Browsing by Author "O. Ogolla, Fredrick"

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Assessment Of Wild Rodents Endoparasites In Kirimiri Forest In Embu County, Kenya
(International Journal of Advanced Research and Publications, 2019-05) O. Ogolla, Fredrick; Omondi, Clifton; Odhiambo, Christopher
Rodents are reservoirs and hosts of zoonotic diseases. Rodents’ pathogenic parasites can be introduced onto soils, water supplies, vegetables and fruits thus playing significant role in human infection. Though studies on rodents and their parasites are necessary to understand and manage zoonotic disease cycle, knowledge gap of endoparasite composition of wild rodents that interact with domestic animals and human still exists in Kenya. This study was carried out to determine the prevalence of rodents’ endoparasites in Kirimiri forest, Embu County in Kenya between January and May 2016. Wild rats were caught by laying traps in 100 m x 100 m grid of 50 Sherman and 50 victor traps. Rodents’ morphometric data was used for their identification. Necropsy was performed for gastrointestinal tract (GIT) and endoparasites extracted, counted and prevalence determined. Three species of rats totaling to 355 rats comprising of 199 males and 156 females were captured and identified. A total of 533 endoparasites extracted. Rate of endoparasite prevalence was significantly higher in Rattus spp a peri-domestic rodent than forest rodents’ species (χ= 57.791, P = < 0.05). Asyphalia obvelata (44.79 %) had higher prevalence while the H. dinimuta had lowest prevalence (6.20 %). Prevalence based on forest patches, GIT and was different. The current study highlights the importance of rodents as potential vectors for intestinal parasitic infections.
Characterization of Antibioticproducing Actinomycetes Isolated from River Tana and Lake Elementaita in Kenya
(Asian Journal of Research in Biochemistry, 2023-08-01) O. Shikuku, Bonface; Kiruki, Silas; Kuria, Eric; Mutembei, Martin; O. Ogolla, Fredrick
The rise of antibiotic-resistant bacteria has become a global health concern, necessitating the search for novel sources of antibiotics. Actinomycetes, a group of microorganisms, have been known for their ability to produce bioactive compounds with antimicrobial properties. This study aimed to isolate, identify, and characterize antibiotic-producing Actinomycetes from River Tana and Lake Elementaita. Samples were collected from the study sites, and Actinomycetes were isolated using serial dilution and spread plate techniques. The isolates were characterized based on their morphological and biochemical properties. Furthermore, their antibacterial activity against Escherichia coli, Staphylococcus aureus, and Salmonella typhi was evaluated using the agar well diffusion method. The zones of inhibition were measured (mm), and analysis was done to compare the activity of the isolates using Kruskal Wallis test and medians compared using Wilcoxon with Bonferroni correction at alpha = 0.05 in SAS version 9.4. Analysis of DNA sequences was done using the BLAST program and a phylogenetic tree was constructed using MEGA X version 11. Biochemical tests revealed positive results for catalase, indole, oxidase, and citrate utilization, while coagulase and methyl red tests were negative. In terms of antibacterial activity, 54.5% of the isolates showed activity against E. coli, 45.5% against S. aureus, and 45.5% against S. typhi. Isolate LEL2201 had significant (p < 0.05) higher zone of inhibition against S. aureus (inhibition zone of 25.0mm), while isolate RT2201 exhibited the highest activity against E. coli and S. typhi (inhibition zone of 8.5 mm and 8.6 mm, respectively). Molecular characterization through 16S rRNA gene sequencing identified the isolates as belonging to the Actinobacterium order. Phylogenetic analysis revealed their similarity to known Actinomycetes species including Actinomycetales bacterium, Streptomyces intermedius and Streptomyces flavomacrosporus from various countries. The findings of this study demonstrate the presence of antibiotic-producing Actinomycetes in River Tana and Lake Elementaita. Thus, further investigations are warranted to identify and characterize the specific antibacterial compounds produced by these isolates.
Effect of pH, Carbon and Nitrogen Sources on Antibiotic Production by Actinomycetes Isolates from River Tana and Lake Elementaita, Kenya
(Asian Journal of Research in Biochemistry, 2023-08-04) O. Shikuku, Bonface; Kiruki, Silas; Kuria, Eric; Mayo, Domnic; O. Ogolla, Fredrick
The escalating concern over antibiotic resistance and its profound impact on public health have underscored the urgent need to explore alternative reservoirs of antimicrobial agents. In this regard, Actinomycetes have emerged as a compelling area of investigation due to their remarkable capacity to produce bioactive compounds. Therefore, this study sought to investigate the influence of pH and various carbon and nitrogen sources on the antibacterial activity of Actinomycetes isolates collected from Lake Elementaita and River Tana. By examining the effects of these factors, we aimed to gain insights into the optimization of growth conditions and nutrient availability to enhance the production of bioactive compounds with potent antibacterial properties. The Actinomycetes isolates used in this study were from Lake Elementaita and River Tana, known for their diverse ecological characteristics and potential as sources of bioactive compounds. The isolates were subjected to morphological, biochemical, and molecular techniques to ensure accurate identification. To assess the antibacterial activity of the Actinomycetes isolates, they were tested against E. coli using the agar well diffusion method. The independent variables examined in this study were pH levels (4, 7, and 9) as well as different carbon sources (fructose and sucrose) and nitrogen sources (urea and sodium nitrate). The diameter of the inhibition zones served as the dependent variable. The data collected on the effects of pH and nutrients on the inhibition zones of Actinomycetes isolates were subjected to statistical analysis. One-way ANOVA was performed to assess significant differences in antibacterial activity among the isolates under different carbon and nitrogen preference. Mean values were compared using the LSD test at a significance level (α) of 0.05. Furthermore, the Kruskal-Wallis test was utilized to analyze the pH preferences of the Actinomycetes isolates at a significance level (α) of 0.05. The results showed that pH significantly influenced the bioactivity of the Actinomycetes isolates, with pH 7 exhibiting the highest inhibition zones against E. coli. The isolates displayed varied antibacterial activities depending on the carbon and nitrogen sources provided. Sucrose was the most preferred carbon source, followed by fructose, while urea was the preferred nitrogen source, followed by sodium nitrate. The study concluded that pH and nutrient availability play crucial roles in determining the antibacterial activity of Actinomycetes isolates. Other than contributing to our in-depth understanding of the factors influencing the antimicrobial potential of Actinomycetes, the results of this study highlight the importance of optimizing growth conditions and nutrient availability to enhance the production of bioactive compounds with potent antibacterial properties. Further investigations and exploration of Actinomycetes from diverse environments are recommended to discover new bioactive molecules for combating antibiotic resistance.
Incidence and Severity of Turcicum Leaf Blight Caused by Exserohilum turcicum (pass.) Leonard and Suggs) on Sorghum Populations in Different Regions of Tharaka Nithi County, Kenya
(Journal of Scientific and Engineering Research, 2019) O. Ogolla, Fredrick; M. Muraya, Moses; O. Onyango, Benson; ; ;
Sorghum (Sorghum bicolor (L.) Moench) is a drought tolerant food crop preferred by subsistence farmers in dry areas which experience low annual rainfall. However, Turcicum Leaf Blight (TLB) caused by Exserohilum turcicum has threatened sorghum production in the world. New sorghum varieties have been introduced into the Kenyan production systems, including the drier parts of Tharaka Nithi County to boost yield and thus meet the increased demands for food and as a raw material by brewing industries. Nonetheless, challenges due to infection by TLB have negatively impacted on sorghum production resulting from damaged photosynthetic leaves. This study was conducted to determine the incidence and severity of TLB on sorghum populations indifferent regions of Tharaka Nithi County. Sorghum farms in eleven villages for the study were selected by multistage random sampling. The study was conducted between the month of January and June 2018. Data analysis was done by SAS software version 9.3 and significantly different means separated using LSD test at 5% probability level. There was statistically significant difference in the severity and incidence of E. Turcicum leaf blight on sorghum population from different regions in Tharaka Nithi County (P<0.05). Disease TLB occurred in all the villages surveyed though at different frequencies. The disease incidence was higher at Kithaga, and Nkairini recording 74.45% and 55.93%. and lowest at Gatuntu and Gituntu both recorded the disease incidences 12.22%. Thus, farmers should be educated on sorghum TLB management for increased sorghum production and higher income to farmers.
Pathogenicity of Alternaria Species Causing Tomato Blight in AgroEcological Zones of Kirinyaga County in Kenya
(Asian Journal of Advances in Agricultural Research, 2023-04-22) O. Ogolla, Fredrick; M. Muraya, Moses; O. Onyango, Benson; ; ;
Tomato (Lycopersicon esculentum Mill) is a highly consumed and produced vegetable crop with an annual global production of over 185 million tonnes. High consumption and production are due to its nutritional and health benefits. However, tomato production is characterized by inconsistent quality and yields, partly emanating from biotic constraints attributed to fungal foliar diseases. In Kirinyaga County, where tomato production is a significant source of livelihood, knowledge gaps exist regarding the identity of Alternaria species causing tomato blight in different Agro-ecological zones (AEZs) and the susceptibility of locally grown tomato varieties to the Alternaria pathogens. To address these gaps, we conducted a study to determine the characteristics of an Alternaria pathogen isolated from tomato leaves from different AEZs and assess the susceptibility level of some tomato varieties grown in Kirinyaga County. Pathogen characterization was done using phenotypic and molecular approaches, and the susceptibility assay was evaluated by artificial inoculation. The molecular characterization involved BLASTIN analysis of Sanger sequenced DNA nucleotide amplicons, and the use of NCBI databases. The susceptibility assay was carried out in the greenhouse using a completely randomized design. Data on the fungal conidial lengths (µm) and the susceptibility (%) of tomato varieties to fungal isolates were subjected to Analysis of Variance (ANOVA) with significance means separated using LSD at α = 0.05. The morphologies of the pathogens differed significantly (p <0.05). Molecular characterization implicated Alternaria solani, Alternaria cerealis, Alternaria arborescens, and Alternaria alternate in causing tomato blight. Tomato varieties differed in their susceptibility to Alternaria pathogens (p < 0.05). Kilele F1 (73.84%), and Terminator F1 (56.48%) were the most and least susceptible tomato varieties, respectively. Thus, Terminator F1 can serve as a source for the genetic improvement of tomato varieties in the Kirinyaga patho-system. Our study provides valuable information on the identification of Alternaria species causing tomato blight in different AEZs in Kirinyaga County and the susceptibility of locally grown tomato varieties to infection by Alternaria pathogen isolates. The findings can aid in the development of effective disease management strategies and the genetic improvement of tomato varieties in the area.
Variation in Temperature and Nutrient Source Influence the Growth of Exserohilum Turcicum Mycelia Isolated from Sorghum
(Journal of Scientific and Engineering Research, 2019) O. Ogolla, Fredrick; M. Muraya, Moses; O. Onyango, Benson
Turcicum leaf blight (TLB) caused by the fungus Exserohilum turcicum is a serious threat to production of maize and sorghum, since it damages photosynthetic leaves. Growth and development of E. turcicum pathogen is influenced by factors such as light, temperature, dew period, plant age and inoculums concentration. Tharaka Nithi county in Eastern Kenya where sorghum is actively grown has heterogenous climatic and edaphic conditions. It is currently unclear if variations in temperature and media type may influence growth, development and virulence of Exserohilum turcicum. Thus, this study was carried out to investigate the effect of media type and different temperature variations on the growth and development of mycelia of E. turcicum isolates from Tharaka Nithi county in Kenya. Results showed that the effect of temperature was significantly differences for development of E. turcicum (Pr < 0.05) mycelia. Media type had significant effect on growth of E. turcicum isolates (p<0.05). Corn meal agar with mean of 4.233 cm was the best growth media followed by Malt extract agar at 3.3200 cm, while the most preferential (p<0.05) temperature for mycelia growth was 30 oC. The study recommends in cooperation of wider environmental factors in future studies involving TLB pathogen from Tharaka Nithi county.