Browsing by Author "Maingi, John M."

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    Molecular Characterization and Diversity of Bacteria Isolated from Fish and Fish Products Retailed in Kenyan Markets
    (Hindawi, 2022-07-18) Kyule, Domitila Ndinda; Maingi, John M.; Njeru, Ezekiel Mugendi; Nyamache, Anthony Kebira
    Fish products are highly vulnerable to microbial contamination due to their soft tissues, making them perishable and harmful to consumers. The clinical and subclinical infections reported by fish consumers are mainly associated with pathogenic microorganisms in fish products. Therefore, this study aimed at establishing the molecular profiles and diversity of the bacterial isolates from fish and fish products obtained from Kirinyaga County markets in Kenya. A total of 660 samples were randomly sampled in six Kirinyaga County markets and transported to Kenyatta University for bacterial isolation. The fish skin surface was cut using a sterile knife and blended in buffered peptone water. The blended product was serially diluted and plated on nutrient agar. After 24 hours, the bacteria cultures were subcultured to obtain pure bacterial isolates. The pure isolates were grouped and characterized based on their morphology and biochemical characteristics. One representative of each group was selected for bacterial DNA extraction. The 16S rRNA gene was amplified using the 27F and 1492R primers, and the obtained PCR product was subjected to Sanger-based sequencing using the same primers. Morphological characterization yielded 54 morpho groups. Phylogenetic analysis revealed diverse bacterial strains, including Escherichia coli, Salmonella enterica, Citrobacter freundii, Bacillus sp. and Alcaligenes faecalis. Bacillus sp. was the most dominant group, as compared to other isolates in the study. The study, therefore, revealed diverse bacterial strains from the fish products. This high microbial diversity calls for heightened surveillance to prevent possible foodborne disease outbreaks.
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    Morphological Assessment and Effectiveness of Indigenous Rhizobia Isolates that Nodulate P. vulgaris in Water Hyacinth Compost Testing Field in Lake Victoria Basin
    (SCIENCEDOMAIN, 2013-12-05) Muthini, Morris; Maingi, John M.; Muoma, John O.; Amoding, Alice; Mukaminega, Dative; Osoro, Newton; Mgutu, Allan; Ombori, Omwoyo
    Aims: The study was aimed at isolating, identifying and assessing the effectiveness of indigenous rhizobia nodulating P. vulgaris in Lake Victoria Basin (LVB).Study Design: Randomized complete block design.Place and Duration of Study: Soil and nodule samples were collected from Kisumu (Kenya); Kabanyolo (Uganda) and Nyabarongo (Rwanda). Field experiments: Kisumu (Kenya). Lab and greenhouse experiments: Department of Plant and Microbial Sciences Kenyatta University (Kenya) and Makerere University (Uganda). Research was carried out between January 2012 and April 2013.Methodology: Rhizobia were isolated from nodules obtained from P. vulgaris (rose coco variety) plants planted in the LVB water hyacinth compost trial fields and whole soil trapping experiments in the greenhouse using soil obtained from the LVB. The isolates were characterized using morphological features. Isolates from each group were used in authentication using the infection technique.Results: One hundred and twenty eight isolates were obtained from the trapping experiments and placed into nine groups based on their morphological characteristics. Four hundred and seventy two isolates were obtained from the nodules of the P. vulgaris grown in soils amended with water hyacinth compost and were placed into sixteen groups. The isolates varied in their morphological characteristics. There was a significant difference in the infectiveness and effectiveness of the representative rhizobia isolates.Conclusion: The studies revealed that rhizobia isolates from Lake Victoria are different morphologically. Authentication experiments, confirmed that the majority of the isolates were rhizobia due to their ability to infect the host plant P. vulgaris. All representative isolates varied in their ability to infect and fix nitrogen. Isolates that are more effective compared to the commercial Rhizobium leguminosarum biovar phaseolistrain 446 were isolated in this study. The effective indigenous rhizobia have therefore the potential of being sources of inocula for P. vulgaris.
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    Performance of Mwitemania Bean Under the Influence of Nitrogen-Fixing Rhizobium Inoculant, Water Hyacinth Composts and DAP Fertilizer in a Field Infested with Aphis fabae and Colletotrichum lindemuthianum
    (Springer, 2021-11-10) Naluyange, Victoria; Ochieno, Dennis M. W.; Wandahwa, Philip; Maingi, John M.; Ombori, Omwoyo; Mukaminega, Dative; Amoding, Alice; Odendo, Martins; Muoma, John V. O.
    The production of beans in the Lake Victoria basin of East Africa has been declining while the water hyacinth has been invasively spreading in the lake. These are understood to be effects of nitrogen (N) loss among other nutrients from land and their deposition into the lake resulting in eutrophication. To mitigate these problems, bean seeds are being inoculated with Rhizobium inoculants to fix nitrogen as an alternative to fertilizers in maintaining soil nitrogen; while water hyacinth biomass is processed into composts to enrich soil fertility. The present study evaluates the growth and yield of Rhizobium inoculated seeds when grown without fertilizer (control), with diammonium phosphate fertilizer (DAP), or supplied with water hyacinth composts containing cattle manure culture (H + CMC) or effective microbes (H + EM). Infestations by the black bean aphid Aphis fabae and the anthracnose disease infestations caused by Colletotrichum lindemuthianum on these bean plants were also assessed. Root nodulation was found to be higher in Rhizobium inoculated plants grown with H + EM (20 nodules) and those without fertilizer (19 nodules) when compared to controls (7 nodules). In DAP treated plants, the germination percentage was low, growth rate slow, with few root nodules, flowers and pods, resulting in reduced yield. The differences between treatments for anthracnose disease incidence were similar to those of root nodules; while aphid populations did not vary between the treatments. The results of the present study do not offer a reliable basis for the application of water hyacinth composts and Rhizobium in improving the yields of Mwitemania beans. This is very likely because the soils were relatively fertile; N-fixation by Rhizobium is more efficient in unfertile soils. Better results may be achieved in soils of low fertility especially those deficient in nitrogen, hence conducive for N-fixation.
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    Response of Common Bean (Phaseolus vulgaris L.) Cultivars to Water Hyacinth (Eichhornia crassipes [Mart.] Solms) Compost in Kisumu, Kenya along the Lake Victoria Basin
    (Journal of Experimental Agriculture International, 2018-09-06) Kawaka, Fanuel; Ombori, Omwoyo; Maingi, John M.; Amoding, Alice; Mukaminega, Dative; Muoma, John
    Aims: This study aimed at enhancing common bean production among the small holder farmers along the Lake Victoria basin, Kenya through the use of water hyacinth compost.Study Design: Randomized Complete Block Design with a split-plot structure with three replications. The bean cultivars formed the main plots while fertilizers formed the sub-plots.Place and Duration of Study: Field trials were conducted on small holder farms in Kisumu, Lake Victoria basin during the short and long rains in 2012/2013.Methodology: Fresh water hyacinth weeds were cut into smaller pieces and left to completely dry in the sun and allowed to decompose naturally for 45 days. The treatments consisted of control (no fertilizer), water hyacinth compost and diammonium phosphate (DAP) fertilizer (DAP). The fertilizers were applied at the rate of 46 kg ha-1 of DAP or 8 T ha-1 of compost along the rows and thoroughly mixed within the top 15 cm of soil to avoid direct contact with the seeds or the rhizobia inocula.Results: Water hyacinth compost significantly (P<0.05) increased nodulation and improved yield while diammonium phosphate also enhanced yield but suppressed nodulation of the beans. Other agronomic characteristics such as plant height, number of flowers and pods of beans were not significantly (P > 0.05) influenced with the application of either compost or diammonium phosphate.Conclusion: Application of water hyacinth compost has the potential for use as an alternative to expensive inorganic nitrogenous fertilizers in restoring soil fertility and improving bean crop productivity in Kenya.