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Articles by Diriba Muleta
Total Records ( 5 ) for Diriba Muleta
  Melkamu Tiru , Diriba Muleta , Gezahegn Berecha and Girma Adugna
  This study was designed to evaluate the antagonistic effects of rhizobacterial antagonists against Coffee Wilt Disease (CWD) caused by Gibberella xylarioides under in vitro and in vivo conditions. Arabica coffee is Ethiopia’s main export crop. However, the production and productivity of coffee is being challenged primarily by coffee vascular disease (tracheomycosis).The greenhouse antagonism study was conducted with four antagonistic bacteria of one Bacillus (JU544) and three Pseudomonas spp. (JU941, JU13 and JU23). Out of 81 rhizobacterial antagonists tested on Half Strength King’s B (HSKB) medium against G. xylarioides, 13.6% of them significantly (p<0.0001) reduced the radial mycelial growth of the pathogen. From 11 rhizobacterial isolates tested for their phytobeneficial traits, eight of them produced protease. Nevertheless, five of them produced Hydrogen Cyanide (HCN) and other lytic enzymes. The bio-control agents, time of applications and the interaction of the two were significantly (p<0.0001) reduced the CWD severity and incidence under greenhouse conditions. The CWD control efficiency was significant (p<0.0001) and the highest bio-control efficiency was 72.64% when the coffee seedlings were treated with Bacillus spp. (JU544) seven days before the pathogen. The bacterial antagonists, time of applications and interaction of the two significantly (p<0.001) reduced the progression of CWD incidence. The rhizobacterial antagonists especially Bacillus spp. (JU544) effectively reduced CWD severity and incidence under greenhouse condition and can be further evaluated under field condition to ascertain their future applicability for inoculum development.
  Amsalu Abera , Fikre Lemessa and Diriba Muleta
  This study was carried out with the objective of evaluating the antifungal potential of aqueous and ethanol extracts of eight different plant species in vitro and in vivo against Colletotrichum kahawae in completely randomized design with three replications. The extracts were from Hagenia abyssinica, Allium sativum, Phytolacca dodcandera, Croton macrostachyus, Maesa lanceolata, Eucalyptus globules, Eucalyptus citriodera and Lippia adoensis. Subsequently, two most effective plant extracts were tested in vivo against the disease on detached green coffee berries and seedling applying the extracts at 3 different times of application (at the time of inoculation and 48 h before and after inoculation) on the pathogen. The study indicated that the inhibitory effect of the extracts depended on the type of plant species used, method of extraction and time of application of the extracts. Generally, A. sativum and C. macrostachyus aqueous and ethanol extracts were the most effective plants that significantly reduced radial growth of the pathogen compared to the control. A. sativum reduced radial growth of the pathogen in ethanol and aqueous extracts by 83 and 100%, respectively and C. macrostchyus by 68 and 88%, respectively. Furthermore, A. sativum extracts consistently reduced disease severity on detached green berries and seedling in greenhouse at all times of application. Nevertheless, the efficacy of C. macrostachyus on detached green berries and seedlings was inconsistent and variable based on method of extraction and time of application of the extracts. The study indicated the possible use of extracts of A. sativum as an alternative means of CBD (coffee berry disease) management but further study at field conditions should be carried out to verify the result.
  Shiferaw Demissie , Diriba Muleta and Gezahegn Berecha
  The aim of this study was to evaluate effect of phosphate solubilizing bacteria on seed germination and seedling growth of Faba bean (Vicia faba L.) under lath-house condition. Phosphorous is an essential macronutrient next to nitrogen required by the plants for vital biosynthesis. But often unavailable for plants because of adsorbed by Ca2+, Mg2+, Fe2+ and Al3+ ions through legend exchange. Although there is mounting information that phosphorus solubilizing bacteria as inoculants increases P uptake of plants. This was not yet tested on Faba bean in Ethiopia. A total of 183 phosphate solubilizing bacteria were isolated from 150 samples collected from rhizosphere soil and root nodules. From these isolates based on their solublization index and mobilization efficacy, two isolates (JURB48 and JURMB69) were selected and tested on Faba bean. The co-inoculants (JURB48+JURMB69) increased the percentage of seed germination (21.4%), vigor index (46.2%), radicle (25.3%) and plumule (50%) lengths of germinated seeds of Faba bean over the non-inoculated. Faba bean shoot fresh, root weight, leaf number, flower number, root dry weight and total dry matter were significantly increased compared to non-inoculated as a result of co-inoculants (JURB48+JURMB69). Plant height, root length, phosphorus content, P uptake and Nodule number and weight were enhanced due to inoculation with JURB48 and JURMB69, respectively, compared to non-inoculated either in the presence or absence of phosphate sources. The present study suggests the potential of JURB48 and JURMB69 isolates as biofertilizers for Faba bean cultivation.
  Shiferaw Demissie , Geda Kebede , Diriba Muleta and Anbessa Dabassa
  Awetu is the River which passes through Jimma town of south western Ethiopia, and one of the major water resources for irrigation and domestic activities for the area. Improper utility of contaminated water create unlimited health concern for the society that utilizing the water for farm and domestic activities. This study was important to evaluate the microbial load, protolytic and lipolytic activities of the isolated microorganisms. The results showed great number of bacterial contaminant in the river. Mainly, Aerobic mesophilic, Enterobacteriaceae, Staphylococcus and aerobic spore formers bacteria range between 103-106 CFU 100 mL-1 while yeast and mold ranged between <30 to 103. In a total of 30 samples were analyzed for microbial load determination using conventional culture method. The results of the this study indicate that the human and cattle feces, domestic activities, as well as solid and liquid waste disposal around the river were the main sources of contamination potential of water. Therefore, continuous and accurate assessment of the quality of water had a paramount importance. In addition, the presence of fecal contaminants in the three sites along the river segment indicates the problem of the water quality. Possible remedial actions are needed as recommendations in this study.
  Mulugeta Tesemma , Legesse Adane , Yinebeb Tariku , Diriba Muleta and Shiferaw Demise
  The main objective of this study was to isolate compounds from root wood of Moringa stenopetala and evaluate antibacterial activities of the isolated compounds. Crude gradient extracts were obtained from five solvents (petroleum ether, chloroform, acetone, methanol and water) with increasing solvent polarity using cold maceration technique. The in vitro antibacterial activity evaluation of gradient extracts and isolated compounds was done on four different pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella Typhimurium) using agar disc diffusion technique. Among the five crude extracts evaluated, the acetone extract was found to be the most active against the tested strains. Thus, this extract was subsequently subjected to column chromatographic separation which led to isolation of four compounds (MS-1, MS-2, MS-3 and MS-4). The chemical structures of the compounds were found to be cholest-5-en-3-ol, palmitic acid, n-octacosane and oleic acid, respectively, based on physical properties and spectroscopic (IR and NMR) data as well as literature reports. Three of the compounds namely cholest-5-en-3-ol, palmitic acid and oleic acid showed highest activity against E. coli. The observed antibacterial activities of the crude extract and the isolated compounds could justify the traditional use of the plant for the treatment of different bacterial infections. Thus, further test is recommended on large number of bacterial strains to decide their potential as candidates in development of antibacterial drugs.
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