DSpace Repository :: Browsing by Author "Maingi, John M."

Browsing by Author "Maingi, John M."

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Agrobiodiversity conservation enhances food security in subsistence‑based farming systems of Eastern Kenya
(BioMed Central, 2016) Mburu, Simon Wambui; Koskey, Gilbert; Kimiti, Jacinta Malia; Ombori, Omwoyo; Maingi, John M.; Njeru, Ezekiel Mugendi
Background: Globally, there is great concern about expanding agricultural activities due to their impact in the conservation of agrobiodiversity. African continent is known for its richness in biodiversity. In Kenya, there is a continuous unabated expansion of agriculture into natural habitats due to demographic and economic pressures posing a significant threat to biodiversity. Therefore, there is a need to study biodiversity loss and its regain through practices in agricultural landscapes. In this study, we assessed the status of agrobiodiversity and its contribution to food security in four agroecological zones of Eastern Kenya. Sixty households were sampled from two selected agroecological zones (upper and lower midland zones) in Embu and Tharaka-Nithi counties. Structured questionnaires and checklists were used to collect the data. Results: Thirty-nine crop species were identified dominated by vegetables, fruits, legumes and cereals with relative densities of 28.8, 20.5, 18.3 and 8.3 %, respectively. Embu Lower Midland and Tharaka-Nithi Lower Midland zones had relatively higher crop species richness of 243 and 240, respectively, and Shannon–Wiener diversity indices (H′) of 3.403 and 3.377, respectively, compared with Embu Upper Midland and Tharaka-Nithi Upper Midland zones with species richness of 229 and 207, respectively, and H′ of 3.298 and 3.204, respectively. Conclusions: Households from lower midland zones with high crop diversity and richness were more food secure compared with those from the Upper Midland zones with low crop diversity and richness. These findings suggest that farm production systems with high agrobiodiversity contributed more toward food security among smallholder farmers in the selected sites. Keywords: Agrobiodiversity, Food security, Biodiversity loss, Smallholder farmers, Kenya
Antimicrobial Resistance Genes in Salmonella and Escherichia Coli Isolates from Chicken Droppings in Nairobi, Kenya
(Cross Mark, 2019) Langata, Lydia Mali; Maingi, John M.; Musonye, Harry Asena; Kiiru, John; Nyamache, Anthony Kebira
Objective: Increase in antimicrobial resistance is a threat to health sector globally. Surveillance on the spread and emergence of antimicrobial resistance is therefore invertible. This study investigated prevalence of Salmonella and Escherichia coli, molecularly characterized their antimicrobial resistance patterns and spread among resistant isolates from chicken droppings. Results: A total of 150 chicken households were selected randomly within Nairobi and fresh chicken droppings collected. Salmonella and Escherichia coli were isolated and antimicrobial susceptibility test carried out. Beta-lactamase genes and class 1 integrons were determined among amoxicillin resistant isolates. Isolates carrying TEM gene were further subjected to (GTG)5 PCR genotyping. Of the analysed samples, 57% and 12% contained Escherichia coli and Salmonella respectively. Most of the isolates were susceptible to the tested antibiotics with exemption of 53% of the isolates that were resistant to amoxicillin. The isolates were detected with TEM (46%), CTX-M (18%) resistance genes and class 1 integrons (25%). The study reveals presence of beta-lactamase genes and class 1 integrons across Salmonella and Escherichia coli isolates from droppings of reared chicken. Therefore, the wide distribution of chicken and their fecal waste is likely to increase development of antibiotic resistance.
Assessment of Physicochemical Changes during Composting Rice Straw with Chicken and Donkey Manure
(Springer Science + Business Media, 2019) Karanja, Anncarol W.; Njeru, Ezekiel M.; Maingi, John M.
Purpose Traditional methods of composting are limited in timely production of good-quality compost due to recalcitrant nature of materials of plant origin. This study focused on evaluating the use chicken and donkey manure as starter cultures to biostimulate bioconversion of rice straw into bioorganic fertilizer. Use of starter cultures would enhance composting as a strategy for rice straw management to enhance soil fertilization and reduce environmental pollution. Methods In this study, chicken manure and donkey manure were used as starter cultures to enhance bioconversion of recalcitrant and abundant rice straw in Mwea, the main rice-producing area in Kenya. Treatments of the study included rice straw co-composted with chicken manure (T1), rice straw co-composted with donkey manure (T2) and a control (T0) consisting of un-treated rice straw. Temperature, pH and electrical conductivity (EC) were monitored throughout the composting period. Resultant compost types were characterized in respect to their macro-nutrient concentrations, cation exchange capacity, pH and heavy metal content. Results Levels of temperature, pH and EC among the treatments of the study revealed signifcant diferences at 5% level of confdence using Tukey’s test. The three resultant compost types obtained were also physicochemically diferent as revealed by analysis of variance of cation exchange capacity, phosphorus, nitrogen and carbon content. Conclusion Results indicated that use of chicken and donkey manure signifcantly improved the composting process and the quality of resultant compost.
Assessment of Physicochemical Changes During Composting Rice Straw With Chicken and Donkey Manure
(Springer, 2019) Karanja, Anncarol W.; Njeru, Ezekiel M.; Maingi, John M.
Purpose Traditional methods of composting are limited in timely production of good-quality compost due to recalcitrant nature of materials of plant origin. This study focused on evaluating the use chicken and donkey manure as starter cultures to biostimulate bioconversion of rice straw into bioorganic fertilizer. Use of starter cultures would enhance composting as a strategy for rice straw management to enhance soil fertilization and reduce environmental pollution. Methods In this study, chicken manure and donkey manure were used as starter cultures to enhance bioconversion of recalcitrant and abundant rice straw in Mwea, the main rice-producing area in Kenya. Treatments of the study included rice straw co-composted with chicken manure (T1), rice straw co-composted with donkey manure (T2) and a control (T0) consisting of un-treated rice straw. Temperature, pH and electrical conductivity (EC) were monitored throughout the composting period. Resultant compost types were characterized in respect to their macro-nutrient concentrations, cation exchange capacity, pH and heavy metal content. Results Levels of temperature, pH and EC among the treatments of the study revealed signifcant diferences at 5% level of confdence using Tukey’s test. The three resultant compost types obtained were also physicochemically diferent as revealed by analysis of variance of cation exchange capacity, phosphorus, nitrogen and carbon content. Conclusion Results indicated that use of chicken and donkey manure signifcantly improved the composting process and the quality of resultant compost.
Belowground influence of rhizobium inoculant and water hyacinth composts on yellow bean infested by aphis fabae and colletotrichum lindemuthianum under field conditions
(Canadian Center of Science and Education, 2016) Naluyange, Victoria; Ochieno, Dennis M. W.; Wandahwa, Philip; Odendo, Martins; Maingi, John M.; Amoding, Alice; Ombori, Omwoyo; Mukaminega, Dative; Muoma, John
Rhizobium inoculant has been developed for bean production in Lake Victoria basin. Two types of compost have been developed, water hyacinth compost with cattle manure culture (H+CMC) or with effective microbes (H+EM). Influence of Rhizobium and composts on Aphis fabae and Colletotrichum lindemuthianum were investigated in the field. Rhizobium and hyacinth composts increased nodulation (×2 to 5); while Aphis fabae population increased (×2) on Rhizobium-inoculated plants with H+EM. Incidence of C. lindemuthianum was high in Rhizobium-inoculated plants. Plants that received diammonium phosphate (DAP) fertilizer had few nodules, reduced germination, slow growth and low yields. In conclusion, the water hyacinth composts contain beneficial microbes that promote root nodulation by Rhizobium, which is necessary for nitrogen fixation, while enhancing tolerance to aboveground infestations by A. fabae and C. lindemuthianum. We raise questions on our results to stimulate research, considering that bean breeding programs in Africa have mainly focused on microbial pathogens, and not insect pests.
Differential Response of Promiscuous Soybean to Local Diversity of Indigenous and Commercial Bradyrhizobium Inoculation under Contrasting Agroclimatic Sones
(Springer Nature, 2020) Mburu, Simon Wambui; Koskey, Gilbert; Njeru, Ezekiel Mugendi; Ombori, Omwoyo; Maingi, John M.; Kimiti, Jacinta Malia
Promiscuous soybeans are grain legumes that nodulate with diverse strains of indigenous Bradyrhizobium and play a significant role in biological nitrogen fixation through symbiosis. However, experiments on the potential use of promiscuous soybean varieties have recorded very low nodulation and poor nitrogen fixation probably due to ineffective native Bradyrhizobium isolates. Experiments were designed to investigate symbiotic nitrogen fixation of two promiscuous soybean varieties (SB8 and SB126) with indigenous Bradyrhizobium isolates in contrasting agroclimatic zones through greenhouse and field experiments. Inoculation of soybeans in the greenhouse had a significant (p < 0.001) effect on shoot and nodule dry weight. The best performing indigenous isolates RI9 and RI4 from the greenhouse study outperformed the commercial inoculant (Biofix) in symbiotic effectiveness with 119.17%, 142.35% and 101.01%, respectively. Inoculation in the field experiments showed a significant (p < 0.0001) increase in shoot dry weight and grain yield of promiscuous soybean. Agroclimatic zones showed significant (p < 0.0001) variability in above ground biomass of soybean due to inoculation. Despite the apparent promiscuity of the soybean varieties used, the response in nodulation suggests the cultivars grown under contrasting agroclimatic zones have a preference to specific Bradyrhizobium isolates.
Effects of water hyacinth (Eichhornia crassipes [mart.] solms) compost on growth and yield of common beans (Phaseolus vulgaris) in Lake Victoria Basin
(European International Journal of Science and Technology, 2014) Osoro, Newton O.; Kawaka, Fanuel; Naluyange, Victoria; Ombori, Omwoyo; Muoma, John O.; Amoding, Alice; Mukaminega, Dative; Muthini, Morris; Maingi, John M.
Water hyacinth (Eichhornia crassipes) has become a problem in water bodies all over the world. Various methods have been used to eradicate the macrophyte but with little success. The weed has high content of the nutrients absorbed from its environment. Hence there is need to assess the potential of utilizing the weed for commercial purposes such as compost to substitute the use of inorganic fertilizers which contributes to climate change. The objective of the study was to evaluate the effects of water hyacinth compost prepared using different treatments on the growth and yield of common beans. Field experiments were carried out at Otonglo Division in Kisumu County (Kenya) and greenhouse experiments were carried out at Kenyatta University. The water hyacinth compost was prepared using effective microorganisms (EM) solution, cattle manure and molasses separately as starter cultures for composting. The effect of compost on crop production was assessed by applying the compost to common beans (Rose coco) on separate growth pots in the greenhouse and plots in the field respectively. The treatments applied included compost prepared with EM (8.837 g/pot), compost prepared with cattle manure (8.837 g/pot), compost prepared with molasses (8.837g/pot), diammonium phosphate (DAP) fertilizer (70.7 mg N/pot), inoculum (beans treated with Rhizobium leguminosarum strain 446) and control. 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 were laid out in a Randomized Complete Block Design with six treatments and three replications for each treatment in the greenhouse and five treatments replicated four times in three farmers’ fields. Application of water hyacinth compost and DAP significantly (p ≤ 0.05) influenced the growth of common beans. The best performance of Rose coco plants in terms of dry weight, root dry weight, number of nodules per plant, nodule dry weight and root collar diameter was recorded when the soil was amended with water hyacinth compost prepared with EM (WHE). Yield parameters such as 100 seed weight, grain yield and stover weight were significantly (p < 0.05) influenced when the soil was amended with various treatments. It can therefore be concluded that 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 common beans production.
Endophytic Bacillus aerophilus from the Leaves of Azadirachta indica as a Potential Biocontrol against Staphylococcus aureus
(Journal of Advances in Microbiology, 2023) Mwendwa, Peter Kasyula; Karanja, Anncarol W.; Maingi, John M.
The study entailed isolation and identification of Bacillus aerophilus in the leaves of young Azadirachta indica plants, establishing the antimicrobial activity of the endophyte against Staphylococcus aureus, and screening for phytochemicals. The study investigated the potential of the endophytic Bacillus aerophilus in pathogen inhibition and phytochemical screening for bioactive compounds produced by the endophyte that can be used in drug development. The research contributes to the wider scientific goal of curbing rising cases of antibiotic resistance. Place and Duration of Study: Sample: collected from Kanyonyoo in Kitui County, between August 2022 and June 2023. Methodology: The bacteria were aseptically isolated and sub-cultured on nutrient agar. For identification, the bacteria underwent biochemical tests and molecular characterization. The 16S rRNA region was amplified and sequenced using universal primers 27F and 1492R. Bacterial isolate K1L003 was identified as Bacillus aerophilus. For antimicrobial testing, the agar disk diffusion method was used against pathogenic Staphylococcus aureus on Mueller Hinton Agar plates (MHA). The controls were doxycycline and vancomycin. Results: The endophytic isolate only inhibited Staphylococcus aureus (P < .001), with an inhibition mean similar to doxycycline (26 mm), against the pathogen. The endophytic isolate produced terpenoids, saponins, alkaloids, and flavonoids. Conclusion: Endophytic Bacillus aerophilus has better antimicrobial inhibition potential than vancomycin, against Staphylococcus aureus and produces diverse bioactive secondary metabolites. The endophyte has the potential to produce compounds that are useful in treating drug-resistant Staphylococcal infections.
Phytochemical and Antioxidant Screening of Seed Extracts of Kenyan Custard Apple (Annona squamosa)
(2017) Mwihia, Stephen K.; Ngugi, Mathew P.; Maingi, John M.
Medicinal plants have been the mainstay of traditional herbal medicine amongst rural dwellers worldwide since antiquity for their preventive and curative properties. Investigation of plants for phytochemicals and medicinal activities is imperative for the discovery of prospective novel molecules for medicinal use. This current analysis was aimed at screening the seed extracts of Annona squamosa for the presence of phytochemicals and their antioxidant activities. Extraction of the active components was through organic solvents; methanol, dichloromethane and methanol: dichloromethane blend in Soxhlet extractor and concentrated in a rotary evaporator. Investigation of phytochemicals was through standard qualitative screening procedures while antioxidant activities of the extract were evaluated through the radical scavenging effect of DPPH, H2O2 and the FRAP assay. Methanol was the most effective solvent in capturing phytochemicals including tannins, alkaloids, flavonoids, fixed oils and phenols. Dichloromethane captured only alkaloids and fixed oils. The antioxidant data obtained was assayed against that of the standard (Ascorbic acid). The methanolic extract was found to be the most potent extract with highest antioxidant activities followed by methanol: dichloromethane blend while dichloromethane portrayed the least potency. The highest DPPH radical scavenging was at 500mg/ml, while for H2O2 was at 1mg/ml while the highest FRAP activity was at 1mg/ml. Methanolic extracts were the most potent while dichloromethane extracts showed the least DPPH and H2O2 radical scavenging activities. Phenols appear have significantly contributed towards the antioxidant activity of the methanolic extracts and the alkaloids in dichloromethane extracts. Most of the inedible parts of commonly consumed fruits have not been studied for their antioxidant activity but the current assay demonstrates that seeds may be a promising source of antioxidants. This study shows that the seed extracts of Annona squamosa may be utilised therapeutically in the management of oxidative stress related disorders. Keywords:Annona squamosa, Phytochemical, Antioxidant, Radical Scavenging, diphenyl-picrylhydrazyl (DPPH), Hydrogen Peroxide (H2O2) and Ferrous Reducing Antioxidant Power (FRAP)
Potential of Native Rhizobia in Enhancing Nitrogen Fixation and Yields of Climbing Beans (Phaseolus vulgaris L.) in Contrasting Environments of Eastern Kenya
(Frontiers Media, 2017) Koskey, Gilbert; Mburu, Simon W.; Njeru, Ezekiel M.; Kimiti, Jacinta M.; Ombori, Omwoyo; Maingi, John M.
Climbing bean (Phaseolus vulgaris L.) production in Kenya is greatly undermined by low soil fertility, especially in agriculturally prolific areas. The use of effective native rhizobia inoculants to promote nitrogen fixation could be beneficial in climbing bean production. In this study, we carried out greenhouse and field experiments to evaluate symbiotic efficiency, compare the effect of native rhizobia and commercial inoculant on nodulation, growth and yield parameters of mid-altitude climbing bean (MAC 13 and MAC 64) varieties. The greenhouse experiment included nine native rhizobia isolates, a consortium of native isolates, commercial inoculant Biofix, a mixture of native isolates + Biofix, nitrogen treated control and a non-inoculated control. In the field experiments, the treatments included the best effective native rhizobia isolate ELM3, a consortium of native isolates, a commercial inoculant Biofix, a mixture of native isolates + Biofix, and a non-inoculated control. Remarkably, four native rhizobia isolates ELM3, ELM4, ELM5, and ELM8 showed higher symbiotic efficiencies compared to the Biofix. Interestingly, there was no significant difference in symbiotic efficiency between the two climbing bean varieties. Field results demonstrated a significant improvement in nodule dry weight and seed yields of MAC 13 and MAC 64 climbing bean varieties upon rhizobia inoculation when compared to the non-inoculated controls. Inoculation with ELM3 isolate resulted to the highest seed yield of 4,397.75 kg ha−1 , indicating 89% increase over non-inoculated control (2,334.81 kg ha−1 ) and 30% increase over Biofix (3,698.79 kg ha−1 ). Farm site significantly influenced nodule dry weight and seed yields. This study, therefore, revealed the potential of native rhizobia isolates to enhance delivery of agroecosystem services including nitrogen fixation and bean production. Further characterization and mapping of the native isolates will be imperative in development of effective and affordable commercial inoculants.
Screening of Phytochemicals and Antibacterial Activity of Seed Extracts of Kenyan Sugar Apple (Annona squamosa)
(2017) Mwihia, Stephen K.; Ngugi, Mathew P.; Maingi, John M.; Kamau, James K.; Muhuha, Anne W.
Investigation of plants for phytochemicals and antibacterial effects is essential for discovery of prospective novel complexes for therapeutic use. In the present assay the seed extracts of Annona squamosa were screened for phytochemicals present and antibacterial activities against Salmonella typhi (ATCC 1408), Escherichia coli (ATCC 25922), and Klebsiella pneumonia (ATCC700603) and Shigella flexneri (ATCC 12022). Extraction of the active components was done by the use of organic solvents; methanol, dichloromethane and methanol: dichloromethane blend in soxhlet extractor and concentrated in a rotary evaporator. Phytochemical analysis was done through standard qualitative screening procedures. The antibacterial activities were evaluated through the paper disc diffusion method. Phytochemical analysis exhibited the occurrence of fixed oils, alkaloids, saponins, flavonoids, glycosides, tannins, phenols, steroids and terpenoids which are indicated in antibacterial activity. The methanolic extract was the most efficacious in terms of inhibitory activities, exhibiting a MIC range of 15-31.17mg/ml followed by Methanol: dichloromethane with a MIC range of 16.4-56.57mg/ml while dichloromethane displayed the least bacterial inhibitory activity with a MIC range of 47.50-61.83mg/ml. The antibacterial data obtained was assayed against that of the Ciprofloxacin (reference). Ciprofloxacin activity was significantly higher than all the extracts (p<0.05), though some concentrations exhibited equal activities (p>0.05). The extracts have shown antibacterial effects at their MIC against the microorganisms in the study indicating that with further researches these extracts can be used for treating enteric diseases. Keywords: Annona squamosa, Phytochemical, Antibacterial, Paper disc diffusion method, methanol, dichloromethane extract, enterobacteria.

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