Haricot bean (Phaseolus vulgaris L.) is one of the most important cash crops and export commodities besides its use in human food and soil fertility improvement. Phosphorus (P) is one of the major bio-elements that limits agricultural... more
Haricot bean (Phaseolus vulgaris L.) is one of the most important cash crops and export commodities besides its use in human food and soil fertility improvement. Phosphorus (P) is one of the major bio-elements that limits agricultural production. However, phosphate-solubilizing fungi play a noteworthy role in increasing the bioavailability of soil phosphates for plants. The purpose of this study was to evaluate the effects phosphate solubilizing fungi on the growth of haricot bean plants. Cultural and morphological features were used to tentatively identify the fungal isolates to genus level. Based In vitro phosphate solubilization efficieny conducted in both solid and liquid PVK medium following standard procedures, two best isolates were selected and evaluated under greenhouse for their performance on haricot bean. Under greenhouse experiment, shoot height (47.31 cm plant-1), root length (41.01 cm plant-1), nodule number (65.67 plant-1), nodule dry weight (0.59 g plant-1), shoot f...
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Research Interests: Food Science, Biology, Ethanol Fuel, Sugar, Yeast, and 3 moreFermentation, Effluent, and Coffea arabica
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Tuta absoluta (tomato leafminer) is one of the devastating agricultural pest that attack mainly tomatoes. The continuous use of chemical pesticides is not affordable and poses a collateral damage to human and environmental health. This... more
Tuta absoluta (tomato leafminer) is one of the devastating agricultural pest that attack mainly tomatoes. The continuous use of chemical pesticides is not affordable and poses a collateral damage to human and environmental health. This requires integrated pest management to reduce chemical pesticides. B. thuringiensis is a cosmopolitan, antagonistic soil bacterium used to control agricultural pests. In this study, effective Bt strains were screened from different sample sources based on their lepidopteran specific cry genes and larvicidal efficacy against tomato leafminer, T. absoluta under laboratory conditions. Of the 182 bacterial isolates, 55 (30 %) of isolates harbored parasporal protein crystals. Out of these, 34 (62 %) isolates possess one or more lepidopteran specific cry genes: 20 % of isolates positive for cry2, 18.2 % for cry9, 3.6 % for cry1, 16.4 % for cry2 + cry9, 1.8 % for cry1 + cry9, and 1.8 % for cry1 + cry2 + cry9. However, 21 (38.2 %) isolates did not show any lepidopteran specific cry genes. Isolates positive for cry genes showed 36.7-75 % and 46.7-98.3 % mortality against second and third instar larvae of the T. absoluta at the concentration of 108 colony forming units (CFUs) ml-1. Cry1 and cry1 plus other cry gene positive isolates were relatively more pathogenic against T. absoluta. However, third instar larvae of the T. absoluta was more susceptible than second instar larvae. Two of the isolates, AAUF6 and AAUMF9 were effective and scored LT50 values of 2.3 and 2.7 days and LC50 values of 3.4 × 103 and 4.15 × 103 CFUs ml-1 against the third instar larvae, respectively. The phylogenetic studies showed some congruence of groups with cry gene profiles and lethality level of isolates and very interestingly, we have detected a putative new phylogenetic group of Bt from Ethiopia.
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Streptomyces sp. has provided a wealth of bioactive secondary metabolites with interesting antimicrobial, antiviral, and anticancer activities. This study aimed to optimize antibiotic production medium and growth conditions of... more
Streptomyces sp. has provided a wealth of bioactive secondary metabolites with interesting antimicrobial, antiviral, and anticancer activities. This study aimed to optimize antibiotic production medium and growth conditions of Streptomyces monomycini RVE129 isolated from rhizospher soil of Hawassa, Ethiopia, under shaking conditions by traditional and statistical methods. The classical one-factor-at-a-time (OFAT) approach and the statistical Plackett Burman (PB) design was used for the selection of the important media components; which were further optimized and identify their concentrations using Box-Behnken design for improved antibiotic production by Streptomyces monomycini RVE129. The antibacterial activity of obtained antibiotics by the strain in flask cultures was tested using the disc diffusion method with S. aureus as the test organism, and cell growth was measured as the weight of dry cells in a constant volume of culture broth. Streptomyces monomycini strain RVE129 was abl...
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The study was undertaken to isolate, screen, and identify actinomycetes with antimicrobial metabolites. Twenty-one composite soil samples were randomly collected from various unique agroecological niches in the Rift Valley of Ethiopia.... more
The study was undertaken to isolate, screen, and identify actinomycetes with antimicrobial metabolites. Twenty-one composite soil samples were randomly collected from various unique agroecological niches in the Rift Valley of Ethiopia. The soil samples were serially diluted and spread on starch casein agar medium supplemented with 50 μg/ml cycloheximide and 25 μg/ml nalidixic acid. Two hundred and forty-nine (249) actinomycetes cultures were isolated and screened by cross streaking against various human pathogens. Twenty-four isolates with pronounced antimicrobial activity were selected for identification and further screening. Among the isolates, 172 (69.1%) showed antimicrobial activities against tested pathogens. The inhibition zone of the isolates ranged from 5 ± 0.31 to >40 mm during primary screening. The antimicrobial activity of the crude extracts of promising isolates showed a statistically significant difference P < 0.05 between them and the control. The isolates RVE...
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Aggressiveness variation among the population of Colletotrichum kahawae representing seven major coffee-growing administrative zones of Ethiopia was studied under greenhouse conditions. The experiment was conducted through cross... more
Aggressiveness variation among the population of Colletotrichum kahawae representing seven major coffee-growing administrative zones of Ethiopia was studied under greenhouse conditions. The experiment was conducted through cross inoculation of eight Arabica coffee cultivars with seven C. kahawae isolates. The results revealed the presence of significant (p < 0.05) differences among coffee cultivars, isolates and their interactions. However, the large proportion of the variation was due to the main effects of the cultivars and the isolates. The interaction effect between cultivars × isolates was minimal, indicating that variation for virulence within C. kahawae is unlikely to occur. Although all of the isolates were pathogenic to the coffee cultivars tested, isolate CBD07 and CBD68 were the most aggressive followed by CBD184 and CBD156. On the other hand, except the coffee cultivar 741 and 971, the remaining coffee cultivars showed higher susceptibility reactions under greenhouse conditions. Moreover, cultivar 74110 and 1377 were extremely susceptible showing comparable disease reaction with the standard coffee berry disease (CBD) susceptible check ‘cv 370’. The study also showed that the mean disease incidence and severity of 72.5% and 56.2%, 70.7% and 56.2%, 69.6% and 54.4% were obtained with pathogen strains isolated from forest, semi-forest and garden coffee, respectively. Thus, the current variation in pathogenicity among the C. kahawae population is important in the development of disease resistant cultivars by considering the most aggressive isolates for successful screening of coffee germplasms for coffee berry disease resistance.
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In Ethiopia, coffee wilt disease (CWD) is increasingly important in all production systems. The current management methods, eradication of diseased trees, mulching, and protection by stem painting as preventive measures are not efficient.... more
In Ethiopia, coffee wilt disease (CWD) is increasingly important in all production systems. The current management methods, eradication of diseased trees, mulching, and protection by stem painting as preventive measures are not efficient. While searching for host resistance is most practical and effective approach for tracheomycosis control. To this end, 102 Arabica coffee germplasm collections conserved at Jimma, southwest Ethiopia, were tested for their reactions to CWD under greenhouse conditions. The screening trials were laid out in two sets in a RCBD with three replications. CWD resistant and susceptible checks were included for comparison. Stem nicking inoculation was employed with 2.1 × 10 conidia of Gibberella xylarioides isolate at cotyledon stage. Seedlings of 19 coffee accessions 279/71, 226/71, 259/71, 244/71, 120/71, 3/70, 16/70, 245/71, and 30/70 (batch I); and 27/77, 12/74, 26/77, B3/06, B2/06, 44/83, 48/83, B1/06, 11/77 and 13/74 (batch II) showed low death rate. Th...
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Isolation and characterization of nitrogen deficit Rhizobium isolates and their effect on growth of haricot bean
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Evaluation of locally available substrates for cultivation
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The current study is about isolation of some dominant microorganisms from compost of coffee wastes within Jimma Agricultural campus. Composting of coffee waste (husk) was conducted with cow dung, poultry manure and bone meal in the ratio... more
The current study is about isolation of some dominant microorganisms from compost of coffee wastes within Jimma Agricultural campus. Composting of coffee waste (husk) was conducted with cow dung, poultry manure and bone meal in the ratio of 3:1. Some physicochemical parameters temperature and pH were measured for composts of coffee husk + cow dung (A), coffee husk + poultry manure (B) and coffee husk + bone meal (C). Microbial dynamics were analyzed every five days of turning compost. Different biochemical tests such as KOH-test, motility, catalase, oxidase cytochrome test, oxidation fermentation test, Gram-staining and citrate utilization test were conducted for characterization of the obtained isolates. Data were computed using table and figure. SPSS version 16 was also used for data analyzing. Variations (p<0.05) were observed for both temperature and pH value based on type of composted materials and duration of compost. Changes in a number of microbial dynamics during compost...
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At present, coffee production is dramatically increasing in the world. Consequently, coffee husk are also increasing at the same time. In order to minimize this hazardous husk, the current study was initiated to evaluate the suitability... more
At present, coffee production is dramatically increasing in the world. Consequently, coffee husk are also increasing at the same time. In order to minimize this hazardous husk, the current study was initiated to evaluate the suitability of coffee husk for cultivation of commercial oyster mushroom species (Pleurotus ostreatus) after compositing with different main substrate combinations. Composting of coffee waste (husk) was conducted with cow dung, poultry manure and bone meal in the ratio of 3:1. During cultivation of mushroom, some biological efficient and other parameters were conducted. Data were analyzed using SPSS version 16. The substrate combinations of coffee husk showed a significant variation (p 0.05) in terms of yield on the first 5 and 10 days of composting. But, great variations (p<0.05) were generally detected between combinations A+B and A, and A+B and CH. Therefore, better yield of oyster mushroom was obtained after bioconversion of this cost-effective and cheap ...
Research Interests: Food Science, Biology, Mushroom, Pleurotus ostreatus, Bioconversion, and 3 moreOyster, Pleurotus, and husk
Plastic bag wastes pose serious environmental pollutions and health problems in humans and animals. The situation is worsened in economically disadvantaged countries like Ethiopia. The objective of this survey was to assess usage of... more
Plastic bag wastes pose serious environmental pollutions and health problems in humans and animals. The situation is worsened in economically disadvantaged countries like Ethiopia. The objective of this survey was to assess usage of plastic bags and their environmental impacts in Jimma City of Ethiopia. A semi-structured questionnaire was used to collect data from 230 randomly selected respondents. The results indicated that the larger proportion (176, 76.52%) of the respondents used plastic bags more frequently than any other plastic products regardless of their age, occupation, and economic and educational status. Low price (159, 69.13%) and easy availability (152, 66.08%) were the main reasons for the widespread utilization of these products. Among the practices used for disposal of plastic bag wastes, open dumping to surrounding areas (137, 59.56%) was a practice widely used by almost all the residents of the city. Some of the major problems were animal death (167, 72.60%), bloc...
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Research Interests: Microbiology, Chemistry, Food Science, Medicine, Bacteria, and 3 moreFermentation, Probiotic, and Lactic Acid
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Food-borne pathogens are one of the leading causes of illness and death particularly in developing countries. This study was aimed at analyzing the hygiene indicator microorganisms and pathogens of minced meat and contact surface... more
Food-borne pathogens are one of the leading causes of illness and death particularly in developing countries. This study was aimed at analyzing the hygiene indicator microorganisms and pathogens of minced meat and contact surface materials in butcher shops in Addis Ababa, Ethiopia. Additionally, a checklist was applied to evaluate the hygiene condition of the establishments, and a questionnaire/checklist was used to assess food safety knowledge of the food handlers. This study has indicated that the mean microbial counts (total aerobic mesophilic, staphylococci, Enterobacteriaceae, total coliforms, fecal coliforms, aerobic spores and yeasts/molds) of the minced meat and contact surface materials in butcher shops ranged between 2.35 and 6.50 log·cfu/g and between 1.80 and 6.30 log·cfu/cm2, respectively. The mean microbial counts of minced meat samples taken in the morning and afternoon showed statistically significant differences (p<0.05). The prevalence of E. coli, Salmonella, an...
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Identification of the yeast responsible for Injera fermentation is important in order to be more consistent and for scale-up of Injera production. In this study, yeast were isolated and identified from fermenting teff dough sample... more
Identification of the yeast responsible for Injera fermentation is important in order to be more consistent and for scale-up of Injera production. In this study, yeast were isolated and identified from fermenting teff dough sample collected from household, hotels, and microenterprises, Addis Ababa. Initially, the yeast obtained from fermenting teff dough of different sources were selected on the basis of their CO2 production potentials. Its DNA sequencing of isolated yeast identified Pichia fermentans, Pichia occidentalis, Candida humilis, Saccharomyces cerevisiae, and Kazachstania bulderi. The association of identified yeast to their sources indicated the presence of Pichia fermentans in fermenting dough samples collected from all sources whereas Kazachstania bulderi, Saccharomyces cerevisiae, and Candida humilis were shown to be present in samples collected from households, hotels, and microenterprises, respectively. The phenotypes and CO2 production potentials of this yeast were ...
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Objective:Evaluate for potential biocontrol agent by assessing isolates forin vitroinhibitory efficacy, probable mechanisms to inhibit fungal pathogen and effect on growth of Faba bean infected withF. solani.Methods:The effect of... more
Objective:Evaluate for potential biocontrol agent by assessing isolates forin vitroinhibitory efficacy, probable mechanisms to inhibit fungal pathogen and effect on growth of Faba bean infected withF. solani.Methods:The effect of Rhizobium isolates on the development of radial mycelium ofF. solaniin PDA medium were testedin vitro. The experiments were carried out using the dual culture technique. Isolates that showed inhibitory effect againstF. solaniin vitrowere tested to assess hydrolytic enzymes and growth promoting traits. Subsequently, the three Rhizobium isolates that showed the greatest inhibitions and their combinations were tested in the greenhouse againstF. solaniroot rot on seedlings by applying cell suspensions at three different times of exposure to the pathogen.Results:In dual culture, 27 rhizobium isolates inhibited the radial growth ofF. solanimycelium more than 25%. Isolates JU26(1), JU15(2) and Ho-1WG, inhibited fungal radial growth by 70.5 %, 64.7% and 63.7%, resp...
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Ethiopia has a high demand for baker’s yeast in the bread and beverage industries. Unfortunately, Ethiopia has no producing plant for baker’s yeast and instead relies on costly imports. The objective of this work was to identify the most... more
Ethiopia has a high demand for baker’s yeast in the bread and beverage industries. Unfortunately, Ethiopia has no producing plant for baker’s yeast and instead relies on costly imports. The objective of this work was to identify the most productive and useful indigenous baker’s yeasts isolated from local fermented foods and drinks, honey and Molasses using leavening ability as the major metric. Six of the test isolates produced a maximum cell mass at 30°C, pH of 5.5 and 48 hours of incubation. Isolate AAUTf1 did not produce hydrogen sulfide, while isolates AAUTf5, AAUTj15 and AAUSh17 produced low levels of this chemical, and isolates AAUMl20 and AAUWt21 produced high levels of hydrogen sulfide, neglecting their utility in baking. The leavening performance of isolates AAUTf1 (Candida humilis) and AAUTf5 (Kazachstania bulderi) had the highest dough volume of 131 cm3and 128 cm3respectively in 120 min. Isolates AAUSh17 (Saccharomyces cerevisiae) and AAUTj15 (Saccharomyces cerevisiae) ra...
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Phosphorus (P) is one of the major bioelements limiting agricultural production. Phosphate solubilizing fungi play a noteworthy role in increasing the bioavailability of soil phosphates for plants. The present study was aimed at isolating... more
Phosphorus (P) is one of the major bioelements limiting agricultural production. Phosphate solubilizing fungi play a noteworthy role in increasing the bioavailability of soil phosphates for plants. The present study was aimed at isolating and characterizing phosphate solubilizing fungi from different rhizospheres using both solid and liquid Pikovskaya (PVK) medium. A total of 359 fungal isolates were obtained from 150 rhizosphere soil samples of haricot bean, faba bean, cabbage, tomato, and sugarcane. Among the isolates, 167 (46.52%) solubilized inorganic phosphate. The isolated phosphate solubilizing fungi belonged to genera ofAspergillus(55.69%),Penicilliumspp. (23.35%), andFusarium(9.58%). Solubilization index (SI) ranged from 1.10 to 3.05. Isolates designated as JUHbF95 (Aspergillussp.) and JUFbF59 (Penicilliumsp.) solubilized maximum amount of P 728.77 μg·mL−1and 514.44 μg mL−1, respectively, from TCP (tricalcium phosphate) after 15 days of incubation. The highest (363 μg mL−1)...
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The main purposes of this study were to determine the bacteriological load and safety of some fresh vegetables irrigated with Awetu River in Jimma town, southwestern Ethiopia. Water and vegetable samples were collected from three... more
The main purposes of this study were to determine the bacteriological load and safety of some fresh vegetables irrigated with Awetu River in Jimma town, southwestern Ethiopia. Water and vegetable samples were collected from three different irrigation sites and analyzed for their bacteriological contaminants following standard procedures. The maximum overall means of aerobic mesophilic bacteria, Enterobacteriaceae, aerobic spore formers, staphylococci, and total and fecal coliform counts were 8.06, 7.10, 6.54, and 2.97 log CFU g−1 and 1036 and 716 MPN 100 mL−1, respectively. The microflora of vegetable samples was dominated by Bacillus species (32.7%) followed by Enterobacteriaceae (25%) and Micrococcus (16%). Staphylococcus aureus and Salmonella spp. were detected in 24.0% and 20.7% of the samples, respectively. All the Staphylococcus aureus isolates were resistant to ampicillin, cefuroxime sodium, and penicillin G (100.0% each). All the Salmonella isolates were also resistant to te...
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A cross-sectional experimental study was conducted in Jimma town from November 2010 to March 2011 with the objectives of studying Listeria monocytogenes and other Listeria species in milk and milk products. Samples were collected from... more
A cross-sectional experimental study was conducted in Jimma town from November 2010 to March 2011 with the objectives of studying Listeria monocytogenes and other Listeria species in milk and milk products. Samples were collected from cafes, milk product shopping and pastries . From total of 200 samples (milk, cottage cheese, ice cream and yoghurt) examined Listeria was isolated from 13(6.5%). The frequency of isolation and distribution of Listeria in different food samples was analyzed and the difference in prevalence among different food samples: was not statistically significant (P> 0.05). Prevalence of Listeria was higher 7 (14%) in milk samples followed by ice cream 3(6%), yoghurt 2(4%) and cottage cheese 1(2%). The study shows significant variation (P< 0.05) in distribution of Listeria species in food samples. The dominant Listeria species isolated was Listeria monocytogenes 8(4%) followed by Listeria innocua 3(1.5%) and Listeria seeligeri 2(1%).
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The experiment was carried out to evaluate the antifungal potential of aqueous and ethanolic extracts of four spices (Allium sativum, Zingiber officinale, Cinnamomum zeylanicum and Capsicum annuum) against the important post-harvest... more
The experiment was carried out to evaluate the antifungal potential of aqueous and ethanolic extracts of four spices (Allium sativum, Zingiber officinale, Cinnamomum zeylanicum and Capsicum annuum) against the important post-harvest spoilage fungi isolated from diseased fruits. In total, 276 isolates of post-harvest spoilage fungi were isolated from four different fruit types (Persea americana, Musa acuminate, Citrus sinensis and Lycopersicom esculentum), out of which 183 isolates were identified while 93 isolates were remain unidentified. The most dominant post-harvest spoilage fungus was Rhizopus sp., (26.45%), followed by Penicillium sp., (19.93%), Aspergillus sp., (10.86%) and Fusarium sp., (9.06%). Results of disc diffusion assay showed that ethanolic extract of C. zeylanicum was found to be most effective against Penicillium sp., followed by aqueous extracts of A. sativum. The ethanolic extract of C. zeylanicum in agar amended assay and minimal inhibitory concentrations was fo...
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This focus piece comes out of a recognition that higher institutions can and must play a key role in transforming the gendered landscape of food security. Close to 70% of labour related to post-harvest in Ethiopia is carried out by women.... more
This focus piece comes out of a recognition that higher institutions can and must play a key role in transforming the gendered landscape of food security. Close to 70% of labour related to post-harvest in Ethiopia is carried out by women. However, this does not mean that decision-making in a family (about what to grow or how to market it)
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Degradation and loss of arable lands have attracted attention of the scientists worldwide to protect lands from further declining. The multifaceted functions of legumes on the other hand in the improvement of natural and managed... more
Degradation and loss of arable lands have attracted attention of the scientists worldwide to protect lands from further declining. The multifaceted functions of legumes on the other hand in the improvement of natural and managed terrestrial ecosystems have necessitated their sustainable production. Leguminous crops are the important protein source in human dietary systems particularly in developing countries. The legume productions have, however, been seriously hampered due to heavy metal contamination of soils. Maintenance of soil quality adopting various remediation strategies including biological approaches is therefore important. Mycorrhizoremediation among bioremediation has currently been the focus of research. Arbuscular mycorrhizal fungi (AMF) establish mutual symbioses with the majority of higher plants and after colonization, contribute to the plant growth in metal-contaminated sites by increasing plant access to P, by improving soil quality, and by restricting the movement of metals within plant tissues. Here, we have focused to understand on how the heavy metals affect legumes and the incidence of AMF in metal-polluted sites. In addition, the role of AMF in restoring heavy metal-contaminated sites is described. Understanding the role of mycorrhizae in metal detoxification is likely to improve the agronomic strategies in order to take full advantage of mycorrhizal association for legume production in disturbed cropping locations.
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... The absence of mineral N limited growth of A. colubrina and P. rigida, but ... leguminous plants grown in stressed situations have also been well documented (Sharma et al. ... However, plant species did not show any correlation... more
... The absence of mineral N limited growth of A. colubrina and P. rigida, but ... leguminous plants grown in stressed situations have also been well documented (Sharma et al. ... However, plant species did not show any correlation between percentage mycorrhizal infection and growth. ...