Biology

Mesorhizobium species. Therefore, this study was aimed at isolation, characterization and selection of symbiotically effective native chickpea nodulating rhizobia endowed with different plant growthpromoting (PGP) characteristics. Hence, phenotypic and plant growth promoting characteristics of thirty-six rhizobia isolates recovered from root nodules of chickpea grown in soils collected from different chickpea producing areas found in Central and Northern part of Ethiopia were investigated. The result of our study indicated that chickpea rhizobial isolates have shown wide diversity in their different C and N-sources utilization pattern and tolerance to salinity, high temperatures, acid and alkaline pH, heavy metals and antibiotics. Symbiotic and morphological characterization also showed a wide diversity among tested isolates. Moreover, screening for PGP characteristics indicated that 44.4% of the isolates were phosphate solubilizer while 27.8% of them were found to be indole-3-acetic acid (IAA) producer. Furthermore, 19.4% tested isolates showed antagonistic activity against Fusarium oxysporum in dual culture assay. Generally, the present study indicates that Ethiopian soils contain symbiotically effective chickpea nodulating rhizobia which are endowed with different PGP characteristics.

Faba bean is one of the legume crops commonly grown in Ethiopia. It is important source of dietary protein to the majority of population in the country. Soil acidity and related stresses are among the major yield limiting constraints for this crop. This study was conducted with the aim of evaluating acidity tolerance of Rhizobium leguminosarum bv. viciae strains isolated from faba bean growing regions of the country and their symbiotic performance under different acidic conditions. Four strains isolated from root nodules of faba bean were tested for tolerance to acidity in a defined liquid media. The results indicated that none of the tested strains was tolerant to pH 4.0 while two of them (AUFR46 and AUFR100) were found to be tolerant of pH 4.5. When tested at pH 5.0 only one isolate (AUFR58) was sensitive. The results of the present study also showed that all acid tolerant strains were recovered from highly acidic soil (4.8-5.2) and the acid sensitive strain was isolated from neutral soil. A positive correlation (r= 0.92) was observed between minimum pH tolerated in culture media and pH of origin soil of the strains. Nodulation and nitrogen fixation abilities of these strains were evaluated on sand culture. The results indicated that at pH 4.5 and 5.0 nodulation was totally inhibited and only one isolate (AUFR58) could not be able to induce nodule formation on host plant roots at pH 5.5. The results also showed that acidity (pH 5.5) reduced shoot dry weight, nodules number, total nitrogen at a highly significant level (P<0.01) compared to plants grown at pH 6.5 and 7.0. In pot experiment with soil of different pH, inoculation of the rhizobial strains improved the growth, nodulation and nitrogen content of the plants significantly over the uninoculated controls. Besides, acid tolerant strains showed better performance over acid sensitive strains in acidic soils and thus, they are highly recommended for field test in acidic soil.

It also maintains soil fertility through symbiotic nitrogen-fixation in association with Rhizobium leguminosarum bv. viciae. The aim of this study was selecting symbiotically efficient native lentil nodulating rhizobia endowed with different plant growth-promoting (PGP) characteristics. Hence, 30 lentil nodulating rhizobial isolates were isolated from soils collected from different farmer fields found in Central and Northern parts of the country. All isolates were characterized based on morphological, physiological, symbiotic and PGP characteristics. The result of this study showed that these isolates have exhibited interesting features such as wide range of carbon-sources and nitrogen sources utilization, tolerance to acidic and alkaline pH, metal toxicity and antibiotics. Symbiotic characterization indicated that all tested isolates have showed great diversity in their capacity to nodulate their host plant and produce shoot dry matter yield under glasshouse conditions. In addition, they showed PGP characteristics such as IAA production and inorganic phosphate solubilization. Out of all tested isolates 36.7% of them were IAA producer while only 16.7% were insoluble inorganic phosphate solubilizer. In general, from the present study, it can be concluded that Ethiopian soils harbor highly efficient nitrogen-fixing lentil nodulating rhizobia which are diverse in their morphological, physiological and symbiotic characteristics.

Chickpea (Cicer arietinum L.) is one of the major sources of dietary protein for majority of Ethiopian
population. It also maintains soil fertility through its symbiotic nitrogen-fixation in association with
Mesorhizobium species. Therefore, this study was aimed at isolation, characterization and selection of
symbiotically effective native chickpea nodulating rhizobia endowed with different plant growthpromoting
(PGP) characteristics. Hence, phenotypic and plant growth promoting characteristics of
thirty-six rhizobia isolates recovered from root nodules of chickpea grown in soils collected from
different chickpea producing areas found in Central and Northern part of Ethiopia were investigated.
The result of our study indicated that chickpea rhizobial isolates have shown wide diversity in their
different C and N-sources utilization pattern and tolerance to salinity, high temperatures, acid and
alkaline pH, heavy metals and antibiotics. Symbiotic and morphological characterization also showed a
wide diversity among tested isolates. Moreover, screening for PGP characteristics indicated that 44.4%
of the isolates were phosphate solubilizer while 27.8% of them were found to be indole-3-acetic acid
(IAA) producer. Furthermore, 19.4% tested isolates showed antagonistic activity against Fusarium
oxysporum in dual culture assay. Generally, the present study indicates that Ethiopian soils contain
symbiotically effective chickpea nodulating rhizobia which are endowed with different PGP
characteristics.

Biological wastewater treatment is economically feasible and ecofriendly. This study was aimed at isolating bacteria from brewery wastes and evaluating their bioremediation potential as individual isolate and/or their consortium in reducing the pollutants of brewery effluents. A total of 40 bacterial isolates were recovered and of these the three best isolates were selected. The selected bacteria were identified to genus level by using morphological and biochemical characteristics. Accordingly, the isolates were identified as Aeromonas sp., Pseudomonas sp., and Bacillus sp. After 12 days of incubation, the removal efficiency of these three isolates and their combinations for biological oxygen demand and chemical oxygen demand varied from 73.55% to 94.85% and 76.78% to 93.25%, respectively. Total nitrogen and phosphorus removal was within the range of 54.43% to 77.21% and 41.80% to 78.18%, respectively. Total suspended solid, total solid, and total dissolved solids removal ranged fro...

In Ethiopia, access to improved water supply and sanitation has been very low and hence majority of the communicable diseases are associated with unsafe and inadequate water supply. Thus, the aim of this study was to assess physicochemical and bacteriological characteristics of water from sources to household connection in Nekemte town. A cross-sectional study was conducted from November 2015 to March 2016. Water samples were collected in triplicates from selected 30 sampling points from source, disinfection point, main distribution system tank, and household taps. All samples were analysed for bacteriological, chemical, and physical quality parameters using standard procedures. The results showed that temperature, pH, turbidity, total dissolved substances, and electrical conductivity of the water samples were varied between 16.9 and 22°C, 6.8–7.0, nil-12 NTU, 50–70 mg/l, and 40–46 µS/cm, respectively. Phosphate and nitrate concentrations of the water samples also ranged between 0.6...

Chickpea ( Cicer arietinum L.) is one of the major sources of dietary protein for majority of Ethiopian population. It also maintains soil fertility through its symbiotic nitrogen-fixation in association with Mesorhizobium species. Therefore, this study was aimed at isolation, characterization and selection of symbiotically effective native chickpea nodulating rhizobia endowed with different plant growth promoting (PGP) characteristics. Hence, phenotypic and plant growth promoting characteristics of thirty-six rhizobia isolates recovered from root nodules of chickpea grown in soils collected from different chickpea producing areas found in Central and Northern part of Ethiopia were investigated. The result of our study indicated that chickpea rhizobial isolates have shown wide diversity in their different C and N-sources utilization pattern and tolerance to salinity, high temperatures, acid and alkaline pH, heavy metals and antibiotics. Symbiotic and morphological characterization a...

Lentil (Lens culnaris Medik.) is an invaluable source of dietary protein for the majority of Ethiopian population. The low availability of phosphorus is one of the major soil related stresses that limit the production of this crop. This study was aimed at isolation and characterization of phosphate solubilizing bacteria from lentil growing areas of Ethiopia and evaluating their effects on growth of this crop under greenhouse conditions. In total, 41 phosphate solubilizing bacterial strains were isolated from lentil rhizosphere and characterized using biochemical tests and 16S rDNA sequence analysis. The results showed the presence of genera Acinetobacter, Agrobacterium, Bacillus, Burkholderia, Chryseomonas, Enterobacter, Pseudomonas, Ralstonia and Sphingomonas. Phosphate solubilzing efficiencies of these isolates were evaluated in liquid medium using different insoluble P-sources and the result indicated that they released considerable amount of phosphates from tricalcium phosphate, rock phosphate and bone meal. Besides, some of these isolates exhibited multiple plant growth promoting characteristics such as indole acetic acid production and growth inhibition of Fusarium oxysporum under in vitro conditions. The effects of inoculation of Enterobacter kobei (PSBL5), Bacillus subtilis (PSBL21), Enterobacter species (PSBL26), Bacillus species (PSBL31) and Pseudomonas fluorescence (PSBL37) on lentil growth, nodulation, N and P content of shoot were evaluated under a greenhouse conditions and the results showed that these features were significantly increased over uninoculated control plants. Based on the results of this study, we conclude that lentil rhizosphere soil from producing areas of Ethiopia harbor diverse phosphate solubilizing bacterial strains with excellent phosphate solubilization and plant growth promotion ability. Thus, most of the promising strains should be tested in the field conditions under different agroecology of the country.

Chickpea is one of the major legume crops widely grown in Ethiopia. The low availability of phosphorus in soil is among the stresses that constrain the production of this crop in the country. However, there are rhizobacteria capable of solubilizing insoluble forms of phosphorus in soil and make it available to the plant. Thus, this study was aimed at isolation and characterization of phosphate solubilizing bacteria from chickpea rhizosphere. Fifty phosphate solubilizing bacterial strains were isolated from the soil samples, characterized biochemically and identified by 16S rDNA sequences analysis. The results indicate the presence of genera Acinetobacter, Bacillus, Brevibacillus, Burkholderia, Empedobacter, Enterobacter, Pseudomonas, Ralstonia, Sphingomonas and Stenotrophomonas. Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes showed that 44 and 18% of them were capable of producing indole acetic acid and inhibiting the growth of Fusarium oxysporum under in vitro conditions, respectively. A direct impact of several strains (Bacillus flexus (PSBC17), Pseudomonas fluorescence (PSBC33), Enterobacter sp. (PSBC35), Enterobacter sakazaki (PSBC79) and Enterobacter sp. (PSBC81)) on the growth of chickpea in pot culture has been demonstrated by the increase in the number of root nodules, shoot dry matter, nitrogen and phosphorus concentration of shoot. Based on the results, we conclude that chickpea rhizosphere harbor phosphate solubilizing bacteria which are diverse in taxonomy and phosphate solubilizing efficiencies. Thus, consecutive studies should focus on field studies on those strains due to their potentially high importance for the phosphorus nutrition of crops in this area and in this context for the improvement of the sustainability of crop production in the country.

The quality of drinking water has always been a major public health concern, especially in developing countries where access to improved water supply and sanitation is very low. This study aimed to assess the bacteriological and physicochemical quality of rural community drinking water sources in the Guto Gida district. A cross-sectional study was conducted in selected rural areas of the district from January to June 2016. Water samples were collected from four types of sources (protected dug well, open dug well, protected spring, and open spring) found in 8 locations of the study area. The membrane filtration technique was employed to determine the total coliform and faecal coliform load of the samples. The physicochemical characteristics such as total dissolved solid (TDS), pH, electrical conductivity (EC), turbidity, temperature, color, iron, manganese, lead, fluoride, zinc, sulphate, nitrate, and phosphate were analyzed following the American Public Health Association and WHO st...

Large quantities of bagasse are regularly accumulated on open spaces around sugar factory thereby endangering fragile ecosystem. The sugar cane bagasse carbonization process can be put into effect as an environmentally friendly, energy self-providing continuous flow technology. Therefore, the objective of this study was to use bagasse for the production of high caloric value briquette to safeguard the environment from pollution. Bagasse sample was collected from Wonje sugar factory and carbonized in an oxygen deficient environment at Ethiopian Rural Energy Development and Dissemination Center Laboratory, Addis Ababa. The carbonized materials were mixed with clay and molasses as a binder in different ratio to make a briquette using briquette extruder machine. Caloric value of the briquettes produced from bagasse using clay and molasses as a binder in different ratio ranged between 3,529-4,064 and 3,964-4,442 cal/g, respectively. The highest caloric value using clay as a binder was in the ratio 20:80 and the lowest caloric value using molasses as a binder was in the ration 25:75. Further analysis showed that through conversion of bagasse from Wonji sugar factory into briquette, annually the factory could generate 3.1×10-10 cal of energy and substitutes 13.01 m 3 of firewood or save 0.13 to 0.16 ha of tropical forests from deforestation and have the potential to sequestrate 17.90 to 22.03 tons of carbon annually. Further, the study concluded that briquettes produced from bagasse could be used as a quality source of energy and bagasse waste management option around sugar industry.

Edible mushrooms are seen as a way of increasing dietary diversity and achieving food security in Ethiopia. The aim of this study was to develop substrates using locally available agro-industrial by-products and animal manures to enhance the production of Shiitake (Lentinula edodes) mushrooms in Ethiopia. The hypothesis was L. edodes mushroom production on seven different substrates: 100% sugarcane bagasse (S1), 80% sugarcane bagasse, 20% cow dung (S2), horse manure (S3), chicken manure (S4), cottonseed hulls (S5), sugarcane filter cake (S6), and sugarcane trash (S7). Mushroom yield and biological efficiency were significantly affected by substrate type (p &lt; 0.05). A significantly higher yield (434.33 g/500 g of substrate) and biological efficiency (86.83%) were obtained using substrate S4 while lower yield (120.33 g/500 g) and biological efficiency (24.33%) were obtained using substrate S7 than when using other substrates. The largest first flush of mushrooms was obtained on S4,...

Article Information Faba bean is one of the legume crops commonly grown in Ethiopia. It is important source of dietary protein to the majority of population in the country. Soil acidity and related stresses are among the major yield limiting constraints for this crop. This study was conducted with the aim of evaluating acidity tolerance of Rhizobium leguminosarum bv. viciae strains isolated from faba bean growing regions of the country and their symbiotic performance under different acidic conditions. Four strains isolated from root nodules of faba bean were tested for tolerance to acidity in a defined liquid media. The results indicated that none of the tested strains was tolerant to pH 4.0 while two of them (AUFR46 and AUFR100) were found to be tolerant of pH 4.5. When tested at pH 5.0 only one isolate (AUFR58) was sensitive. The results of the present study also showed that all acid tolerant strains were recovered from highly acidic soil (4.8-5.2) and the acid sensitive strain was isolated from neutral soil. A positive correlation (r= 0.92) was observed between minimum pH tolerated in culture media and pH of origin soil of the strains. Nodulation and nitrogen fixation abilities of these strains were evaluated on sand culture. The results indicated that at pH 4.5 and 5.0 nodulation was totally inhibited and only one isolate (AUFR58) could not be able to induce nodule formation on host plant roots at pH 5.5. The results also showed that acidity (pH 5.5) reduced shoot dry weight, nodules number, total nitrogen at a highly significant level (P<0.01) compared to plants grown at pH 6.5 and 7.0. In pot experiment with soil of different pH, inoculation of the rhizobial strains improved the growth, nodulation and nitrogen content of the plants significantly over the uninoculated controls. Besides, acid tolerant strains showed better performance over acid sensitive strains in acidic soils and thus, they are highly recommended for field test in acidic soil.

Lentil (Lens culnaris Medik.) is an invaluable source of protein for the vast majority of Ethiopian people. It also maintains soil fertility through symbiotic nitrogen-fixation in association with Rhizobium leguminosarum bv. viciae. The aim of this study was selecting symbiotically efficient native lentil nodulating rhizobia endowed with different plant growth-promoting (PGP) characteristics. Hence, 30 lentil nodulating rhizobial isolates were isolated from soils collected from different farmer fields found in Central and Northern parts of the country. All isolates were characterized based on morphological, physiological, symbiotic and PGP characteristics. The result of this study showed that these isolates have exhibited interesting features such as wide range of carbon-sources and nitrogen sources utilization, tolerance to acidic and alkaline pH, metal toxicity and antibiotics. Symbiotic characterization indicated that all tested isolates have showed great diversity in their capacity to nodulate their host plant and produce shoot dry matter yield under glasshouse conditions. In addition, they showed PGP characteristics such as IAA production and inorganic phosphate solubilization. Out of all tested isolates 36.7% of them were IAA producer while only 16.7% were insoluble inorganic phosphate solubilizer. In general, from the present study, it can be concluded that Ethiopian soils harbor highly efficient nitrogen-fixing lentil nodulating rhizobia which are diverse in their morphological, physiological and symbiotic characteristics.

The main objective of this study was determining the prevalence and antibiotics resistance pattern of Salmonella and Shigella sp. from diarrheal patients attending Nekemte Referral Hospital. A total of 422 patients were included in the study and their sociodemographic and clinical information was collected using questionnaire. Stool samples of the patients were collected and processed following standard bacteriological protocols. Presumptive colonies of Salmonella and Shigella species were identified and subcultured to their respective genera by standard biochemical tests. Antibiotics susceptibility of the isolates was tested using disk diffusion assay. The prevalences of Salmonella and Shigella sp. among the patients were 7.1% and 2.1%, respectively. The antimicrobial susceptibility test results of the isolates showed that they are highly resistant to amoxicillin (30 g). In contrast, the isolates showed relatively lower resistance level to ceftriaxone (30 g), nalidixic acid (30 g), norfloxacin (10 g), and ciprofloxacin (5 g). This study revealed 9.2% prevalence of Salmonella and Shigella sp. which were resistant to commonly prescribed antibiotics. Thus, intervention measures such as health education, provision of safe drinking water, improvement of waste disposal systems, and surveillance of antibiotics susceptibility of the pathogens should be done regularly.

Article Information Some species of rhizobial bacteria nodulating faba bean are characterized by phosphate solubilization. In order to study their in vitro and symbiotic characteristics, twelve rhizobial isolates nodulating faba bean were collected from acidic soil of Wollega, Ethiopia. Solubilization index of the isolates ranges from 1.25 to 2.10. Mean Generation Time of the isolates were less than 2.34; and growth of isolates on Yeast Extract Mannitol agar with bromothymoleblue media were accompanied by change of color from blue to yellow. AUAVR-51 and AUAVR-52 were the highest in TCP-Solubilizion Index. The two isolates were also recognized as stress tolerant when tested in vitro for extreme temperature, osmotic, acidic pH, intrinsic antibiotics, and acidic-aluminum as compared to the other isolates. However, there was no unique metabolic diversity and specialization of AUAVR-51 and AUAVR-52 isolates with respect to carbon and nitrogen source utilization. On the other hand, isolates AUAVR-51 and AUAVR-52 were characterized by effective and highly effective symbiosis on sterile potted sand growth, respectively. In general, phosphate solubilizing rhizobia nodulating faba bean from acidic soil are fast grower; and their solubilization potential varies. However, the contribution of these isolates as double fertilizer should be tested in the real acidic soil characterized by immobilized phosphorous.

In Ethiopia, access to improved water supply and sanitation was estimated at 38% and 12% respectively. Three-forth of the health problems of children in Ethiopia are communicable diseases due to polluted water and improper water handling practices. Thus, this study was conducted to assess the level of contamination and the major sources of contaminant in rural communities of Dire Dawa. A total of 90 water samples from five types of water sources were collected and bacteriological water quality parameters were analyzed using the membrane filtration method by the procedures of the American Public Health Association. Water analysis demonstrated that all water sources in the study areas were contaminated with total coliforms, fecal coliform and parasites. The average counts of TC were in the range of 1.5-133.05CFU/100ml whereas the average counts of FC were found to be 0.34-54CFU/100ml. The mean concentration of Giardia lamblia and Cryptosporidium ranges from 0 to 5.6 and 0 to 6.5, respectively. In all samples, the TC, FC and FS counts were above the recommended limit of WHO for drinking water quality (1-10CFU/100ml for TC, 0CFU/100ml for FC, 0CFU/100ml FS) whereas about 83.34% of the water samples in the three selected PAs had high risk of microbiological water quality parameters. Fecal coliform -fecal streptococci ratios in all water sources in this study showed that 45.0% indicated enteric contamination from human wastes and 55.0% was from domestic animal wastes. High concentration of microbiological indicators in all water sources of this study area suggested that the presence of pathogenic organisms which constitute a threat to anyone consuming or in contact with these waters. This is due to lack of good water treatment, lack of feasible disinfection, improper water handling practices and lack of the protection of the water sources. Consequently, protection of water sources accompanied by sanitation and hygiene promotion programs can improve the water quality of rural water sources, where disinfection is not feasible. Proper and basic sanitation, are of prime importance to deliver safe drinking water in the study site.