Faculty of Science

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    A Comparative study of the optical properties of Nematic Homologues
    (Egerton University, 1998) Rop, Ronald Kiprono
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    Analysis of flavor and molecular diversity of Kenyan Lablab Bean (Lablab Purpureus (L.) Sweet) accessions
    (Egerton University, 2010-12) Kimani, Esther Nyambura
    The legume species Lablab purpureus L. Sweet grows in most tropical environments. It is used as a cover crop and green manure and provides a high–protein food for humans and livestock feed. The study was carried out to analyse flavour components and molecular diversity of Kenyan lablab accessions. Twenty four accessions from the National genebank and farmers were evaluated for odour and bitter taste intensities using sensory tests. Analysis of cyanogenic glycosides was carried out using the picrate method and volatile compounds were isolated and separated using gas chromatography. The genetic diversity of 50 accessions was studied using Amplified fragment length polymorphism (AFLP) markers. The sensory evaluations showed significant (p<0.05) differences for the bitter taste but none for odour. Accession 10706 and 13096 exhibited the highest and lowest means respectively for both bitter and odour taste. The levels of cyanogenic glycosides were not different for the 24 accessions, but significant (p<0.05) differences were observed in the volatile compounds isolated from the accessions with upto 89% similarity of the accessions. Two hundred and sixty two volatile compounds were identified using literature databases. The molecular study revealed a total of 180 polymorphic bands. The overall mean expected heterozygosity (He) for all the populations was 0.189. The Eastern population had the highest He of 0.297. The plot of the first and second principal coordinates for cluster analysis revealed an overlap of the accessions forming a tight cluster, with the exception of four; namely Mwingi-3 and 12000 from Eastern population, 12187R3 and 10706R1 from Coast and Rift Valley populations. The Unweighted pair group using mathematical arithmetic averages (UPGMA) cluster analysis generated from the distance matrix revealed three major groups. Group 1 had accessions 10706R1 and Mwingi-3, group 2 had accessions 12187R3 and 12000, while group 3 had the rest of the accessions. The low diversity revealed from these results may be due to the narrow genetic base for breeding stocks, and exchange of germplasm across the country. Results obtained from this study will be of great help in lablab accession management by ensuring maximization of exploitation of this vital resource as well as in developing breeding strategies for Lablab purpureus.
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    An analysis of marketing of African indigenous vegetables among Agro-pastoral Maasai of Narok and Kajiado Counties
    (Egerton University, 2015-03) Riziki, Magogo Juma
    The Maasai of Narok and Kajiado counties have started embracing agro-pastoralism as a livelihood diversification strategy. Among the crop enterprises they have incorporated are African Indigenous Vegetables in abid to take advantage of their resilience to the changing environment. However, for African Indigenous Vegetables to be beneficial, it requires efficient marketing. A marketing analysis of African Indigenous Vegetables was conducted in Narok and Kajiado counties to determine the most preferred marketing outlets, the characteristics of the different actors in the marketing and the marketing margins of key marketing outlets of the African Indigenous Vegetables. The study also established the factors influencing the choice of African Indigenous Vegetables marketing outlets among the agro-pastoral Maasai. Data was collected from 200 respondents using structured questionnaires. Purposive sampling method was used to select the sub counties and locations while a list from the extension offices was obtained and systematic sampling technique used to select the households for the data collection. Descriptive statistics were used to determine the most preferred marketing outlets as well as the characteristics of the different actors in the marketing of African Indigenous Vegetables. Market margin analysis was used to determine the marketing margins of key marketing outlets while a multinomial logistic regression model was used to establish the factors influencing the choice of marketing outlets of African Indigenous Vegetables. The descriptive results indicated that the most preferred marketing outlet in the studied areas is the local open-air market (55%) and the identified marketing actors have no specialization in terms of training in their marketing roles. Females were found to be predominant in marketing OF African Indigenous Vegetables. The marketing margin of African Indigenous Vegetables varied between the key marketing outlets due to price and marketing cost variation. The results for marketing margin also show that the local open air market is the most profitable marketing outlet for the commonly grown African Indigenous Vegetables. The results of the logistic regression model revealed that the choice of marketing outlet of the sampled agro-pastoral Maasai is influenced by quantity of African Indigenous Vegetables sold, distance to the agricultural market, sex of the household, education level, household size, levels of value addition, farming experience in agro-pastoralism, off-farm income and marketing costs. In view of the research findings, it is imperative to enhance African Indigenous Vegetables marketing in the studied areas to contribute to improved livelihoods among the agro-pastoral Maasai communities.
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    Analysis of Selected Toxic Heavy Metals and Pesticide Residues in Catha Edulis from Selected Regions in Meru County, Kenya
    (Egerton University, 2024-09) Oyugi, Albert Morang’a
    Heavy metal and pesticide pollutions on environmental matrices and their potential human toxicity have attracted considerable attention worldwide in recent years. The desire to increase food production to satisfy the ever rising population has resulted in the use of potentially toxic pesticides and fertilisers. The application of these chemicals in modern farming technologies is a source for potentially toxic heavy metals and pesticide residue levels in human consumables such as foodstuffs, which may ultimately trigger adverse health effects. Accordingly, this study focused on the concentration profiles of cadmium (Cd), lead (Pb), chromium (Cr), iron (Fe), nickel (Ni), and copper (Cu) and pesticide residues in 11 khat (Catha edulis) samples randomly sourced from 11 farms within regions of Meru County, Kenya. These analyses are meant to evaluate any associated human health risks through comparison with the World Health Organisation/ Food and Agriculture Organisation (WHO/FAO) safe limits. Human health risk assessment was done using target hazard quotient (THQ) and health index (HI). Inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis gave results of heavy metal concentrations (mg/kg) in dry khat samples as follows; Cd (7.81 ± 1.56), Cr (15.98 ± 2.22) and Pb (32.35 ± 9.95), indicating all was above the acceptable WHO/FAO limits. The levels of Ni, Cu and Fe heavy metals were below permissible limits and may benefit important human biological functions. The Pb and Cd THQ values and the HI of all investigated heavy metals in the khat samples exceeded the threshold value of 1.0. This suggests that the excessive consumption of Meru khat-based products, poses a potential health risk to the consumers. Besides, the gas chromatograph-mass spectrometry (GC-MS) results showed the detection and identification of pyrethroid and organophosphate pesticides representing 54.5% pesticide contamination prevalence rate of the sample size. The Ultraviolet-Visible (UV-Vis) quantification results revealed that acephate and cypermethrin residue levels in khat samples were below maximum residue limits (MRLs) thus, there is no acephate and cypermethrin pesticide contamination reported from this study. Consequently, Meru khat farmers should regularly be educated on safe post-harvest practices to protect consumers. Therefore, the results of this work are important in sensitizing khat farmers that the use of agro-chemicals should significantly be minimized or avoided on farms and encourage on alternative farming practices that do not potentially increase potentially toxic heavy metals and residues in khat. Regular monitoring and evaluation of pesticide residues and heavy metals in khat products is necessary to ensure public and environmental health.
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    Analysis of total Hla-G Levels and its isoforms in placental malaria
    (Egerton University, 2008-08) Muriira, Geoffrey Karau
    The present study examined the total, membrane bound and soluble HLA-G in infected and uninfected placentas using quantitative real time PCR, ELISA and immunohistochemistry. The total HLA-G transcripts differed significantly (p = 0.009) between infected and uninfected primigravidae. The membrane bound HLA-G transcripts were significantly more abundant than the soluble HLA-G in infected placentas (p = 0.04) in all mothers. At the protein level infected placentas had higher mean levels of soluble HLA-G than uninfected and naïve sera. Soluble HLA-G concentration differed significantly between infected and uninfected primigravidae with a p of 0.001. Immunohistochemistry study demonstrated intense staining of HLA-G in infected placentas, with localization of membrane bound HLA-G protein in the syncytiotrophoblasts and near immune cells, when compared to uninfected placentas. Soluble HLA-G localized in the intervillous spaces and in the lumen of the stroma of forming fetal blood vessels. Soluble HLAG concentrations in infected primigravidae and secundagravidae were negatively correlated to birth weight. Conversely, the concentration in infected multigravidae was positively correlated to birth weight and maternal age. Maternal age and the concentration of soluble HLA-G correlated negatively in all parities in a physiological pregnancy. However, in infected primigravidae and multigravidae the maternal age and soluble HLA-G correlated positively. The findings of this study indicate that there are high levels of HLA-G in infected placentas from all parities compared to the uninfected placentas. However, the levels of HLA-G in infected primigravidae are significantly higher than in uninfected with p value of 0.001. These results shows that HLAG is involved in mediating anti-inflammatory response in P. falciparum infected placentas. The study findings suggest that interventions during pregnancy malaria should promote expression of HLA-G in the placenta to check down the effects of the inflammatory infiltrates in the P. falciparum infected placenta.
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    Analysis of Tsetse Fly (Diptera: Glossinidae) blood meals using mitochondrial cytochrome genes for vertebrate host identification
    (Egerton University, 2009-06) Ngambi, Catherine Nyawira
    Information on the vertebrate hosts of blood feeding vectors forms a useful decision-making tool in the planning of tsetse fly control and eradication operations. The objective of this study was to investigate the utility of mitochondrial Cytochrome c oxidase I and Cytochrome b gene sequences in the identification of tsetse fly blood meals in order to provide a basis for more rational control of trypanosomosis in East Africa. Blood fed Glossina swynnertoni were sampled from the Serengeti (Tanzania) and G. pallidipes were from Nguruman and Busia in Kenya. Tsetse blood meal analysis was carried out by amplification and sequencing, to score polymorphisms in the partial COI and Cytb genes with diagnostic value. Sequences obtained were used to query the BOLD and GenBank databases, and the percent identities used to identify hosts. Hosts identified from blood fed G. swynnertoni collected in Serengeti ecosystem, included twenty five buffaloes, nine had fed on giraffes, three on warthogs and other three had fed on elephants and one on spotted hyena. In Nguruman, the analyzed G. pallidipes were found to have obtained their blood meals from different hosts which included six elephants, five warthogs, a buffalo and a baboon. Only cattle blood was detected in flies caught in Busia in western Kenya. Regarding the hosts identified in the different sampling sites, insecticides on cattle will form an integral part of a control strategy for trypanosomosis in Busia, while different approaches, for example traps and targets are needed for Serengeti and Nguruman ecosystems, where wildlife abound and are the major component of the tsetse fly food source. These results demonstrate the feasibility of the COI and Cytb gene sequences for the identification of the vertebrate hosts of tsetse fly species.
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    Analysis of wave exciting forces on a floating rectangular barge at zero forward speed
    (Egerton University, 2015-11) Ngina, Purity Muthoni
    Surface waves have significant effects on the hydrodynamics of offshore bodies or structures on a fluid of finite depth. Wind, moving vessels, seismic disturbances of shallow sea floors (tsunamis) and the gravitational disturbances of the sun and the moon are factors responsible for generation of waves. Their influence is very crucial in engineering analysis, design, and optimization. Many researchers in the field of hydrodynamics have analyzed the effect that surface waves have on bodies with cylindrical cross section. However, little has been done on structures that have rectangular cross-section especially on incompressible fluids. This study, therefore, focused on the analysis of wave motions acting on rectangular offshore structures. The analysis of surface waves characteristics arising from incident wave potential was carried out. This is because the ability to predict offshore structure behavior begins with the study of the nature of ocean in which the vessel operates. These characteristics included: incident wave potential, incident wave elevation, wave velocity and acceleration. The influence of water depth on the wave characteristics was also investigated. Consequently, the wave exciting force resulting from the interaction of such waves on a rectangular floating barge was investigated and analyzed. Boundary integral method together with Green functions in its series form was used to obtain the radiation potentials. These radiation potentials were used to solve diffraction and the Froude-Krylov forces for the rectangular floating barge. The forces aforementioned were used in the calculation and the analysis of wave exciting forces. Research finding shows that, the vertical wave acceleration and wave velocity were quite high leading to high vertically induced motions. Acceleration are used in the determination of cargo loads and also in the predictions of sea sickness. Change in water depth was also found to have adverse effect on the wave properties and consequently on the hydrodynamic forces, this was in accordance with shallow water effect. For the surge exciting forces it was evident that the forces increased up to a certain level and then they were radiated away to avoid interference at far field. Moreover heave wave exciting forces was found to be inversely proportional to the wave frequency. Heave motion is the limiting factor in drilling of oil. To reduce the heave forces acting on a body it was observed that there was need to increase the distance of the body from the free surface, that is, the draught length. The results obtained would be of great importance to Kenya in the prospects of exploitation of oil on the southern coast and indeed also in the sand harvesting process that is taking place at the Kenyan coast for the construction of the standard gauge railway.
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    Analytical determination of the effects of phosphatic fertilizers and manure on maize yields in acidic soils in Kisii and Rachuonyo districts.
    (Egerton University, 2009-09) Ademba, Sospeter Jacob
    Maize production in sub-Saharan Africa remains low and the yields are on the decline. This has been attributed to a variety of factors which include soil nutrient depletion and Striga infestation. Soil phosphorous, nitrogen and Striga hermonthica are the major constraints to maize production in Nyanza Province of Kenya. The yields are typical of low input systems ranging below 1.0 t ha-1 against a potential of 5.0 t ha-1 per season. In an attempt to overcome these constraints, field trials were conducted at two on-farm sites, Bototo in Kisii Central district and Kabondo in Rachuonyo district, in Nyanza Province of Kenya. The trials were conducted during the long and short rains seasons in 2007. The study investigated the effects of phosphatic fertilizers and manure on nutrient uptake, nutrient use efficiency, maize yields and soil nutrients content at harvest in both sites. A Randomized Complete Block Design (RCBD) was used with the farmers as replicates. Farmers in Bototo plant H614 variety while those in Kabondo plant H513 maize variety. Plots were top dressed with Calcium Ammonium Nitrate (CAN) fertilizer at a uniform rate of 30 kg N ha.-1 Diammonium Phosphate (DAP), Minjingu Rock Phosphate (MRP) and Triple Super Phosphate (TSP) fertilizers were applied at a rate of 60 kg ha-1 P2O5 and farmyard manure (FYM) at 10 t ha-1. One rate of P (60 kg ha-1 P205) was applied on all the P sources and a no P treatment (check) plus lime only treatment was included in determining the effects due to the applied P in the acidic soils. Complete soil chemical analysis was done in all the plots. To assess the effects of phosphorus fertilizers and manure and estimate the nutrient content and uptake of major nutrients, plant and soil samples were analyzed using standard methods. There were significant (P_ 0.01) crop growth vigor response to the fertilizers and manure due to treatments at both sites. There were significant (P_ 0.01) grain yield, total dry matter yield and harvest index responses to phosphate fertilizers and manure treatments at both sites. Phosphate fertilizers and manure treatments had significant (P_ 0.01) effects on Striga emergence at both sites. Striga emergence correlated weakly with phosphate fertilizers and manure treatments and strongly with grain yield at both sites. Nutrient uptake and removal by the crop significantly (P_ 0.01) increased due to fertilizers and manure application, with a corresponding reduction in the total soil N, P, K, Ca and Mg. Phosphate fertilizers and manure application significantly (P_ 0.01) increased available soil hosphorus, agronomic phosphorus use efficiency (APUE) and physiological phosphorus use efficiency (PPUE) in both sites. The results indicate that phosphate fertilizers and manure applications are essential to improve maize yield, nutrient phosphorus use efficiency and the applied nitrogen reduced the impacts of Striga hermonthica damage to maize yields.
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    Anti-microbial activity, toxicity and chemical characterization of extracts of Indigofera Lupatana Baker F. plant
    (Egerton University, 2010-10) Njeru, Sospeter Ngoci
    Indigofera lupatana Baker F. (locally known as Mugiti) has been used by Mbeere community of Kenya to treat cough, diarrhea, pleurisy and gonorrhea. These and other infectious diseases are a cause of morbidity and mortality in humans and animals. Their effects are further aggravated by drug resistance. There is also increased emergence and re-emergence of infections from previously harmless micro-organisms, as part of nosocomial and opportunistic infections. This calls for search of new drugs that will mitigate these problems. Indigenous plants are promising as a cheap alternative source of new therapeutic agents. Although the use of phytomedicine has been in practice for long, little has been done to evaluate their effectiveness, safety, target organisms and also their chemical characterization. Therefore, the aim of this study was to investigate the antimicrobial activity, toxicity and phytochemical screening of root extracts of Indigofera lupatana Baker F. Powdered sample of I. lupatana Baker F. roots were sequentially extracted using hexane, ethyl acetate, dichloromethane and methanol solvents. The resultant fractions were subjected to anti-bacterial assay, phytochemical tests and brine shrimp toxicity bioassay. The fractions showed the highest activity against Bacillus subtilis (28.5 ± 0.3mm), Staphylococcus aureus (22.6 ± 1.0mm), Bacillus cereus (22.0 ± 0.3mm), Escherichia coli (21.7 ± 0.7mm), Pseudomonas aeruginosa (21.5 ± 0.9mm), Salmonella typhimurium (17.3 ± 0.3mm), Klebsiella pneumonia (15.3 ± 0.4mm) and Proteus mirabilis (12.3 ± 0.5mm). The activity was greater among the Gram positive bacteria than Gram negative bacteria. Activity of the ethyl acetate, dichloromethane and methanol extracts on bacillus cereus species and that of ethyl acetate on P. aeruginosa was similar to the activity of chloramphenicol drug (with P > 0.05). The MIC ranged from between 21.9 to over 750mg/ml. Phytochemical testing revealed presence of Phenolics, Flavonoids, Tannins, Saponins, Terpenoids, Cardiac glycosides, Steroids and Phlobatannins which are responsible for the bioactivity of the sample fractions. All fractions had LC50 value greater than 1000μg/ml which is an indication that they are all non toxic. Therefore Indigofera lupatana Baker F. can be used as an alternative source of new, effective, safe drug(s) against the tested microbes because it demonstrated antibacterial efficacy with no toxicity to brine shrimps.
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    Antidiabetic and wound healing properties of selected Kenyan tea cultivars
    (Egerton University, 2014-03) Chemwotie, Mercy J.
    Diabetes mellitus is a metabolic disorder of multiple etiology, characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action or both. It is associated with significant morbidity and mortality due to cardiovascular complications as a result of imbalance in lipid metabolism. Diabetic foot ulcers (DFUs) are estimated to occur in 15% of all patients with diabetes and precede 84% of all diabetes-related lower leg amputations. Tea is rich in bioactive molecules that may play a role in modulating carbohydrate metabolism and wound healing. The study sought to determine if tea can prevent or reverse metabolic disturbances induced by diabetes, including occurrence of diabetic wounds. Green and black teas were processed from four different cultivars and assayed for their total monomeric anthocyanin content, total polyphenols content, catechin profiles and theaflavin profiles. Teas rich in anthocyanins, epigallocatechin gallate (EGCG), theaflavins (TF) and total polyphenols were chosen for assay in an animal model. An alloxan induced diabetic mouse model was used to study the anti diabetic potential of processed tea. Hyperglycaemia resulting from alloxan administration caused a significant (p<0.05) increase in blood glucose and cholesterol levels as well as low body weights and packed cell volume (PCV). Oral administration of tea helped alleviate these complications. Blood glucose and cholesterol levels were lowered in treated groups compared to controls. PCV levels increased while body weights declined in both diabetic and healthy mice on tea. Anthocyanin rich tea produced more beneficial effects compared to other teas. Wound healing, angiogenesis and wound repair was augmented in anthocyanin treated group when compared to the placebo group, findings well documented by histological investigations. Results of this study demonstrate that hyperglycaemia and deranged carbohydrate metabolism plays a significant role in diabetic complications including artheriosclerosis and delayed wound healing. Moreover, these results demonstrate beneficial effects of tea in wound healing and diabetic complications.
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    Antifungal secondary metabolites from monanthotaxis littoralis with activity against mycotoxigenic fungi from maize
    (Egerton University, 2013-05) Chepkirui, Clara
    This study involved isolation of compounds from the plant Monanthotaxis littoralis, screening and evaluating the activity of the compounds against mycotoxigenic fungi The non volatile secondary metabolites were extracted from the plant using methanol. The methanol extract was suspended in water and extracted with ethyl acetate. Hydro-distillation was used in the extraction of essential oils. Column chromatography and Preparative Thin Layer Chromatography (PTLC) was used in purification of compounds. The solvent system used for separation in this study was 9:1 chloroform ethyl acetate mixture. The isolated compounds were tested for their anti-mould activity against 31 most common and damaging mycotoxigenic moulds from three genera of fungi (Aspergillus, Fusarium and Penicillium) using paper disc diffusion inhibition method. The structural elucidation of the bioactive compounds was carried out by a combination of spectroscopic techniques that include 1 and 2 D high field NMR spectroscopy GC-MS spectroscopy and Mass spectrometry. The oil had eight major compounds which include (-)-Beta-necrodol, (+,-)-tetramisole among others while from the crude extract flavonoids 3, 5-dihydroxy-7-methoxy anthocynidines and 3, 7, 5’- trihydroxy anthocynidines were isolated and compound M whose structure could not be elucidated because of the limitation of the purification methods used was also isolated. The highest activity of the oil was against Penicillium purporogenum, Penicillium islandicum and Aspergillus niger with MIC of 26 mg/ml. These species had inhibition zones of 39.17 mm, 29.60 mm and 15.67 mm respectively. The extent of inhibition of fungal growth was dependent on the concentration of the secondary metabolites. The oil MIC generally ranged from 26 mg/ml and 103 mg/ml. The flavonoids mixture had the highest activity against Aspergillus ochraceus where MIC of 1 mg/ml. In general the non volatile compounds had MIC values ranging from 1 to 4 mg/ml against the mycotoxigenic fungi. These results show that the secondary metabolites isolated from Monathotaxis littoralis have antifungal activities against mycotoxigenic fungi found in foods. Thus these compounds are potential antifungal that can be used in food preservation systems to inhibit the growth of moulds and retard subsequent mycotoxins production.
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    Antimicrobial Phenylpropanoid esters and Sesquiterpene lactones from the leaves of Tarchonanthus camphoratus (asteraceae)
    (Egerton University, 2007-12) Wetungu, Martin Wamalwa
    The plant Tarchonanthus camphoratus belongs to Asteraceae family. Its common name is wild sage or camphor bush. This study was aimed at isolating bioactive phenypropanoid esters and sesquiterpene lactones from the leaves of this plant. A powdered sample of the leaves weighing 500 g was sequentially extracted with of hexane (1.5 L), dichloromethane (1.5 L) and methanol (3 x 1.5 L). The methanolic extract was partitioned between equal volumes (250 ml each) of distilled water. The n-butanol fraction was concentrated under reduced pressure followed by addition of diethyl ether, precipitating 20 g of a dry crude extract. The extract was successively fractionated using hexane, dichloromethane, chloroform, ethyl acetate, acetone, ethanol and methanol yielding 1.6 g, 1.4 g, 1.6 g, 7.0 g, and 1.4 g, 2 g and 4 g respectively of samples soluble in each solvent. Phytochemical and chemical tests were employed in identifying the fractions that contained phenolic compounds and terpenoids. Antimicrobial activity tests of the extracts soluble in various solvents were then performed on Escharichia coli, Staphylococcus aureus, Pseudomonas aeruginos, Klebsiella pneumoniae, Proteus mirabilis, Salmonella typhi, Candida albicans and Bacillus spp. Ethyl acetate and methanol soluble fractions were found to contain phenolics, while hexane, dichloromethane, chloroform and ethyl acetate fractions contained terpenoids. Ethyl acetate fraction was active against E. coli, P. mirabilis, K. pneumoniae, S. typhi, and Bacillus spp while methanol fraction was active against E. coli, K. pneumoniae, S. typhi, and Bacillus spp. The two fractions were combined and subjected to TLC analysis, Column chromatography, HPLC analysis and sephadex LH-20 reversed phase column chromatography, affording three isomers of dicaffeoyl quinic acids: 4, 5- dicaffeoyl quinic acid, 1 (135 mg), 3, 5-dicaffeoyl quinic acid, 2 (125 mg), and 3, 4-dicaffeoylquinic acid, 3 (90 mg) which are known compounds, and a sesquiterpene lactone, 4 (150 mg). Structural elucidation of the compounds was done using IR, MS, 13C- NMR, 1H- NMR, DEPT, 1H-1H COSY, 1H-13C COSY and HMBC techniques.
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    Assesment of the Nutritional Value, Microbial Quality and Sensory Acceptance of Cookies Enriched With Edible Longhorn Grasshoper (Ruspolia Differens Serville) Flours from Different Processing Methods
    (Egerton University, 2023-07) Onyango, Brian Ochieng
    Long-horned grasshopper (Ruspolia differens), an edible insect native to sub-Saharan Africa, is considered a delicacy by some communities in the region and contributes 5-10% of the protein intake. However, its full utilization as food across the different cultural constructs has been hampered by neophobia and disgust occasioned by uncommon food cultural practices, thereby limiting its potential to combat malnutrition in the region. Therefore, there is need to process and hide the insect into modern food products to improve its utilization. The current study investigated the effects of enriching cookies with differently processed R. differens flours on the nutritional composition, digestibility and volatile organic compounds profile, the microbial quality and the sensory acceptance on a 5-point hedonic scale. Blanched, boiled and toasted R. differens-based cookies demonstrated significantly (p<0.05) higher protein (10.90-11.09%) whereas deep-fried R. differens-based cookies exhibited higher fat (25.82%) and energy (514.69 kcal). The levels of essential amino acids; leucine (8.57-8.97 mg/g) and isoleucine (5.56-6.07 mg/g) were significantly (p<0.05) higher in blanched, boiled and toasted R. differens-based cookies than in control and deep-fried R. differens-based cookies. Omega-3 fatty acid, methyl (9Z,12Z,15Z)-octadecatrienoate (0.34-2.12μg/g) was only detected in the cookies integrated with the processed R. differens flours. Methyl hexadecanoate (5.02-10.58μg/g), methyl (9Z)-octadecenoate (11.55-17.20μg/g) and methyl (9Z,12Z)-octadecadienoate (0.19-12.10μg/g) were the dominant fatty acids in the different cookie types. Cookies supplemented with blanched and boiled R. differens exhibited significantly (p<0.05) higher levels of Fe (7.11-7.12 mg/100 g) and Zn (4.17-4.33mg/g). Pleasant aroma compounds; 2E,4E-dodecadienal, pentanal, and octanal, methyl pyrazine, furfurals, benzaldehyde, and 2-pentyl furan, were more pronounced in cookies prepared with boiled, toasted and deep-fried R. differens. The digestibility of R. differens based cookies and control cookies ranged between 71.23-80.41% and 88.22%, respectively. All the cookie types expressed permissible levels of total viable counts (>30 Log cfu/g), Staphylococcus aureus, Salmonella spp and yeast and moulds that are compliant with Kenya Bureau of Standards guidelines on insect-based products. Sensory evaluation suggested that panelists preferred the overall sensory characteristics of control (4.24) and deep-fried R. differens-based cookies (3.97) while lowly rating flavour of blanched R. differens-based cookies (3.17). Summarily, blanched and boiled R. differens-based cookies, expressed excellent nutritional profiles and digestibility. However, blanched R. differens requires masking of the objectionable flavours to enhance consumer preference.
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    An assesment of wetland influence on water quality of river Mereronyi, Kenya.
    (Egerton University, 2009-10) Adhiambo, Susan Clare
    An investigation to assess the influence of a natural wetland in the middle reach of River Mereronyi , Kenya, on the river water quality was carried out between May and June, 2008. The aim of the study was to evaluate the effect of this particular wetland on nutrients (Nitrogen and Phosphorus) and removal and trapping of coliforms (E. coli, total coliforms) in the river water. Water samples were collected weekly using acid washed plastic bottles, while sediment samples were collected using a corer. During every sampling session; temperature, conductivity, Dissolved Oxygen (DO) and pH were measured in situ using Wissensschaftlich-Technische Werkstätten (WTW) microprocessor meters and probes. River discharge was estimated using velocity area method. In the laboratory nutrients; nitrogen and phosphorous were determined using colorimetric methods, while bacteriological analyses were done using pour plate technique and Most Probable Number method. Plant productivity was measured using harvest method, where a 0.25×0.25m quadrat was used to demarcate the plots and plants harvested just above the roots. The concentration of TN and TP in water and sediment was determined using the Kjeldahl digestion method. Data was analyzed using a Statistical Package for Social Sciences (SPSS version 12) where comparison of means of different variables was performed using Analysis of Variance (ANOVA). The relationship between the concentration of different variables in water and sediment samples was analyzed using simple linear regression analysis. Student’s t-test was used to determine the significant difference between selected variables at the wetland inlet and outlet. Water temperature differed significantly between the sites during the study period (t = 2.054, df =54, p < 0.05). Mean river discharge was 4.9 ± 2.2 m3s-1 at the wetland inlet and 6.7 ± 2 m3s-1 at the wetland outlet. The papyrus standing biomass was 21.84 tonnes/ha-1 . There was a significant negative relationship between phosphorus in sediment and that in plants with correlation coefficient of r = - 0.95. A significant positive relationship between total nitrogen in water and in plants with a correlation coefficient of r = 0.91 was also observed in this study. The results showed removal efficiencies by the wetland of 20% for ammonium, 32.7% for nitrate-nitrogen, 61.8% for Soluble Reactive Phosphorus, 57% for total phosphorus and 45.85% for total nitrogen. The highest number of E. coli and total coliforms of 516 MPN/100ml and 390 No/100ml was recorded in a disturbed site 3 (S3) within the wetland. There was reduction of SRP, NO3, TN and NH4 in water between the wetland inlet and wetland outlet. This study recommends that the wetland should be reclaimed by WRMA and NEMA together with the local community.
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    Assessment and molecular characterization of bacterial degraders of hexazinone and 2,4-d herbicides from sugarcane cultivated soils in Nzoia company nucleus estates, Kenya
    (Egerton University, 2018-10) Njue, Reuben Mukundi
    Agrochemicals have been used extensively all over the world for improved food security, industrial development, and poverty reduction. In Western Kenya, herbicides are used to clear weeds in sugarcane growing plantations. Uncontrolled and unregulated use of these herbicides results in contamination of both soils and the associated drainage systems. Their use may have adverse effects such as disruption of microbial, animal and plant diversity in addition to serious effects to human health. Repeated application of the herbicides results in biochemical adaptation of native microbes especially the bacteria, which in turn lead to the enhanced mineralization of the herbicides. Hexazinone and 2,4-dichlorophenoxyacetic acid (2,4-D), are among the most commonly used herbicides in Nzoia sugar cane farms in Western Kenya. The main objective of this study was to isolate and characterize bacterial degraders of hexazinone and 2,4-D from soils collected from Nzoia Sugar Company sugarcane farms in Western Kenya and also to determine their effects on colony forming units (CFUs) and total dehydrogenase (DHA) activity. Isolation was achieved through incubation experiments in mineral salt medium amended with the herbicides. Growth of isolates indicated by turbidity of broths was monitored by optical density measurements, whereas degradation by isolates was determined by quantification of residual herbicides using high performance liquid chromatography. DHA activity analysis was achieved through triphenyl tetrazolium chloride (TTC) based method. The DHA activity showed that 2,4-D had inhibitory effects on total DHA activity while hexazinone had boosting ability for the bacterial growth. Degradation experiments yielded four bacteria strains encoded as N13010H1, N15030H2, N15030H3 and N212H4 which were able to degrade hexazinone and three bacteria degraders encoded as N139D1, N13010D3 and N13010D4 with potential to degrade 2,4-D. Biochemical and molecular characterization showed that, N13010H1 was Bacterium NLAE zl-H322. N15030H2 was identified as Enterobacter sp, N15030H3 as Bacillus cereus while N212H4 was identified as Staphylococcus aureus. All the four isolates had high potential for hexazinone degradation ranging from 57.6 to 82% with N15030H3 showing the highest potential. For 2,4-D degraders, N13010D3 was identified as Serratia marcescens, while N139D1 and N13010D4 were identified as Bacillus sp and Uncultured bacterium clone, respectively. The biodegradation capacity of 2,4-D by the three isolates ranged from 65 to 82% with N13010D3 showing the highest potential. The isolates can be modified and utilized for bioremediation of hexazinone and 2,4-D contaminated soils.
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    Assessment of anti-diabetic properties of the prickly pear cactus in Swiss white mice
    (Egerton University, 2016-11) Mokua, Moraa Peris
    Diabetes mellitus, a metabolic disorder that affects the body’s ability to make or use insulin, has become a major public-health issue globally. This is because of the numerous health problems it causes to humans including: brain damage, heart and renal diseases, circulatory problems, and death. The onset of diabetes mellitus can be due to various causes including genetic that leads mainly to development of Type I diabetes mellitus and the lifestyle of an individual that leads to obesity, a common cause of the Type II diabetes. Various management strategies have been proposed and implemented with the most recent one being the use of extracts of the “prickly pear cactus” Opuntia species, a shrub that grows mainly in semi-arid regions of America, Asia and Africa. The current study aimed at assessing the efficacy of prickly pear cactus cladode extracts in managing diabetes mellitus in diabetic mice and its possible cytotoxic effects. Healthy, adult Swiss white albino male mice weighing 20-30 g were induced with diabetes mellitus using Alloxan (150 mg/kg body weight) administered intra-peritoneally. Prickly pear cactus cladode extracts were administered orally at daily dosages of 0.6 ml and 0.8 ml for pre-determined periods. Fasting blood sugar levels, live body weights and packed cell volume values were monitored during and after termination of feeding on cactus cladode extracts. Liver and kidney tissues were obtained at the end of the experiment and processed for histopathological examination. Alloxan administration caused a 3- to 4-fold increase in blood sugar levels. Diabetic animals treated with cactus cladode extracts showed a decline in blood sugar levels, however, the levels varied with the period of treatment. Diabetic animals treated with cactus cladode extracts for 10 days showed a significant decline in blood sugar levels on the 7th (p=0.012) and 10th (p=0.001) days of feeding on the extracts when compared to the diabetic control animals. Histopathological examination revealed kidneys sections characterised with normal renal architecture. Mild degenerative changes were observed in liver sections of diabetic treated animals. No mortality was reported throughout the experiment. This study has demonstrated that extracts from prickly pear cactus cladode from Kenya have potential in managing blood sugar in alloxan-induced diabetic mice. This study has also demonstrated that cactus cladode extracts minimises the effects of diabetes mellitus on kidneys and liver of diabetic mice.
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    Assessment of ecosystem services in natural wetlands and rice fields in Nyando floodplain, Kenya
    (Egerton University, 2015-04) Ondiek, Risper Ajwang'
    Natural wetlands are crucial ecosystems capable of providing provisioning, regulatory and cultural ecosystem services (ES). However, globally, wetlands are constantly under threats of degradation of their functions and loss or reduction of wetland coverage area, as a result of agricultural intensification due to demands for food production. Natural wetlands in Nyando floodplain are no exception as a result of conversion into rice fields. Such conversions may compromise some of the ecosystem services (ES) (benefits people obtain from ecosystems) in natural wetlands even though rice fields also deliver ES which are important in supporting livelihoods in the area. Therefore, this study aimed to assess ES in Ombeyi natural wetland and rice fields in Nyando floodplain to quantify ES in both systems despite the continuous conversion influence on ES delivery to the community. This study was done for a period of four months running between December 2014 and March 2015. Questionnaire survey and Focus Group Discussion were used to assess provisioning and cultural ecosystem services in Ombeyi natural wetland and rice fields using indicators of measurements for ES such as rice yield, fish quantity, price and aesthetic value among others. The effect of water purification as an ecosystem service was evaluated by analysis of water quality changes through in-situ measurements of physico-chemical parameters, nutrients and sediments content in water from River Ombeyi, Ombeyi natural wetland, rice fields and drainage canals. Water samples were collected twice a month in the inlets and outlets of rice fields and the natural wetland, rice fields’ drainage canals and River Ombeyi for nutrients and total suspended solids (TSS) analysis using standard methods. The results showed that the natural wetland had retention of 19.6% for nitrate-nitrogen, 28.8% for Soluble Reactive Phosphorus, 50% for total phosphorus, 19.1% for total nitrogen and 45.6% for (TSS). In the rice fields the retention of 58.21% for TSS, 36.89% for nitrate, TN 35.72%, SRP 79.16% and TP 60.52% were obtained. The chi-square test showed that rice fields retained more nutrients and sediments compared to the natural wetland (p<0.05) except for ammonium in both systems which were not significantly different (p>0.05). Rice fields were observed to be source of ammonium while natural wetlands acted as transformers. Cultural and provisioning services were graded as low both in the natural wetland and rice fields mainly due to continuous conversion of the natural wetland into rice fields.