Enset is a perennial root crop indigenous to Ethiopia cultivated dominantly in the south and southwestern highlands. There are several enset varieties or clones mainly produced for their starch from the pseudostem while some are exclusively cultivated for their corm. Kocho, bulla, and corm (amicho) are the main food products of enset. We studied the nutritional, socio-economic, and cultural values of this crop. The corm (Neqaqa) was found to be more nutritious than bulla (Gena) except in starch and zinc contents. Enset is rich in starch but low in protein composition hence, dietary protein source is mandatory. It plays great role in the food security of the country and a staple food for significant Ethiopian population. It has several environmental, nutritional, and socio-cultural importance however its cultivation is under disease challenges. Continuous research effort is required to improve the production of enset and its food products and fiber processing.

Ethiopia is the largest wheat producer in sub-Saharan Africa yet remains a net importer. Increasing domestic wheat production is a national priority. Improved varieties provide an important pathway to enhancing productivity and stability of production. Reliably tracking varietal use and dynamics is a challenge, and the value of conventional recall surveys is increasingly questioned. We report the first nationally representative, large-scale wheat DNA fingerprinting study undertaken in Ethiopia. Plot level comparison of DNA fingerprinting with farmer recall from nearly 4000 plots in the 2016/17 season indicates that only 28% of farmers correctly named wheat varieties grown. The DNA study reveals that new, rust resistant bread wheat varieties are now widely adopted. Germplasm originating from CGIAR centres has made a significant contribution. Corresponding productivity gains and economic benefits have been substantial, indicating high returns to investments in wheat improvement. The study provides an accurate assessment of wheat varietal status and sets a benchmark for national policy-makers and donors. In recent decades, the Ethiopian wheat landscape has transformed from local tetraploid varieties to widespread adoption of high yielding, rust resistant bread wheat. We demonstrate that DNA fingerprinting can be applied at scale and is likely to transform future crop varietal adoption studies.

The kinetic and thermodynamic parameters of wheat β-amylase (WBA) were characterized and various additives were evaluated for enhancing its activity and thermostability. WBA activity was examined by neocuproine method using soluble starch as substrate. The Michaelis constant (K(m)) and molecular activity (k(cat)) were determined to be 1.0±0.1% (w/v) and 94±3s(-1), respectively, at pH 5.4 and at 25°C. The optimum reaction temperature (T(opt)) for WBA activity was 55°C and the temperature (T(50)) at which it loses half of the activity after 30-min incubation was 50±1°C. Modifications of the solvent with 182mM glycine and 0.18% (w/v) gelatin have increased the T(50) by 5°C. Glycerol, ethylene glycol, dimethylformamide (DMF) and dimethyl sulfoxide have also slightly enhanced the thermostability plausibly through weakening the water structure and decreasing the water shell around the WBA protein. Ethanol and DMF activated WBA by up to 24% at 25°C probably by inducing favorable conformation for the active site or changing the substrate structure by weakening the hydrogen bonding. Its half-life in the inactivation at 55°C was improved from 23 to 48min by 182mM glycine. The thermodynamic parameters indicate that WBA is thermo-labile and sufficient stabilization was achieved through solvent modification with additives and that the heat inactivation of WBA is entropic-driven. It is suggested that WBA could be applied more widely in starch-saccharification industries with employing suitable additives.

Inhibition of wheat β-amylase (WBA) by glucose and maltose was studied by kinetics and thermodynamics. The inhibitory effects of fructose, difructose, sucrose, trehalose, cellobiose, acarbose, and 1-deoxynojirimycin on WBA were also evaluated. The half maximal inhibitory concentrations (IC50) of acarbose, maltose and glucose were 0.06±0.01M, 0.22±0.09M, and 1.41±0.17M, respectively. The inhibitor constant (Ki) and the thermodynamic parameters such as changes in Gibbs energy (ΔG), enthalpy (ΔH), and entropy (ΔS) of the dissociation reactions of the WBA-glucose and WBA-maltose complexes were temperature and pH-dependent. The dissociation reactions were endothermic and enthalpy-driven. Both glucose and maltose behaved as competitive inhibitors at pH 3.0 and 5.4 at a temperature of 25°C with respective Ki values of 0.33±0.02M and 0.12±0.03M. In contrast, both sugars exhibited uncompetitive inhibition at pH 9 at a temperature of 25°C with Ki values of 0.21±0.03M for glucose and 0.11±0.04M for maltose. The pH-dependence of the inhibition type and Ki values indicate that the ionizing groups of WBA influence drastically the interaction with these carbohydrates. This evidence enables us to consider temperature and pH in the WBA-catalyzed hydrolysis to manipulate the inhibition by end-product, maltose, and even by glucose.

No abstract

Fluorescence of wheat β-amylase (WBA) was quenched by the interaction with maltose or glucose, which are competitive inhibitors of WBA, suggesting that the states of tryptophan and tyrosine residues could be changed by the interaction. The fluorescence emitted by excitation at 280 and 295 nm was titrated by changing the concentrations of maltose and glucose. The dissociation constant (Kd) values of the WBA-maltose and WBA-glucose complexes were determined to be 0.20 ± 0.12 M for maltose and 0.36 ± 0.11 M for glucose at 25°C, pH 5.4. Maltose exhibited additional binding mode at higher concentration with a distinct Kd value (1.5 ± 0.4 M). The Kd values at various temperatures and pHs are in agreement with the inhibitor constant (Ki) values previously reported. The negative standard enthalpy changes (ΔH°) of the WBA association with glucose and maltose indicate that the associations are exothermic. The association constant (Ka) and ΔG° values of the maltose and glucose binding to WBA decreased slightly with increasing temperature from 25°C to 45°C but not dependent on pH change (pH 3.0, 5.4 and 9.0). Fluorescence of WBA could be used as a structural probe to examine the inhibitory interaction with the products of starch hydrolysis.

Fermented foods were most prepared products for their benefits of health such as medicinal, therapeutic and probiotic effects. These effects were due to potential probiotic microorganisms such as lactic acid bacteria and yeasts. The purpose of this study was to evaluate the probiotic characteristics of yeasts isolated from Ethiopian traditionally fermented foods and dairy products. The isolates identified and subjected to analyses to determine their probiotic properties. From the selected isolates ten were found to be resistant and showed good growth at pH 2, 2.5and 3for 24h and were able to grow at both 25, 37 and 45°C but best growth was found at body temperature 370C. The three isolates namely Y66, Y82 andY36 showed maximum growth at pH 2.5 with corresponding mean OD value of 1.45, 1.40 and 1.09. From the finding insolate Y77 and Y82 performed well at pH 2.5 and 3 compared to other isolates. The three isolates GB48, Y77 and Y82 shown highest growth rate with mean OD630nm value of 2.25, 1.85 and 1.78 respectively at 370C. Isolates were also investigated for bile salt tolerance, cholesterol assimilation, co aggregation and antioxidant abilities. IsolateY76 and Y82 were found to be with highest bile salt tolerant and cholesterol assimilation of 46.56, 56.20% and 96.11, 92.11% of assimilation respectively. The two isolates Y77 and Y82 also showed good survival rate of 44.59 and 36.56% in gastrointestinal fluid and antioxidant scavenging ability of 44.59 and 36.00% respectively. Among these isolates Y82, Y76 and Y77 have been found to bear with promising desirable probiotic potentials properties.

Ruminant animals lack enzymes to break down fibrous feeds but they harbor microorganisms capable of degrading their feeds. Rumen microbes are affected by feed substrates. The purpose of this study was to evaluate rumen microbial changes as the function of varying supplementary feeds. Two protein supplements (cottonseed cake and tree lucerne) and two energy supplements (wheat bran and molasses) were offered to rumen fistulated oxen of two groups varying in age. The supplements vary mainly in protein and fibre contents. Switch over design was used in the experiment and the oxen were switched to another supplement after one week to avoid the carryover effect. Microbial populations, correlations with feed nutrient composition and enzyme assays in each case were studied and JMP 5.1 computer software was used for the analysis. Both the bacterial and fungal populations were the highest in oxen supplemented with cottonseed cake (10.7x1011cfu/ml bacteria & 10.8x105cfu/ml fungi) in both young and older oxen (7.4x1010cfu/ml bacteria & 7x105cfu/ml fungi), respectively. The total microbial populations were higher in younger groups supplemented with similar supplement than the older groups of oxen and the least microbial count was observed in those supplemented with tree lucerne (Chamaecytisus palmensis). The enzyme activities were also compared and showed significant variations and linear relation with the nutrient compositions of the feeds. A supplement rich in both fibre and protein supported dynamic rumen microbial population and is very important for the production of quality animal products.