 1650 μgP l-1, and the total Kjeldhal nitrogen concentrations fluctuate between 3 and 15 mgNH4 + l-1.  Upstream, the Mingoa exhibits total phosphorus concentrations ranging from 600 to 3800 μgP l-1, and total Kjeldhal nitrogen concentrations ranging from 10 to 22 mgNH4 + l-1. Conditions prevailing in this biotope favour a massive growth of phytoplankton, dominated by Euglenophyta and Chlorophyta. Both spatio-temporal analysis of phosphorus, chlorophyll a, and the composition of the  phytoplanktonic community, stress the anthropogenic impact on the ecosystem. The progression of this hydrosystem towards a dystrophic state is going on, and implies an urgent need for its restoration, followed by a rehabilitation of the “Grand Messa” sewage treatment plant, and the elimination process of solid materials in the tributary, upstream. Key words: sewage, lake, phytoplankton, eutrophication, central Africa

Les crustacés aquatiques souterrains d’Afrique et de Madagascar : bilan et enjeux

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Sorption Kinetics of Escherichia coli and Salmonella sp on Two Soil Layers Associated with a Groundwater Table in Yaounde, Cameroon (Central Africa)

A laboratory study has been carried out on two soil layers (HX and HY) located above a groundwater table in Yaounde, Cameroon (Central Africa). The main purpose of this study was to assess the retention potential or sorption kinetics of Escherichia coli and Salmonella sp. on these soil layers. For both soil layers, bacterial sorption on soil particles occurred rapidly during the first 30 minutes of incubation of bacteria and soil particles in aqueous media, and increased gradually with incubation time up to 300 min. In some cases, adsorption rates fluctuated after 30 min of incubation, probably due to bacterial cell sorption to and de-sorption from soil particles. Using Freundlich isotherms, it was noted that adsorption coefficient related to adsorption capacity varied from 19 to 4026 E. coli.mg-1 of soil, and from 506 to 847 Salmonella sp.mg-1 of soil. For both bacterial species, the adsorption coefficient of layer HY (located in close proximity of the water table) was greater than that of HX (located above layer HY) and seemed to positively correlate with the pH values and N/P ratios, and to negatively correlate with the values of C/N and C/P ratios. The linearity coefficient related to adsorption intensity varied from 0.5841 to 1.0023 for E. coli, and from 0.7068 to 1.5236 for Salmonella sp. The physico-chemical characteristics of soil particles seemed to influence the sorption kinetics of bacteria on soil

Lacs Monoun et Nyos au Cameroun: quand la nature, la science et les pensées autochtones africaines se confrontent!

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Isolement et mise en évidence des oocystes de Cyclospora cayetanensis dans un hydrosystème polysaprobe en zone équatoriale, Afrique Centrale

Peu de données sont disponibles sur la distribution des Apicomplexa parasites du tube digestif de l’homme. Ils causent pourtant des maladies diarrhéiques de très grande envergure. Une étude menée de janvier à août 2011, dans le cours d’eau Olézoa à Yaoundé (Cameroun), a visé à rechercher et caractériser les oocystes de Cyclospora cayetanensis. Les échantillonnages ont été effectués en amont et en aval du cours d’eau, sur deux stations localisées en zone fortement anthropisées. L’identification des oocystes de C. cayetanensis isolés à l’aide de l’observation directe après coloration au Lugol et selon la technique de Ziehl-Neelsen, a montré qu’ils sont constitués de deux sporocystes contenant chacun deux sporozoïtes. La dynamique d’abondance de ce microorganisme est significativement corrélée à la turbidité, à la température et au pH de l’eau (p < 0,01). Par ailleurs, les formes non sporulées sont plus abondantes que les formes sporulées dans l’environnement et sont fortement corrélées aux teneurs en oxygène dissous qui est un paramètre très important pour leur sporogénèse. En amont du cours d’eau, l’abondance la plus élevée de C. cayetanensis a été de 407 oocystes•L-1 et la valeur enregistrées en aval été de 250 oocystes•L-1. La population de C. cayetanensis observée a été largement dominée par les formes non sporulées de taille 8 µm. La concentration des oocystes la plus élevée en utilisant la technique directe et celle de Ziehl-Neelsen a été enregistrée respectivement au cours des mois de juin et juillet; ces périodes se situent respectivement à la fin de la petite saison des pluies et au début de la saison sèche.Little information is available on the distribution of enteropathogenic apicomplexa of the human digestive apparatus, these agents being responsible for endemic diarrheic diseases. A study carried out in the Olézoa water course in Yaoundé (Cameroon) revealed that this water contains the oocysts of Cyclospora cayetanensis. Samples for the analysis of biological and physico-chemical characteristics were obtained upstream and downstream with respect to the strongly human polluted zone. The identification of Cyclospora cayetanensis oocysts by direct observation and Ziehl-Neelsen techniques revealed that these oocysts contain two sporocysts, each having two sporozoïtes. Statistically, turbidity, temperature and pH have a significant effect (p<0.01) on the population dynamics of these microorganisms. The highest mean concentration of oocysts identified upstream was 407 oocysts•L-1 in the month of August. The non sporulated forms of oocysts are more abundant than the sporulated forms in the environment and are strongly linked to dissolved oxygen levels, oxygen being a parameter that is very important for the process of sporulation and viability. Non sporulated forms of oocysts, 8 µm in size, are dominant in the ecosystem analyzed in our investigations. These resistant forms of parasites that are present in the surface and wastewater represent a considerable health risk to the inhabitants of the study zone who could easily be exposed to cyclosporiasis.The two methods which have been carried out are complementary in the characterisation of the resistant forms of these enteropathogens

Adhesion of Candida albicans to polythene in Sodium hypochlorite disinfected aquatic microcosm and potential impact of cell surface properties

International audienceThe adhesion of C. albicans cells harvested from different growth stages to polythene in Sodium hypochlorite (NaOCl) treated water, under static and dynamic conditions was carried out. With cells harvested from the lag, exponential, stationary and decline growth phases, the highest abundance of cells adhered was respectively 0.75, 1.18, 0.85 and 0.95 units (Log (CFU/cm²)), when considering the static and dynamic experimental condition. The hydrophobicity values ranged respectively from 17 to 99, 45 to 93, 8 to 93, and from 10 to 83 %. The increase in incubation duration was significantly correlated (P<0.01) to the decrease in the abundance of adhered C. albicans when considering the NaOCl concentrations used. The increase in the NaOCl concentration in water was significantly correlated (P<0.01) to the increase in the abundance C. albicans adhered to polythene when considering the incubation durations. An increase in NaOCl concentration in the water seems significantly correlated with the decrease of the abundance of C. albicans adhered to the substrate (P<0.01) when considering each cell growth phase. Using the H (Kruskal-Wallis) test to compare the registered mean abundances of cells adhered to polythene after living in water treated with various concentrations of NaOCl with respect to the growth phase, a significant difference (P<0.05) was noted with cells coming from the exponential, stationary and decline growth stages. The adhesion of C. albicans to polythene seems to be impacted by various factors with some depending on the cells status

Morphology and infraciliature of two new earthworm ciliates, Hoplitophrya polymorphus sp. nov. and Anoplophrya simplex sp. nov. (Ciliophora: Oligohymenophorea: Astomatia)

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