Effect of curd-cooking temperatures on the microbiological quality ofayib,a traditional Ethiopian cottage cheese

Ayib was made following traditional methods of curd cooking at 40°, 50°, 60° and 70°C requiring 10 h, 7 h, 145 min and 55 min, respectively. During the natural fermentation of raw milk into sour milk (curd), the count of all groups of microorganisms increased by at least a 100-fold. When the curd was subsequently cooked at 40°C, counts of enterococci and members of Enterobacteriaceae decreased by a 100-fold and lactic acid bacteria and staphylococci by a 100-fold. At 50°C, the count of enterococci, members of Enterobacterlaceae and staphylococci was lower than could be detected (<10² c.f.u./g). Yeasts, moulds and lactic acid bacteria still had counts of about 10⁵ c.f.u./g. The total aerobic count decreased by a 100-fold but was still high (>10⁷ c.f.u./g). At 60°C, yeasts and moulds decreased by 1000-fold and at 70°C they decreased below detectable levels (<10² c.f.u./g). This latter temperature is thus recommended as it results in a less contaminated and saferayib.

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Résumé On a préparél'Ayib selon les méthodes traditionnelies de cuission du lait caillé à 40, 50, 60 et 70°C, ce qui a requis respectivement 10 h, 7 h, 145 et 55 min. Durant la fermentation naturelle du lait frais en lait caillé, le décompte de tous les groupes de microorganismes a crû d'au moins 100 fois. Quand le lait caillé était par la suite cuit à 40°C, le décompte des entérocoques et des membres des Enterobacteriaceae a décru de 100 fois et celui des bactéries lactiques et des staphylocoques de 100 fois. A 50°C, le décompte des entérocoques, membres des Enterobacteriaceae et des staphylocoques était inférieur au seuil de détection (<10² c.f.u./g). Les levures, moisissures et bactéries lactiques avalent toujours un décompte d'environ 10⁵ c.f.u./g. le décompte total aérobie décroissait de 100 fois mais restait néanmoins élevé (>10⁷ c.f.u./g.). A la température de cuisson du lait caillé de 60°C, les levures et les moisissures ont décru de 1000 fois, et à 70°C on décru au dessous du seuil de détection (<10² c.f.u./g). Cette dernière température est donc recommandable car elle résulte en unayib moins contaminé et plus sain.

     

Growth of Bacillus cereus in fermenting tempeh made from various beans and its inhibition by Lactobacillus plantarum

Counts of Bacillus cereus reached ca 10(8) cfu/g within 40 h in fermenting unacidified horsebean tempeh and resulted in complete spoilage of the product. In fermenting unacidified pea, chickpea and soybean tempeh, B. cereus counts reached 10(6)-10(7) cfu/g, although the products were not spoiled. Inoculation of these unacidified beans with Lactobacillus plantarum decreased the final count of B. cereus by 2 log units, but had no effect on its growth in unacidified horsebean tempeh and its subsequent spoilage. Acidification of the beans during soaking resulted in a lower rate of B. cereus growth during fermentation. Inoculation of acidified beans with Lact. plantarum resulted in a markedly lower growth rate of B. cereus. In an associative broth culture study, B. cereus was completely inhibited by Lact. plantarum at pH values of about 5.5. Lactobacillus plantarum may be used to control the growth of B. cereus during tempeh production.     

Screening for Tannin Degradation by Rumen and Faecal Samples of Wild and Domestic Animals in Ethiopia

Summary Tannins limit the use of fodder trees as feed for ruminants. Removal of the effects of tannins would thus improve the nutritional quality of these trees. This prompted the study to evaluate the effect of rumen or faecal mixed cultures from different animals on tannin degradation. Tannin extracts, tannic acid and gallic acid were used to enrich media to assess if rumen or faecal mixed cultures could degrade the phenolic compounds. Rumen fluid of Acacia-adapted sheep, sheep fed on wheat bran, bush duikers (Sylvicapra grimmia) and goats fed on Leucaena pallida and Sesbania goetzei were separately inoculated into Growth Study Medium (GSM) and incubated for 5-15 days. Faecal samples from dikdik (Madoqua guentheri), camel (Camelus dromedarius), zebra (Equus quagga), Grant’s gazelle (Gazella granti) and hartebeest (Alcelaphus buselaphus) were also separately inoculated into GSM media and incubated from 3-5 days. TLC results showed that mixed cultures from rumen fluids of Acacia-adapted sheep, sheep on wheat bran, goats on Leucaena pallida and Sesbania goetzei partially hydrolysed tannic acid to pyrogallol. Complete degradation of the heterocyclic ring in tannic acid and gallic acid was achieved by the mixed cultures from the faecal samples of dikdik and this was confirmed by HPLC. Mixed cultures from faecal samples of camel hydrolysed gallic acid to phloroglucinol. This study has demonstrated that faecal microorganisms of Ethiopian dikdik could completely degrade hydrolysable tannin.     

The prion protein binds thiamine

Although highly conserved throughout evolution, the exact biological function of the prion protein is still unclear. In an effort to identify the potential biological functions of the prion protein we conducted a small-molecule screening assay using the Syrian hamster prion protein [shPrP(90-232)]. The screen was performed using a library of 149 water-soluble metabolites that are known to pass through the blood-brain barrier. Using a combination of 1D NMR, fluorescence quenching and surface plasmon resonance we identified thiamine (vitamin B1) as a specific prion ligand with a binding constant of ~60 μM. Subsequent studies showed that this interaction is evolutionarily conserved, with similar binding constants being seen for mouse, hamster and human prions. Various protein construct lengths, both with and without the unstructured N-terminal region in the presence and absence of copper, were examined. This indicates that the N-terminus has no influence on the protein's ability to interact with thiamine. In addition to thiamine, the more biologically abundant forms of vitamin B1 (thiamine monophosphate and thiamine diphosphate) were also found to bind the prion protein with similar affinity. Heteronuclear NMR experiments were used to determine thiamine's interaction site, which is located between helix 1 and the preceding loop. These data, in conjunction with computer-aided docking and molecular dynamics, were used to model the thiamine-binding pharmacophore and a comparison with other thiamine binding proteins was performed to reveal the common features of interaction.     

Chronic exposure to staphylococcal superantigen elicits a systemic inflammatory disease mimicking lupus

Chronic nasal and skin colonization with superantigen (SAg)-producing Staphylococcus aureus is well documented in humans. Given that trans-mucosal and trans-cutaneous absorption of SAgs can occur, we determined whether chronic exposure to small amounts of SAg per se could activate autoreactive CD4(+) and CD8(+) T cells and precipitate any autoimmune disease without further external autoantigenic stimulation. Because HLA class II molecules present SAg more efficiently than do mouse MHC class II molecules, HLA-DQ8 transgenic mice were implanted s.c. with mini-osmotic pumps capable of continuously delivering the SAg, staphylococcal enterotoxin B (total of 10 μg/mouse), or PBS over 4 wk. Chronic exposure to staphylococcal enterotoxin B resulted in a multisystem autoimmune inflammatory disease with features similar to systemic lupus erythematosus. The disease was characterized by mononuclear cell infiltration of lungs, liver, and kidneys, accompanied by the production of anti-nuclear Abs and deposition of immune complexes in the renal glomeruli. The inflammatory infiltrates in various organs predominantly consisted of CD4(+) T cells bearing TCR Vβ8. The extent of immunopathology was markedly reduced in mice lacking CD4(+) T cells and CD28, indicating that the disease is CD4(+) T cell mediated and CD28 dependent. The absence of disease in STAT4-deficient, as well as IFN-γ-deficient, HLA-DQ8 mice suggested the pathogenic role of Th1-type cytokines, IL-12 and IFN-γ. In conclusion, our study suggests that chronic exposure to extremely small amounts of bacterial SAg could be an etiological factor for systemic lupus erythematosus.     

Yeheb (<Emphasis Type="Italic">Cordeauxia</Emphasis><Emphasis Type="Italic">edulis</Emphasis>) extract deters feeding and oviposition of <Emphasis Type="Italic">Plutella xylostella</Emphasis> and attracts its natural enemy

The effects of yeheb (Cordeauxia edulis Hemsl.) leaf extract on feeding and oviposition by diamondback moth (DBM) (Plutella xylostella L.) and the behavior of DBM parasitoid, Cotesia vestalis (Haliday), were studied. Volatile organic compounds (VOCs) from the headspace of intact and DBM-damaged broccoli plants sprayed with yeheb extracts (YE) were also analyzed. Larval feeding and growth, and oviposition by adult DBM were strongly inhibited by the extract. Cotesia vestalis were attracted to volatile blends from intact or DBM-damaged broccoli plants sprayed with YE over intact plants sprayed with water or methanol. Analyses of VOCs in the headspace of broccoli plants revealed that both intact and DBM-damaged plants sprayed with YE showed remarkable differences in sesquiterpene compounds compared to intact control treatments. These combined negative effects of YE on DBM fitness together with positive effects on the parasitoid show that yeheb is a potential source of compounds for use in integrated pest management to control damage caused by DBM.     

The impact of asymptomatic helminth co-infection in patients with newly diagnosed tuberculosis in north-west ethiopia

Background

Areas endemic of helminth infection, tuberculosis (TB) and HIV are to a large extent overlapping. The aim of this study was to assess the impact of asymptomatic helminth infection on the immunological response among TB patients with and without HIV, their house hold contacts and community controls.

Methodology

Consecutive smear positive TB patients (n = 112), their household contacts (n = 71) and community controls (n = 112) were recruited in Gondar town, Ethiopia. Stool microscopy, HIV serology, serum IgE level, eosinophil and CD4 counts were performed and tuberculosis patients were followed up for 3 months after initiation of anti-TB treatment.

Results

Helminth co-infection rate was 29% in TB patients and 21% in both community control and household contacts (p = 0.3) where Ascaris lumbricoides was the most prevalent parasite. In TB patients the seroprevalence of HIV was 47% (53/112). Eosinophilia and elevated IgE level were significantly associated with asymptomatic helminth infection. During TB treatment, the worm infection rate of HIV+/TB patients declined from 31% (10/32) at week 0 to 9% (3/32) at week 2 of TB treatment, whereas HIV−/TB patients showed no change from baseline to week 2, 29% (13/45) vs. 22.2% (10/45). This trend was stable at week 8 and 12 as well.

Conclusion

One third of smear positive TB patients were infected with helminths. Eosinophilia and elevated IgE level correlated with asymptomatic worm infection, indicating an effect on host immunity. The rate of worm infection declined during TB treatment in HIV+/TB co-infected patients whereas no decline was seen in HIV−/TB group.     

Microbial load,incidence and antibiotic resistance of some disease-causing microorganisms on raw food items in consumed Ethiopia

Summary A total of 708 strains belonging to different bacterial genera were isolated from fresh tomatoes, eggs, green peppers and fish sold in open markets in Awassa, Ethiopia. They mainly consisted of coliforms (54%),Staphylococcus aureus (26%) andProteus (16%).Shigella was isolated from 26% of the tomato specimens. Total counts for the various food items varied between 2.4 × 10⁶ c.f.u./g and 9.5 × 10⁶ c.f.u./g. Most probable number of total coliform and faecal coliform ranged from 1.5 × 10²/g to 3 × 10²/g and 37/g to 70/g. Less than 50% of the isolated 522 Gram-negative rods were susceptible to ampicillin and cephalothin and only 14 isolates were susceptible to all drugs tested.Proteus showed higher rates of resistance to ampicillin, carbenicillin and cephalothin (75%). Resistance to these drugs was also relatively higher inEscherichia coli (50%). Sixty-eight of the 186S. aureus isolates were sensitive to all the drugs tested and susceptibility to tetracycline and chloramphenicol was relatively lower (70%).

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Charge microbienne, incidence et résistance aux antibiotiques de quelques micro-organismes dans des aliments destinés à être consommés crus en Ethiopie

Résumé On a isolé un total de 708 souches appartenant à divers genres bactériens de tomates fraîches, d'oeufs, de poivrons verts et de poissons vendus sur les marchés ouverts en Awassa, Ethiopie. Parmi celles-ci, on a trouvé 26% deStaphylococcus aureus et 16% deProteus. On a isolé desShigella dans 26% des tomates testées. L'énumération totale des germes dans divers aliments a donné des valeurs situées entre 2.4 × 10⁶ c.f.u./g et 9.5 × 10⁶ c.f.u./g. Le nombre le plus probable de coliformes totaux et de coliformes fécaux variait entre 1.5 × 10²/g et 3 × 10²/g et entre 37/g et 70/g. Moins de 50% des 522 souches isolées à forme de bâtonnets étaient sensibles à l'ampicilline et à la céphalothine et seules 14 souches isolées étaient sensibles à toutes les drogues testées. LesProteus ont montré davantage de résistance à l'ampicilline, la carbénicilline et la céphalothine (75%). La résistance à ces drogues était aussi relativement plus élevée chezEscherichia coli. Soixante huit de 186 souches isolées deS. aureus étaient sensibles à toutes les drogues testées et leur sensibilité à la tétracycline et au chloramphenicol était relativement plus faible (70%).

     

Sero-prevalence,risk factors and distribution of sheep and goat pox in Amhara Region,Ethiopia

Background

Sheep pox and goat pox are contagious viral diseases of sheep and goats, respectively. The diseases result in substantial economic losses due to decreased milk and meat production, damage to hides and wool, and possible trade restriction. A study was undertaken in Amhara region of Ethiopia. A cross-sectional study design was used to estimate the sero-prevalence and identify associated risk factors, while retrospective study design was used to assess the temporal and spatial distribution of the disease. A total of 672 serum samples were collected from 30 Kebeles and tested using virus neutralization test.

Results

From a total of 672 sera tested, 104 (15.5%) were positive for sheep and goat pox virus antibody; from which 56 (17%) were sheep and 48 (14%) were goats. The diseases were prevalent in all study zones, the highest sero-prevalence was observed in South Gondar (20.9%) and the lowest in North Gondar and West Gojjam zones (11.9% each). From the potential risk factors considered (species, sex, age, agro-ecology and location); only sex and age were significantly associated (p?<?0.05) with the diseases in multivariable logistic regression. Female and young animals were at higher risk than their counterparts. From January 2010 to December 2014, a total of 366 outbreaks, 12,822 cases and 1480 deaths due to SP and 182 outbreaks, 10,066 cases and 997 deaths due to GP were recorded in Amhara National Regional State.

Conclusion

Both the serological and the outbreak data revealed that sheep and goat pox is one of the most prevalent and widespread diseases of sheep and goats in the study area. Hence, annual mass vaccination program must be implemented for economic and viable control of sheep and goat pox diseases in the Amhara region in particular and at a national level in general.