Browsing by Author "Ombori, O."

Now showing 1 - 20 of 36
  • Thumbnail Image
    Item
    Agrobacterium -mediated genetic transformation of selected tropical inbred and hybrid maize ( Zea mays L.) lines
    (Plant Cell Tiss Organ Cult, 2012-10-25) Ombori, O.; Muoma, John Vincent Omondi; Machuka, Jesse
    The study was carried out to evaluate the amenability of tropical inbred and hybrid maize lines, using Agrobacterium mediated transformation technique. Agrobacterium tumefaciens strains EHA101 harbouring apTF102 binary vector, EHA101, AGL1, and LBA4404 harbouring pBECK2000.4 plasmid, LBA4404, GV and EHA105 harbouring pCAMBIA2301 plasmid, and AGL1 harbouring the pSB223 plasmid were used. Delivery of transgenes into plant tissues was assessed using transientb-glucuronidase (gus) activity on the 3rd and 4th day of co-cultivation of the infected Immature Zygotic Embryos (IZEs) and embryogenic callus. Transient gus expression was influenced by the co-cultivation period, maize geno-type and Agrobacterium strain. The expression was highest after the 3rd day of co-culture compared to the 4th day with intense blue staining was detected for IZEs which were infected with Agrobacteriumb strains EHA105 har-bouring pCAMBIA2301 and EHA101 harbouring pTF102 vector. Putative transformants (To) were regenerated from bialaphos resistant callus. Differences were detected on the number of putative transformants regenerated among the maize lines. Polymerase chain reaction (PCR) amplifica-tion of Phosphinothricin acetyltransferase (bar) and gus gene confirmed the transfer of the transgenes into the maize cells. Southern blot hybridization confirmed stable inte-gration of gus into PTL02 maize genome and segregation analysis confirmed the inheritance of the gus. A transfor-mation efficiency of 1.4 % was achieved. This transfor-mation system can be used to introduce genes of interest into tropical maize lines for genetic improvement.
  • Thumbnail Image
    Item
    Agrobacterium Mediated Transformation of Selected Maize Inbred Lines with pPZP200 towards Enhancement of Lysine and Methionine Content
    (IISTE, 2015) Gacheri, P.; Machuka, J.; Ombori, O.; Bukachi, B.
    Maize (Zea mays (L.) is one of the most important cereals used both for human and animal consumption in the world. Despite its importance, maize is not a suitable single source of nutrition because it does not provide the essential amino acids lysine and methionine in sufficient quantities to meet the nutritional needs of humans and other animals. Lysine is a necessary building block for protein in the body while methionine is the body’s primary source of sulphur. Strategies to improve the nutritional quality of maize for high lysine and methionine have involved both genetic engineering (GE) and non-genetic engineering approaches such as marker assisted selection. Breeding is however laborious, lengthy and carries along undesired alleles. The objective of this work was to manipulate maize inbred lines towards enhancement of lysine and methionine content in the endosperms through Agrobacterium mediated transformation. Maize kernels mainly store proteins as α, β, γ and δ zeins. The immature embryos of three tropical maize inbred lines (TL18, CML216 and CML144) and a temperate line (A188) were transformed using Agrobacterium tumefaciens strain EHA101 carrying an expression cassette designed to up-regulate the Z10 protein for methionine enhancement as well as down-regulate the α zein storage protein by RNAi. The T-DNA also contained P-zp22/6 as the promoter and the phosphinothricin acetyltransfarase gene (bar) used for selection of transformed tissue. Putative transformants were tested for presence of the transgene by PCR designed to amplify the P-zp22/6 promoter sequence. Calli survival frequencies were calculated as a percentage number of surviving calli in relation to the total number of embryos infected. These ranged from 2.89 % for TL18 to 9.11 % for A188. This data did not detect any significant difference (p>0.05) among the genotypes on the percentage of calli which survived. Transformation efficiency was calculated as a percentage of the number of PCR positive plants divided by the total number of embryos infected. This ranged from 0% for TL18 to 1.83% for A188. The data suggest the possibility of manipulating storage proteins and regenerating normal transgenic maize with normal kernels. Further work should involve gene expression assays for accumulation of β, γ and δ prolamins in the kernels and southern blot analysis to confirm stable integration and the copy numbers of P-zp22/6 gene in the PCR positive plants
  • Thumbnail Image
    Item
    Agrobacterium mediated transformation of selected maize inbred lines with ppzp200 towards enhancment of lysine and methionine content
    (2012-03-26) Limbua, Purity Gacheri; Machuka, Jesse; Ombori, O.
    Maize (Zea mays (L.) is one of the most important cereals used both for human and animal consumption in the world. Despite its importance, maize is not a suitable single source of nutrition because it does not provide the essential amino acids lysine and methionine in sufficient quantities to meet the nutritional needs of humans and other animals. Lysine is a necessary building block for protein in the body while methionine is the body's primary source of sulphur. Strategies to improve the nutritional quality of maize for high lysine and methionine have involved both genetic engineering (GE) and non-genetic engineering approaches such as marker assisted selection. Breeding is however laborious, lengthy and carries along undesired alleles. The objective of this work was to manipulate maize inbred lines towards enhancement of lysine and methionine content in the endosperms through Agrobacterium mediated transformation. Maize kernels mainly store proteins as a, {3, y and 0 zeins. The immature embryos of three tropical maize inbred lines (TL IS, CML216 and CMLI44) and a temperate line (AlSS) were transformed using Agrobacterium tumejaciens strain EHAI01 carrying an expression cassette designed to upregulate the Z I 0 protein for methionine enhancement as well as down-regulate the a. zein storage protein by RNAi. The T -DNA also contained P-zp22/6 as the promoter and the phosphinothricin acetyltransfarase gene (bar) used for selection of transformed tissue. Putative transformants were tested for presence of the transgene by PCR designed to amplify the P-zp22/6 promoter sequence. Calli survival frequencies were calculated as a percentage number of surviving calli in relation to the total number of embryos infected. These ranged from 2.S9 % forTLIS to 9.11 % for AISS. This data did not detect any significant difference (p>0.05) among the genotypes on the percentage of calli which survived. Transformation efficiency was calculated as a percentage of the number of PCR positive plants divided by the total number of embryos infected. This ranged from 0% for TLIS to I.S3% for AISS. The data suggest the possibility of manipulating storage proteins and regenerating normal transgenic maize with normal kernels. Further work should involve gene expression assays for accumulation of {3, y and 0 prolamins in the kernels and southern blot analysis to confirm stable integration and the copy numbers ofPzp22/6 gene in the PCR positive plants.
  • Thumbnail Image
    Item
    Antibiogram, Metal Tolerance and Plasmid Profiles of Pathogens Isolated from Wastewaters and Sludge of Abattoirs in Nairobi, Kenya
    (2014-02-24) Nyamboya, Rosemary Atieno; Okemo, P. O.; Ombori, O.
    Because of the prevalence of antibiotic resistant pathogenic bacteria, infectious diseases are becoming more difficult and expensive to treat. In Kenya, high levels of flouroquinone resistance of a bacterium, Neisseria gonorrhea have been widely reported. Antimicrobial resistance may be coded on plasmids, mutational events or on transposons. A growing body of evidence indicates that metal tolerance and antibiotic resistance are often found together in many clinical isolates and that metal and antibiotic resistance is closely associated. Besides having clinical consequences, resistant bacteria of animal origin may be the source of determinants of resistance for the possible transfer to human strains. Most of the previous studies have concentrated on clinical isolates from human and animal stools while studies targeting environmental isolates are limited. This study aimed at identifying fecal indicators and pathogens recovered from wastewaters used to clean animal carcass and sludge used as manure, from cattle slaughterhouse in Kayole and the separate sheep and goat slaughterhouses both in Kiamaiko, Nairobi and to determine susceptibility of isolated bacteria against 13 antibiotics and 6 heavy metals, in addition to studying plasmid profiles. Isolation of fecal indicators and pathogens was carried out using standard laboratory methods. Sensitivity to antibiotics was determined by the agar diffusion technique on Mueller-Hinton agar. Heavy metals tolerance was determined by well diffusion and tube dilution methods. Plasmid DNA was isolated using the alkaline lysis method. The fecal bacteria load was found to be 6.2 x 106, 5.3 x 105, 2.5 x 104, 2.9 x 104 and 5.0 x 106 CFU/100 mL for fecal streptococci and 3.4 x 105, 4.1 x 103, 3.0 x 104, 2.7 x 103 and 3.9 x 105 MPN/100 mL for fecal coliforms in cattle wastewater, cattle sludge, goat wastewater, sheep wastewater and a mixture of goat and sheep sludge, respectively. Pearson correlation analysis showed positive correlation between prevalence of fecal streptococci and fecal coliforms (r=0.931 at 0.01 level). Vibrio and Salmonella species were more frequently detected in samples which also showed high incidence of indicator organisms. There was high resistance to lincomycin (90 %), ampicillin (80 %) and methicillin (72.5 %) and low resistance to chloramphenicol (22.5 %). Another potential environmental threat noticed was heavy metal tolerance of the indicator organisms and pathogens to nickel, mercury, copper, zinc, lead and cobalt. Results of the test of toxicity in solid media agreed with those in liquid, however, inhibitory concentrations in solid media were much higher compared to those in liquid. Lead and nickel were the least toxic metals. Mercury was the most toxic component for all bacteria, followed by cobalt and then copper. Among the 40 bacterial isolates studied only 18 (45%) harbored between 1 - 2 kb plasmid DNA bands which ranged in size from 4kb to 10kb. The results showed the dynamics of resistance development in warm blooded animals usually used or consumed by humans. This study provided data on the level and risks of microbiological contamination as well as baseline data for the future assessment and monitoring of pollution levels of wastewaters. With regard to the high contamination level of the wastewaters and sludge with resistant bacteria as revealed in this study, treating of wastewaters and sludge is recommended, before using or discharging them into the environment and also proper use and disposal of antimicrobial agents. The metal-antibiotic double resistance detected in this study call for intervention measures to curb the potential health hazard that heavy metal pollution pose in the environment.
  • Thumbnail Image
    Item
    Antibiotic Resistance of Faecal Bacteria Indicators and Pathogens Isolated from Sludge and Wastewaters of Abattoirs in Nairobi, Kenya
    (Scientific Journals, 2013) Okemo, P. O.; Nyamboya, Rosemary Atieno; Ombori, O.
    Bacterial antibiotic resistance has become a serious problem among pathogenic bacteria and has led to increased concern surrounding environmental risks and potential spread of resistance in microbial species. Besides having clinical consequences, resistant bacteria of animal origin may be the source of determinants of resistance for the possible transfer to human strains. The objectives of the present study were to determine the abundance and distribution of antibiotic and multiple drug resistance among faecal bacteria indicators and pathogens found in wastewaters of animal abattoirs in Nairobi, Kenya. Standard microbiological methods were used to isolate and identify faecal streptococci, faecal coliforms, Vibrio and Salmonella species. Sensitivity to antibiotics was determined by agar diffusion method. The mean intermediary sensitive case (8.1% (±5.6)) was significantly lower (p=0.00) compared to the mean sensitive (41.3% (±23.1)) and mean resistant (50.6% (±22.3)) cases at p<0.05. Isolates showed high resistance to lincomycin (90%), ampicillin (80%), and methicillin (72.5%) and low resistance to chloramphenicol (22.5%). The results provided dynamics of resistance development in warm blooded animals usually consumed by humans. Multiple antibiotic resistance index was >0.2 indicating high risk of exposure to the various antibiotics.
  • Thumbnail Image
    Item
    Compatibility of Rhizobium inoculant and water hyacinth compost formulations in Rosecoco bean and consequences on Aphis fabae and Colletotrichum lindemuthianum infestations.
    (Elsevier, 2014) Ombori, O.; Naluyange, V.; Ochieno, D.M.W.; Maingi, J.M.; Mukaminega, D.; Amoding, A.; Odendo, M.; Okoth, S. A.; Shivoga, W.A.; Muoma, J. V.O.
    The common bean, Phaseolus vulgaris is an important crop for food security and nitrogen fixation through Rhizobium symbiosis. Commercial Rhizobium inoculants are being promoted to fix nitrogen and enhance bean production in the Lake Victoria basin. Rhizobium symbiosis depends on nutrients, especially phosphorus, which is widely applied as diammonium phosphate (DAP) in the Lake Victoria basin. Water hyacinth, Eichornia crassipes (Mart.) Solms-Laubach (Pontederiaceae) is being developed into compost, with perceived benefits of improving crop production and limiting its disastrous spread in Lake Victoria. High nutrient content in water hyacinth compost can stimulate Rhizobium nodulation and nitrogen fixation, consequently improving plant growth and pest resistance. However, it is not yet established whether Rhizobium inoculants and water hyacinth composts are compatible options for plant growth promotion and pest suppression in beans. A field experiment with two trials was conducted to assess the compatibility of commercial Rhizobium inoculant, DAP, cattle farmyard manure (FYM), and four formulations of water hyacinth compost i.e., water hyacinth only (H), with molasses (H+Mol), cattle manure culture (H+CMC) or effective microbes (H+EM). Rhizobium inoculated plants had high number of root nodules when grown with H+CMC and H+EM. Plants were large in size with short development period when grown with the composts, especially H+CMC and H+EM. Those grown with H+EM produced high number of flowers. Rhizobium inoculated plants had high anthracnose incidence than non-inoculated ones when grown with H+CMC. Those grown with H+EM had low anthracnose incidence, but was high in FYM. During flowering, Rhizobium inoculated plants had higher Aphis fabae population than non-inoculated ones when grown in FYM or without fertilizer. Those grown with H+EM had the lowest A. fabae population. Yields in water hyacinth compost were improved, especially for H+CMC in the second trial. DAP treated plants had more flowers and pods having heavy seeds, with low anthracnose and A. fabae infestations; but had low germination rates that reduced the yields. In conclusion, the commercial Rhizobium inoculant is predominantly compatible with water hyacinth compost formulations containing effective microbes and cattle manure culture, which could enhance tolerance of bean plants to aphids and possibly to anthracnose disease. These two water hyacinth compost formulations need further investigation for their potential in enhancing food production and alleviating the water hyacinth problem in the Lake Victoria basin.
  • No Thumbnail Available
    Item
    Cost-effective Nutrient Sources for Tissue Culture of Cassava (Manihot esculenta Crantz)
    (Academic Journals, 2012-08) Mwangi, M.; Ogero, K.O.; Gitonga, N.M.; Ombori, O.; Ngugi, M.
    Application of tissue culture technology is constrained by high costs making seedlings unaffordable. The objective of this study was to evaluate the possibility of using locally available fertilizers as alternative nutrient sources for cassava micropropagation. A Low Cost Medium (LCM) whereby the conventional sources of four Murashige and Skoog (MS) macronutrients had been replaced with locally available fertilizers was developed. Stanes Iodized Microfood® from Osho Chemical Industries in Nairobi was used as the alternative source of micronutrients. Modified conventional MS medium was used as the control. Both media were supplemented with 30 g/l of table sugar and 3 g/l of gelrite. Two cassava varieties, Muchericheri and KME 1 were regenerated on the two media. Node, leaf and root formation patterns plus plant height were determined and compared. A reduction of 95.50% in nutrient cost was achieved. The two cassava varieties had a significantly (p < 0.05) higher number of nodes on the conventional medium compared to LCM. There were no differences in node formation by the two varieties on the low cost medium during both initiation and multiplication. KME 1 produced significantly more leaves on the LCM compared to Muchericheri during both initiation and multiplication. Acclimatization of plantlets was successful; hence, this protocol can be adopted in cassava regeneration.
  • Thumbnail Image
    Item
    Ecological Factors Influencing Distribution Patterns of Three Aristida Species and their Associated Species in Kifuko Ranch, Laikipia County, Kenya
    (2013-12-17) Mbaluka, Kimeru John; Ombori, O.; Vorontsova, M.; Nderitu, G. G.
    Livingorganisms are influenced by several sets of environmental factors. These factors are either biotic (living) or abiotic (non-living) and are categorised as climatic, topographic, edaphic and biotic. For any species to survive in a given location, it must evolutionarily adapt to the area's habitat environmental factors so as to outperform other species intruding into its niche. To understand and answer many questions emanating from plant species adaptation dynamics in relation to a habitat's prevailing environmental conditions, this planned study intends to investigate the possible ecological factors behind the distribution patterns for the two Aristida life forms (annual and perennial) at Kifuku Ranch, Laikipia County, Kenya. Findings of this study will assist in range management and more so in coming up with proper management systems for sustainable pasture resource utilization in the region. In achieving its objectives, the study will assess, record and document spatial distribution patterns for Aristida annual and perennial species as well as to determine the likely ecological factors that influence localized distribution pattern of the group's two life forms. It will also investigate likely associations for either annual or perennial life forms in the group with other plants species. This study will cover an area of ca. three thousand (3000) hectares and in the coverage area, four transects each measuring 3 km long, will be established. Floral and ecological data will be collected at the four transects and in (IxI) m ten randomly picked microsites. Samples and data to be collected will include: soil samples, topographic data, and microhabitat data including; presence of boulders/stones, termites hills, site depressions, percentage of shade in the plots and plots' aspect, floral distribution in the points, and area's past and current anthropogenic activities. Collected data will be described using descriptive and inferential statistics. Canonical Correspondence Analysis (CCA) will be used to examine the occurrence of annuals and perennials of genus Aristida in relationship to specific ecological factors at a variety of sites. Isolation for spatial distribution patterns of Aristida annual and perennial species and associations of either annual or perennial life forms in the group with other plants species will be done by Cluster analysis (CA). These analyses will be executed using the STATISTICA software program
  • Thumbnail Image
    Item
    Effects of water hyacinth (Eichhornia crassipes [mart.] solms) compost on growth and yield parameters of maize (Zea mays).
    (SCIENCEDOMAIN International, 2013-11-18) Osoro, N.; Muoma, J.O.; Amoding, A.; Mukaminega, D.; Muthini, M.; Ombori, O.; Maingi, J.M.
    Aims: To evaluate the effects of water hyacinth compost prepared with various cultures on growth and yield parameters of maize. Study Design: Randomized Complete Block Design. Place and Duration of Study: Field experiments were carried out at Otonglo Division in Kisumu County and greenhouse trials were carried out at Kenyatta University from November 2011 to August 2012. Methodology: The water hyacinth compost was prepared using effective microorganisms (EM) solution, cow manure and molasses separately as starter cultures for composting. The compost was applied on maize (H513) on separate growth pots in the greenhouse and plots in the field. The treatments applied included compost prepared with EM (8.84 g/pot), compost prepared with cow manure (8.84 g/pot), compost prepared with molasses (8.84g/pot), diammonium phosphate (DAP) fertilizer (70.7 mg N/pot) and control (without fertilizer). For the field experiments, water hyacinth compost was applied at a rate of 5000 kg ha-1 and DAP at 40 kg N/ha. The experiments had five treatments and three replications for each treatment in the greenhouse and four treatments replicated four times in three farmers’ fields. Results: Application of water hyacinth compost and DAP significantly influenced positively (P ≤ 0.05) the growth attributes of maize. Among the various treatments of the compost, water hyacinth compost prepared with EM (WHE) performed better in most parameters evaluated including plant height, shoot dry weight, root dry weight and root collar diameter. Yield parameters such as 100 seed weight and grain yield were not significantly (p > 0.05) influenced by various treatments. Conclusion: Water hyacinth which is locally available and in large quantities (especially in lake Victoria) can be composted to prepare organic fertilizers and effectively used as an organic soil amendment to restore soil and increase maize production.
  • Thumbnail Image
    Item
    Efficient plant regeneration of selected kenyan sweetpotato (Ipomoea batatas (L.) Lam.) cultivars through somatic embryogenesis
    (2016) Mbinda, W.; Anami, S.; Ombori, O.; Dixelius, C.; Oduor, Richard
    Sweetpotato is an important food crop in the world as well as in Kenya. Various fungal and viral diseases are major constraints in its production and are currently threatening the sweetpotato production in sub-Saharan Africa. Genetic engineering offers significant potential for the crop’s genetic improvement. However, this is limited by the low efficiency and strong genotype dependency in tissue culture. This study aimed to establish an efficient somatic embryogenesis and plant regeneration system using shoot apical meristem explants of sweetpotato. Three sweetpotato cultivars that are widely grown in Kenya; KSP36, Kemb36 and Mweu mutheke along with an exotic model cultivar Jewel were evaluated. The maximum somatic embryogenic induction, at 96.72%, was obtained from explants cultured on Linsmaier and Skoog salts and vitamins medium supplemented with 0.5 mg/l dichlorophenoxyacetic acid and 0.2 mg/l zeatin riboside. The highest number of shoot induction (33) was observed after transfer of embryonic callus to embryo maturation medium supplemented with 2 mg/l abscisic acid. Significant differences were observed between cultivars for somatic embryogenesis and plant regeneration. Jewel showed the best response, while Mweu mutheke was the least responsive under the culture conditions tested in this study. Regenerated plants were successfully rooted and grown to maturity after hardening in soil in the greenhouse. Such a robust, successful and efficient system possesses the potential to become an important tool for crop improvement and functional studies of genes in sweetpotato.
  • Thumbnail Image
    Item
    Enhancing access to disease-free sweetpotato planting materials through low cost tissue culture for food security and poverty alleviation in Eastern Africa
    (ABIC, 2014) Ogero, K.O.; Mwangi, M.; Gitonga, N.M.; Ombori, O.; Ngugi, M.
    Sweetpotato is a major food staple in Eastern Africa because of its ease of cultivation and ability to thrive in marginal areas. However, limited supply of disease-free planting materials constrains production. Tissue culture technology offers a solution to this but it is very costly. Hence, it is necessary to have low cost options for production of clean planting materials. In this study, two low cost media were developed and used to regenerate two sweetpotato varieties, KEMB 36 and Tainung. In the first low cost medium (LCM 1), 2g/l of Easygro® vegetative fertilizer (27:10:16 (N: P: K) + microelements) supplemented with table sugar (30g/l) and agar (9g/l) was used as an alternative source for the conventional Murashige and Skoog (MS) basal salts. In the second medium (LCM 2), the conventional sources of four MS macronutrients were substituted individually with locally available fertilizers while Stanes Iodized Microfood® was used as the low cost source of micronutrients. Conventional MS medium (CM) supplemented with 30g/l of table sugar and 3g/l of gelrite was used as the control. The numbers of nodes, roots, leaves and plant height were recorded at 14 days interval for a period of six weeks. A cost reduction of 96.9% in nutrient sources was realized with LCM 1 while LCM 2 led to cost reduction of 94.4%. KEMB 36 had a regeneration index of 7.8 nodes per plantlet on LCM 2 during initiation while Tainung had a mean of 3.8 nodes per plantlet after the sixth week of culture. The two sweet potato varieties recorded regeneration indices of 3.3-7.1 nodes per plantlet during multiplication. This study has shown that it is possible to reduce the cost of sweetpotato tissue culture by adopting alternative nutrient sources
  • Thumbnail Image
    Item
    Farmers’ awareness level on the effect of parthenium weed (Parthenium hysterophorus L.) on agricultural production and its control in Nyando division, Kenya
    (2014) Mutua, B.M.; Muriithi J. K.; Ombori, O.
    Parthenium hysterophorus L. is an Invasive Alien Species (IAS) that poses threat to agricultural production. The aim of this study was to assess the level of awareness of the effect of parthenium weed on agricultural production and ways through which parthenium is controlled in Nyando division. The research was carried by interviewing 120 farm household heads using purposive sampling technique. This study established that majority of the respondents were unaware that parthenium interfered with milk production (95.0 %), livestock health (78.4 %) and crop yield (53.3 %). On the other hand, 63.3 % respondents were aware that parthenium lowered pasture availability. Physical methods (98.3 %) were majorly used to control parthenium as compared to chemical (1.7 %). This study established that, the ill-effects of parthenium weed on agricultural production were not directly associated to parthenium invasion. Therefore this research recommends that awareness creation campaigns on the adverse effects of parthenium weed on agricultural production and its control should be undertaken urgently. Similarly, integrated control methods should be adopted for effective management of parthenium weed
  • Thumbnail Image
    Item
    From Soil to Soul Crop Productions for Improved African Livelihoods and a Better Environment for Future Generations
    (2011) Ombori, O.
    been initiated to study the effectiveness of macropropagation technology in producing disease free banana seedlings. The study commenced with a survey to identify the important diseases and insect pests of bananas in Eastern and Central Kenya. Pests and pathogens identified were isolated from diseased banana plants. The importance of the isolated organisms in banana health is being determined through pathogenicity tests carried out under greenhouse conditions. Macropropagation nurseries have been established at Kenyatta University and in six sites in farmers' fields representing different agroecological zones, including high, mid and low altitudes. Corms obtained in accordance with established quality assurance protocols have been propagated and the health of the macropropagated banana seedlings is being monitored over a 12 weeks period. The pathogenic organism isolated most commonly is Fusarium oxysporum f. sp. Cubense and radopholus slmllis in some cases. On average 98%of the propaqated comns have produced healthy seedlings that show no symptoms of disease. Less than 1% of the corms propagated rotted in the propagation media (sawdust) due to as yet undetermined causes: A scarcity of healthy corms has been encountered in areas with orchards having high weevil Infestation since most corms do not meet the standard required for macropropagatlon. The results obtained so far' suggest that corms for macropropagation should be selected in orchards where mats are not more than three years old. The information obtained through the study will form a basis of recommending macropropagation technique as an effective method to produce healthy banana seedlings as well as for identifying the key control points for improvement of the macropropagation protocol.
  • Thumbnail Image
    Item
    Heavy metal and associated antibiotic resistance of fecal coliforms, fecal streptococci and pathogens isolated from wastewaters of abattoirs in Nairobi, Kenya
    (Journal of Applied Biosciences, 2013) Atieno, N.R.; Okemo, P. O.; Ombori, O.
    Objective: The pollution of the environment with toxic heavy metals is increasing globally with industrial progress. Microorganisms can be good bio-accumulators of particulate and soluble forms of heavy metals and subsequently resist antibiotics. The present study aimed at assessing the resistance pattern to multiple heavy metals by wastewater bacteria and associated antibiotic resistance. Methodology and results: Standard microbiological methods were used to isolate fecal streptococci, fecal coliforms, Vibrio and Salmonella species from raw animal wastewaters and sludge samples obtained from three abattoirs around Nairobi city. A total of 30 samples were collected. Agar diffusion and tube dilution methods were used to assess the heavy metal resistance while sensitivity to antibiotics was determined by the agar diffusion method. From the 40 isolates obtained, 27 showed multiple resistance to heavy metals. Resistance pattern was as follows; Hg 9 (33.3%), Co 11 (40.7%), Cu 18 (66.7%), Zn 19 (70.4%), Pb 21 (77.8%), and Ni 24 (88.9%). Out of the 27 resistant strains, 5 (18.5%) showed resistance to 5 different metal ions and only 1 (3.7%) showed resistance to two different metal ions. With each of the six metals tested, there was a tendency towards a high frequency of resistance among the isolates to lincomycin (77.8%), tetracycline (70.4%) and ampicillin (66.7%). Conclusion and application of findings: In the present study, heavy metal resistance associated with multiple drug resistance was detected in the bacterial isolates from the wastewater and sludge of the cattle, sheep and goat abattoirs. The high degree of resistance to common antibiotics could be attributed to the contamination of the wastewaters and sludge with heavy metals possibly from animal feeds or drinking waters, leading to co-selection of both metal tolerant and antibiotic resistant microbial species. This requires intervention measures to curb the potential health hazard that heavy metal pollution pose in the environment. The identified heavy metal resistant bacteria could be useful for bioremediation of heavy metals contaminated sewage and wastewaters, but the coupled antibiotic resistance is a worrying phenomenon. Keywords: Heavy metal resistant bacteria, antibiotic resistance, wastewaters, sludge, animals
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    In vitro Micropropagation of Cassava Through Low Cost Tissue Culture
    (2012-09-24) Ombori, O.; Michael, Ngugi; Mwangi, M.; Gitonga, Nkanata Mburugu; Kwame O. Ogero
    Adoption of drought-tolerant crops such as cassava can help alleviate food insecurity in sub-Saharan Africa. However, production is constrained by lack of disease-free planting materials. This can be circumvented through tissue culture but the technology is costly limiting its adoption. There is therefore, need to put in place interventions that will reduce the cost of production hence making tissue culture products affordable. In this research, a low cost protocol for cassava tissue culture was developed and used to regenerate two farmerpreferred cassava varieties, KME 1 and Muchericheri. Easygro® vegetative fertilizer, a locally available foliar feed was used as an alternative source for conventional MS salts. Nodal explants were initiated on a low cost medium containing 2 g/L of Easygro® vegetative fertilizer supplemented with 30 g/L of table sugar and 9 g/L of agar and conventional medium containing MS salts supplemented with 30 g/L of sucrose and 9 g/L of agar. The conventional MS medium was used as the control. The number of leaves, nodes, roots and average plant heights for the resultant plantlets were determined and compared. The variety Muchericheri had a significantly higher regeneration index compared to KME 1 having produced a mean of 6.8 nodes on the low cost medium and 5.6 nodes on the conventional medium compared to KME 1 which had a mean of 5.6 nodes on the low cost medium and 4.5 nodes on the conventional medium. This is an indication that Muchericheri had a better regeneration efficiency compared to KME 1.
  • Thumbnail Image
    Item
    In Vitro Micropropagation of Cassava through Low Cost Tissue Culture
    (2012-05) Mwangi, M.; Ogero, K.O.; Mburugu, G.N.; Ombori, O.; Ngugi, M.
    Adoption of drought-tolerant crops such as cassava can help alleviate food insecurity in sub-Saharan Africa. However, production is constrained by lack of disease-free planting materials. This can be circumvented through tissue culture but the technology is costly limiting its adoption. There is therefore, need to put in place interventions that will reduce the cost of production hence making tissue culture products affordable. In this research, a low cost protocol for cassava tissue culture was developed and used to regenerate two farmerpreferred cassava varieties, KME 1 and Muchericheri. Easygro® vegetative fertilizer, a locally available foliar feed was used as an alternative source for conventional MS salts. Nodal explants were initiated on a low cost medium containing 2 g/L of Easygro® vegetative fertilizer supplemented with 30 g/L of table sugar and 9 g/L of agar and conventional medium containing MS salts supplemented with 30 g/L of sucrose and 9 g/L of agar. The conventional MS medium was used as the control. The number of leaves, nodes, roots and average plant heights for the resultant plantlets were determined and compared. The variety Muchericheri had a significantly higher regeneration index compared to KME 1 having produced a mean of 6.8 nodes on the low cost medium and 5.6 nodes on the conventional medium compared to KME 1 which had a mean of 5.6 nodes on the low cost medium and 4.5 nodes on the conventional medium.
  • Thumbnail Image
    Item
    Isolation of High Antibiotic Resistant Fecal Bacteria Indicators, Salmonella and Vibrio Species from Raw Abattoirs Sewage in Peri-Urban Locations of Nairobi, Kenya
    (Greener Journal of Biological Sciences, 2013-07) Nyamboya, Rosemary Atieno; Okemo, P. O.; Ombori, O.
    The research was conducted to determine indicator organisms’ relationship to specific human pathogens and any presence of antibiotic resistance. Isolationof indicator organisms,Salmonella and Vibrio species was carried out using standard laboratory methods. Sensitivity to antibiotics was determined by the agar diffusion technique. The fecal bacteria load was found to be 6.2 x 106, 5.3 x 105, 2.5 x 104, 2.9 x 104, and 5.0 x 106 CFU/100 mL for fecal streptococci and 3.4 x 105, 4.1 x 103, 3.0 x 104, 2.7 x 103and 3.9 x 105MPN/100 mL for fecal coliforms in cattle wastewater, cattle sludge, goat wastewater, sheep wastewater and a mixture of goat and sheep sludge, respectively.Fecal coliforms showed the highest resistance with a mean resistance frequency of 60.8% (±25.2), followed by Salmonella species at 51.5% (±26.6). Vibrio species showed the lowest mean resistance frequency at 41.6% (±24.8). There was however no significant difference (p=0.859) in resistance among Vibrio, Salmonella, FS and FC isolates at p>0.05.There is a likelihood of slaughterhouse animals and bacteria in the intestines of these animals getting exposed to antibiotics to which the bacteria develop resistance which they can pass to human pathogens and environmental flora.
  • Thumbnail Image
    Item
    Isolation, identification and characterization of microbial contaminants in selected biosafety laboratories in Kenya
    (2014-08-13) Mose, Dennis Nyachae; Okemo, P. O.; Ombori, O.
    Microbial contamination is a constant problem which is often associated with development of all in vitro techniques in biosafety laboratories. The nutrient media in which manipulations are done is a good source of nutrient for microbial growth which results to increased culture mortality. Presence of latent infections can result to variable growth and tissue necrosis. The massive scale under which biotechnology activities are carried out makes the prospect of microbial contamination in the laboratories even though small proportion clearly costly. The objectives of the study will be to assess sources of microbial contaminants in biosafety laboratories, isolate and determine these contaminants based on their morphological and biochemical characteristics, determine resistance bacteria strains and characterize the resistance bacteria strains by molecular techniques. The study will be carried out in the plant tissue culture and plant transformation laboratories at Kenyatta University, KARl Biotechnology Centre and International Livestock Research Institute (ILRI). PDA plates and NA plates will be exposed to air in the laboratories for 30 min after which they will be sealed with parafilm and incubated at 25°C for 72 h and 37°C for 24 - 48 h for PDA and NA respectively. Sterile cotton buds will be used to swab 2 M on laboratory walls, tables and door knobs, lab coats of laboratory staff and biosafety cabinets before and after sterilizing with hypochlorite based disinfectants. The swabs will be inoculated onto the PDA plates and NA plates and then incubated. After visual examination, contaminated plates will be removed from growth rooms. Fungal isolates will be identified using cultural and morphological characters by comparison with standards. Bacterial identification will be carried out using Gram staining, morphology and biochemical reactions in specific media The percentage data of microbes will be transformed using square root method. Statistical analysis will be carried out using ANOVA with GENESTAT Version 6, computer software. Means will be separated using Tukey's Honest Significance Difference at 5% level. RFLP profiles will be scored for absence or presence of bands and the data will be analysed using Gene Alex computer software. Dendograms will be drawn using Neis Genetic Distance with Popgene computer software.
  • Thumbnail Image
    Item
    Low Cost Issue Culture of Selected Cassava(Manihot esculenta Crantz)and Sweet Potato(Ipomoea batatas(l)Lam) Varieties
    (2013-03-21) Ogero, Kwame Okinyi; Mwangi, M.; Mburungu, G. M.; Ombori, O.
    Drought has become a major contributor to food insecurity in sub-Sahara Africa. Drought-tolerant crops such as cassava and sweet potato can help alleviate this situation. However, lack of affordable healthy planting materials of farmer-preferred varieties is a major constraint to sweet potato and cassava production. Conventional tissue culture technology offers an important solution to this but it is very costly, making plantlets out of reach for resource poor farmers. Hence, it is necessary to have low cost options for micropropagation of planting materials. One way of doing this is to substitute the conventional source ofMurashige and Skoog (MS) media salts with alternative sources that are available 10call¥~:'This study sought to compare the cost of regenerating selected cassava and sweet potato "varieties using alternative nutrient sources and the conventional MS nutrient sources. Another objective was to find out if there is any genotypedependent response to regeneration using different media. Two varieties of each crop (KEMB 36 and Tainung for sweet potato and Muchericheri and KME 1 for cassava) were subjected to three treatments with different media composition and replicated nine times. In the first medium (LCM 1), Easygro'" vegetative fertilizer (27:10:16 (N: P: K) + microelements) from Osho Chemical Industries Limited was used as an alternative source for MS basal salts. In the second media (LCM 2), the conventional sources of four MS macronutrients were substituted individually with locally available fertilizers while Stanes Iodized Microfood® was used as the low cost source of micronutrients. Table sugar was used as an alternative source of carbon while the modified conventional MS medium (CM) was used as the control. Growth parameters including numbers of nodes, roots, leaves and plant heigh.t.we.re recorded at 7 and 14 days intervals for cassava and sweet potato, respectively. This was.carried out over a period of five weeks for cassava , and six weeks for sweet potato. The use of LCM 1 for cassava micropropagation led to a reduction of 96.3% in the cost of the ~utrient medium while LCM 2 led to savings of up to 95.5%. For sweet potato a cost reduction of 96.9% was realized with LCM 1 while LCM 2 led to cost reduction of 94.4%. LCM 1 produced better results compared to LCM 2 for cassava regeneration for all the four parameters assessed. The two cassava varieties had regeneration indices of 3-7 nodes per plantlet during initiation and 3.7-6.9 nodes per plantlet during multiplication on all the media. Leaf formation for the two cassava varieties after the sixth week of culture ranged between 2.7 and 7.3 leaves per plantlet on all the media during initiation and 4-7 leaves during multiplication. Muchericheri produced significantly (p:S0.05) higher number of roots on LCM 1. The two cassava varieties had no significant (p2:0.05) differences in root production on LCM 2. Sweet potato varieties produced better results on LCM 2 compared to LCM 1. KEMB 36 had a regeneration index of 7.8 nodes per plantlet on LCM 2 during initiation while Tainung had a mean of 3.8 nodes per plantlet after the sixth week of culture. The two sweet potato varieties recorded regeneration indices of 3.3-7.1 nodes per plantlet during multiplication. The variety KEMB 36 had better leaf production on LCM 2 compared to Tainung and vice versa on LCM 1 during initiation. Acclimatization of cassava was best on vermiculite while for sweet potato it was on a mixture of rice husks and red soil in the ratio 1:2. This study has shown that it is possible to reduce the cost of cassava and sweet potato tissue culture by adopting alternative nutrient sources. However, the differential responses among varieties calls for further investigation.