Isolation, screening and identification of ethanol producing yeasts from Ethiopian fermented beverages.

The growing demand for renewable energy sources such as bioethanol is facing a lack of efficient ethanologenic microbes. This study aimed to isolate and screen ethanologenic yeasts from Ethiopian fermented beverages. A progressive screening and selection approach was employed. Selected isolates were evaluated for bioethanol production using banana peel waste as substrate. A total of 102 isolates were obtained. Sixteen isolates were selected based on their tolerance to stress conditions and carbohydrate fermentation and assimilation capacity. Most found moderately tolerant to 10 %, but slightly tolerant at 15 and 20 % (v/v) ethanol concentration. They yield 15.3 to 20.1 g/L and 9.1 ± 0.6 to 12.9 ± 1.3 g/L ethanol from 2 % (w/v) glucose and 80 g/L banana peel, respectively. Molecular characterization identified them as Saccharomyces cerevisiae strains. Results demonstrate insight about their potential role in the ethanol industry. Optimization of the fermentation conditions is recommended.

Microbial diversity, transformation and toxicity of azo dye biodegradation using thermo-alkaliphilic microbial consortia.

In this research, the transformation and toxicity of Reactive Red 141 and 239 biodegraded under anaerobic-aerobic conditions as well as metagenomic analysis of Reactive Red 239 degrading microbial consortia collected from Shala Hot spring were investigated. Toxicity of dyes before treatment and after treatment on three plants, fish and microorganisms were done. A halotolerant and thermo-alkaliphilic bacterial consortia decolorizing azo dyes (>98% RR 141 and > 96% RR 239 in 7 h) under optimum conditions of salt concentration (0.5%), temperature (55 °C) and pH (9), were used. Toxicity effect of untreated dyes and treated dyes in Tomato > Beetroot > Cabbage plants, while the effect was Leuconostoc mesenteroides > Lactobacillus plantarum > Escherichia coli in microorganisms. Among fishes, the toxicity effect was highest in Oreochromis niloticus followed by Cyprinus carpio and Clarias gariepinus. The three most dominant phyla that could be in charge of decolorizing RR 239 under anaerobic-aerobic systems were Bacteroidota (22.6-29.0%), Proteobacteria (13.5-29.0%), and Chloroflexi (8.8-23.5%). At class level microbial community structure determination, Bacteroidia (18.9-27.2%), Gammaproteobacteria (11.0-15.8%), Alphaproteobacteria (2.5-5.0%) and Anaerolineae (17.0-21.9%) were dominant classes. The transformation of RR 141 and RR 239 into amine compounds were proposed via high performance liquid chromatography-mass spectroscopy (HPLC/MS) and fourier transform infrared spectroscopy (FT-IR). Overall, dye containing wastewaters treated under anaerobic-aerobic systems using thermo-alkaliphilic microbial consortia were found to be safe to agricultural (fishes and vegetables) purposes.

Evaluating the potential of thermo-alkaliphilic microbial consortia for azo dye biodegradation under anaerobic-aerobic conditions: Optimization and microbial diversity analysis.

Wastewaters in textile industry are mainly characterized by higher pH, color, salt and chemical oxygen demand (COD) values, which are environmentally undesirable. Among these textile effluent characteristics, color removal is the most challenging task. In this study, the potential of Rift Valley halotolerant and thermo-alkaliphilic microbial consortia (collected from Shala hot spring located in Ethiopia) for azo dye biodegradation under anaerobic-aerobic conditions were evaluated. Optimization and microbial diversity analysis were done using Reactive Red 141. Under optimum conditions of pH (9), temperature (55 °C), salinity (0.5%), and nutrients, microbial consortia can remove >98% color and 92.7 ± 7.3% COD under anaerobic and aerobic conditions, respectively. In addition, the consortia was capable of decolorizing initial dye concentrations of 100-1000 mg/L, and various dye types including Everzol Blue LX, RY 84, RR 239, RB 198 and RY 700. The 16S rRNA gene sequence results showed that Bacteroidetes (25.3%) > Proteobacteria (21.0%) > Chloroflexi (18.5%) > Halobacterota (6.2%) dominant phyla. Based on the findings, non-color effluent adapted Rift Valley halotolerant and thermo-alkaliphilic bacterial consortia can be a potential candidate for bioremediation of textile and other industries characterized by higher salinity, temperature and pH.

Microbial community shifts association with physicochemical parameters: Visualizing enset bacterial wilt from different states of enset health.

Bacterial wilt of enset caused by Xanthomonas campestris is a devastating disease in Ethiopia, where enset is domesticated and served as a staple food for about 20 million people in the country. While enset is infected by bacteria, it shows different wilting stages. However, the microbial community shifts at the different stages of enset infection and associated physicochemical parameter changes remain poorly understood. This study was aimed to visualize the proportion of enset wilt bacterium from other microbial community and its association with physicochemical parameter at different states of enset health. Soil and enset (zero, first, second and third stages) samples were collected from three districts in Gamo Highlands for physicochemical and biological (culture dependent and16S rRNA gene sequence) analysis. The results of culture dependent analysis which has been complemented by 16S rRNA gene sequence confirmed that increasing trends were observed for Xanthomonadaceae, Pseudomonadaceae, Lactobacillaceae and Flavobacteriaceae, while Bacillaceae and Enterobacteriaceae showed progressive decrease from zero to the third stage. Particularly, the 16S rRNA data showed that Xanthomonadaceae increased significantly from zero to different (2.5 × 102 times at the onset of disease and 1.0-2.0 × 104 times at the second and third) stages of enset infection. Most physicochemical results showed that a decreasing trends from zero to third stage, while few parameters are showing an increasing trend. Moisture content (R2 ≥ 0.951, P ≤ 0.049) of the soil and plant samples positively influenced Xanthomonas abundance, while this bacterium showed a strongly negative significant correlation with pH (R2 ≥ -0.962, P ≤ 0.038), temperature (R2 ≥ -0.958, P ≤ 0.042), OM (R2 ≥ -0.952, P ≤ 0.048), and TN (R2 ≥ -0.951, P ≤ 0.049). A strongly negative significant correlation (R2 ≥ -0.948, P ≤ 0.050) was also observed between Xanthomonas and nutrients (K, Mg, Ca, and Cu). Overall, this study implies that different environmental factors found a key driving force of Xanthomonas proportional increment from low abundance at zero stage to higher abundance at the last stage of enset infection suggesting that considering these factors help to design an effective enset disease management strategy, for which further studies will be needed.

The role of spices and lactic acid bacteria as antimicrobial agent to extend the shelf life of metata ayib (traditional Ethiopian spiced fermented cottage cheese).

Spices and lactic acid bacteria have natural antimicrobial substances and organic compounds having antagonistic activity against microorganisms. The objective of this study was to investigate the role of spices and lactic acid bacteria as antimicrobial agent to extend the shelf life of metata ayib. Antimicrobial activities of spices and lactic acid bacteria (LAB) filtrates were determined by agar well diffusion method against E. coli, S. aureus, S. flexneri and S. peumoniae. Aantimicrobial activity of garlic was found to be the most effective against all the tested pathogens. Inhibition zones of garlic extract against all pathogens was significantly (P ≤ 0.05) greater than the remaining spice extracts. Inhibition zones (12.50 ± 1.00 to 15.50 ± 1.00 mm) of ginger and R. graveolens ethanol extracts against all tested pathogens were significantly (P ≤ 0.05) greater than the remaining solvent extracts. Inhibition zone of O. basilicum ethanol extract against all pathogenic bacteria was significantly (p ≤ 0.05) greater than hexane and acetone extracts. Lactobacillus isolates were shown the highest antimicrobial activity than the other LAB isolates against all pathogens. The synergistic effect of spices together with LAB might be contributed a lot to preserve and extend shelf life of metata ayib. Their antimicrobial activity can reduce the risk of spoilage and pathogenesis. The possible reason of LAB isolates was may be due to production of lactic acid, acetic acid and secondary metabolites like bacteriocins. Aseptic processing of traditional cottage cheese (ayib) is by far needed to minimize risks associated during consumption of metata ayib.

Proximate composition, mineral content and antinutritional factors of Brebra (Millettia ferruginea) seed flour as well as physicochemical characterization of its seed oil.

Still there is no scientific report about the proximate analysis of seeds and characteristics of oil produced from brebra seed. Objective of this study was to determine proximate and antinutritional characteristics of seeds as well as the physicochemical characteristics of brebra seed oil. Crude oil, protein, fiber, ash, moisture and carbohydrate content of brebra were 48.5 ± 0.99%, 29.7 ± 0.23%, 2.41 ± 0.12%, 3.24 ± 0%, 4.24 ± 0.04% and11.92 ± 0.2%, respectively. Seed has concentrated energy (6.0298 Kcal/gm). The respective tannin, oxalate and phytic acid value were 84.3 ± 0.89 mg/100 gm, 20.97 ± 0.36 mg/100 gm and 291.62 ± 0.87 mg/100 gm, respectively. Cyanide was not detected in the sample. Seed contains high concentration of phosphorus (1062.1 ± 0.3 mg/100 g), potassium (281 ± 0.1 mg/100 g), magnesium (112.38 ± 0.1 mg/g), sodium (93.26 ± 0.1 mg/g) and calcium (61.55 ± 0.01 mg/g). The oil was analyzed for specific gravity at 20°C, viscosity at 40°C, refractive index at 40°C, acid value, saponification value, iodine value, peroxide value and ester value. Their respective values were 0.942, 40.59 mm(2)/s, 1.473, 0.39 mg KOH/g, 174.95 mg KOH/g, 104.48 gI2/100 g, 6.88 and 174.56 mg KOH/g. Unsaturated fatty acids accounts (80.7%), of which 48.2% and 27.7% were linolcic and linolenic, respectively, which make suitable for production of biodiesel. Seed has higher nutrient composition, low antinutritional elements and high calorie value compared to some legumes.

Production of microbial medium from defatted brebra (Milletia ferruginea) seed flour to substitute commercial peptone agar.

OBJECTIVE: To investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour. METHODS: Defatted process, inoculums preparation, evaluation of bacterial growth, preparation of cooked and hydrolyzed media and growth turbidity of tested bacteria were determined. RESULTS: Two percent defatted flour was found to be suitable concentration for the growth of pathogenic bacteria: Escherichia coli (ATCC 25922) (E. coli), Pseudomonas aeruginosa (ATCC 27853), Salmonella (NCTC 8385) and Shigella flexneri (ATCC 12022) (S. flexneri), while 3% defatted flour was suitable for Staphylococcus aureus (ATCC 25923) (S. aureus). E. coli (93±1) and S. flexneri (524±1) colony count were significantly (P≤0.05) greater in defatted flour without supplement than in supplemented medium. E. coli [(3.72×10(9)±2) CFU/mL], S. aureus [(7.4×10(9)±2) CFU/mL], S. flexneri [(4.03×10(9)±2) CFU/mL] and Salmonella [(2.37×10(9)±1) CFU/mL] in non-hydrolyzed sample were statistically (P≤0.05) greater than hydrolyzed one and commercial peptone agar. Colony count of Salmonella [(4.55×10(9)±3) CFU/mL], S. flexneri [(5.40×10(9)±3) CFU/mL] and Lyesria moncytogenes (ATCC 19116) [(5.4×10(9)±3) CFU/mL] on raw defatted flour agar was significantly (P≤0.05) greater than cooked defatted flour and commercial peptone agar. Biomass of E. coli, S. aureus, Salmonella and Enterococcus faecalis in non-hydrolyzed defatted flour is highly increased over hydrolyzed defatted flour and commercial peptone broth. CONCLUSIONS: The defatted flour agar was found to be better microbial media or comparable with peptone agar. The substances in it can serve as sources of carbon, nitrogen, vitamins and minerals that are essential to support the growth of microorganisms without any supplements. Currently, all supplements of peptone agar are very expensive in the market.

Combined antibacterial activity of stingless bee (Apis mellipodae) honey and garlic (Allium sativum) extracts against standard and clinical pathogenic bacteria.

OBJECTIVE: To investigate the synergic antibacterial activity of garlic and tazma honey against standard and clinical pathogenic bacteria. METHODS: Antimicrobial activity of tazma honey, garlic and mixture of them against pathogenic bacteria were determined. Chloramphenicol and water were used as positive and negative controls, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration of antimicrobial samples were determined using standard methods. RESULTS: Inhibition zone of mixture of garlic and tazma honey against all tested pathogens was significantly (P≤0.05) greater than garlic and tazma honey alone. The diameter zone of inhibition ranged from (18±1) to (35±1) mm for mixture of garlic and tazma honey, (12±1) to (20±1) mm for tazma honey and (14±1) to (22±1) mm for garlic as compared with (10±1) to (30±1) mm for chloramphenicol. The combination of garlic and tazma honey (30-35 mm) was more significantly (P≤0.05) effective against Salmonella (NCTC 8385), Staphylococcus aureus (ATCC 25923), Lyesria moncytogenes (ATCC 19116) and Streptococcus pneumonia (ATCC 63). Results also showed considerable antimicrobial activity of garlic and tazma honey. MIC of mixture of garlic and tazma honey at 6.25% against total test bacteria was 88.9%. MIC of mixture of garlic and tazma honey at 6.25% against Gram positive and negative were 100% and 83.33%, respectively. The bactericidal activities of garlic, tazma honey, and mixture of garlic and tazma honey against all pathogenic bacteria at 6.25% concentration were 66.6%, 55.6% and 55.6%, respectively. CONCLUSIONS: This finding strongly supports the claim of the local community to use the combination of tazma honey and garlic for the treatment of different pathogenic bacterial infections. Therefore, garlic in combination with tazma honey can serve as an alternative natural antimicrobial drug for the treatment of pathogenic bacterial infections. Further in vivo study is recommended to come up with a comprehensive conclusion.

Diarrhoea-associated parasites in HIV-1 seropositive and sero-negative patients in a teaching hospital, Northwest Ethiopia.

OBJECTIVE: to determine the prevalence and type of intestinal parasites in HIV infected and uninfected patients with diarrhea. DESIGN: A cross-sectional study was conducted at Gondar University hospital, Northwest Ethiopia, between March 2003 and October 2004. PATIENTS AND METHODS: A total 312 consecutive diarrheic patients were included in the study. Stool specimens were collected and examined for intestinal parasites following direct, formol-ether concentration and modified acid fast staining methods. RESULTS: Among the patients, 63.8% were found to be HIV seropositive. The prevalence of intestinal parasites in HIV seropositive and seronegative diarrheic patients was 30.6% and 33.6%, respectively. The most prevalent parasites were Strongyoides stercoralis (9.0%) and Entamoeba histolytica (8.3%) followed by Ascaris lumbricoides (5.4%) and Cryptosporidium species (5. 1%). CONCLUSION AND RECOMMENDATION: The prevalence of intestinal parasites in diarrheic patients was very high. Institution of appropriate intervention measures are needed to reduce morbidity in such patients.

Vitamin A deficiency in patients with diarrhea and HIV infection in Ethiopia.

Diarrhea, micronutrient deficiencies and HIV/AIDS are major public health problems in developing countries, especially in sub-Saharan Africa. This study was aimed to investigate serum levels of vitamin A in diarrheic patients with and without HIV co-infection compared to healthy controls. Two hundred eleven diarrheic patients (110 HIV infected), 87 apparently healthy controls and 41 asymptomatic HIV seropositive blood donors who visited the University of Gondar Hospital, in Gondar, Ethiopia were included. Stool samples were examined for enteropathogens following the standard procedures. Serum vitamin A levels were measured by high performance liquid chromatography. Shigella species were isolated from 8.5% of the patients while intestinal parasites were detected in 32.2% without significant difference by HIV serostatus. The mean+/-SD serum vitamin A in diarrheic patients with (0.82+/-0.59 micromol/L) and without (0.84+/-0.54 micromol/L) HIV co-infection and in asymptomatic HIV infected blood donors (0.96+/-0.52 micromol/L) was significantly lower than that in healthy controls (1.52+/-0.71 micromol/L), p<0.001. Vitamin A deficiency (VAD, serum retinol < 0.70 micromol/L) was observed in 52.7% and 45.5% of diarrheic patients with and without HIV co-infection, respectively. About 13% of healthy controls and 29.3% of asymptomatic HIV infected blood donors were deficient in vitamin A. The levels of serum vitamin A were not associated with the presence of intestinal parasites or Shigella species. The findings demonstrate that VAD is a severe public health problem among diarrheic patients in Gondar, Ethiopia. Intervention programmes involving health and nutrition education and supplementation of vitamin A might help in reducing morbidity in such patients.

Seroprevalence of Helicobacter pylori in dyspeptic patients and its relationship with HIV infection, ABO blood groups and life style in a university hospital, Northwest Ethiopia.

AIM: To determine the prevalence of Helicobacter pylori (H pylori) among dyspeptic patients and to assess the relationship between H pylori infection, blood group, HIV infection and life style of the patients. METHODS: In a hospital-based cross-sectional study, patients attending Outpatient Department of University of Gondar Hospital were enrolled. Socio-demographic information was collected using questionnaires. Serum was analyzed for anti-H pylori IgG antibodies using a commercial kit. HIV serostatus was determined by enzyme-linked immunosorbent assay (ELISA). Blood grouping was performed by slide agglutination tests. RESULTS: A total of 215 dyspeptic patients were included in the study. One hundred and sixteen patients (54%) were females and 99 (46%) were males. Anti-H pylori IgG antibodies were detected in sera of 184 (85.6%) patients. The prevalence was significantly higher in patients aged 50 years and above. Twenty point five percent of the patients were found to be seropositive for HIV. No significant association was found between sex, ABO blood groups, consumption of spicy diets, socio-economic status and seropositivity for H pylori. However, alcohol consumption was significantly associated with H pylori serology. CONCLUSION: The prevalence of H pylori infection is associated with a history of alcohol intake and older age. The effect of different diet, alcohol and socioeconomic status as risk factors for H pylori infection needs further study.