RP-Department of Biochemistry and Biotechnology

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Leveraging the Complex Interplay between Arbuscular Mycorrhizal Fungi, Seasonal Dynamics, and Genotypic Diversity to Optimize Maize Productivity in Semi-Arid Agroecosystems
(Heliyon, 2024-09) Kipkorir, Koech; Koskey, Gilbert; Njeru, Ezekiel Mugendi; Maingi, John
Maize production under low-input agricultural systems in semi-arid areas of Sub-Saharan Africa faces significant challenges, primarily stemming from the synergistic impacts of climate vari ability and suboptimal agronomic practices. Harnessing soil microbiota, particularly arbuscular mycorrhizal fungi (AMF), represents a pivotal strategy for bolstering low-input systems. However, their functional utility is contingent upon their compatibility with the prevailing environmental conditions and biotic interactions. This study examines the influence of two distinct AMF in oculants on the growth and yield attributes of diverse maize genotypes across varying seasons within semi-arid regions of Kenya. We hypothesized that AMF inoculants exhibit differential adaptability to varying environmental sites and seasons, and their interaction will enhance the provision of key ecosystem services important for maize production. Field experiments were conducted in three semi-arid Counties (Tharaka-Nithi, Embu, and Kitui) during the 2019/2020 cropping seasons. A randomized complete block design with three replications and three treat ments was adopted. Treatments consisted of Rhizatech (a commercial AMF inoculant), a con sortium of AMF isolates (Rhizophagus irregularis and Funneliformis mosseae), and a non-inoculated control. In season one, notable interaction effects were observed for both site × maize genotype (p = 0.0007) and site × AMF inoculation (p < 0.0001), whereby Duma 43 genotype had the highest yield in Embu (11.93 t ha− 1 ) and Kitui (11.76 t ha− 1 ) counties, and Rhizatech and con sortium inoculation consistently led to elevated grain yields across all three genotypes in Kitui, surpassing non-inoculated controls. AMF inoculation notably augmented phosphorus (P) uptake, with Rhizatech demonstrating a 79.7 % increase and consortium showing a 38.7 % increase in shoot P content compared to control plants in season 1. These findings highlight the complex interplay between AMF effectiveness, seasonal variations, and maize diversity. Further research is needed to elucidate the underlying mechanisms driving these seasonal shifts, allowing for opti mized AMF inoculation strategies for improved maize performance under diverse conditions.
Isolation of phages against Streptococcus species in the oral cavity for potential control of dental diseases and associated systemic complications
(Archives of Microbiology, 2024) Chepchumba, Beatrice; Asudi, George. O.; Katana, Japhet; Ngayo, Musa. O.; Khayeli, Juliah Akhwale
Dental infections and systemic complications caused by Streptococcus species in the oral cavity are increasingly exhibiting resistance to commonly used antibiotics, posing a potential threat to global public health. Phage therapy may ofer a supe rior alternative, given that bacteriophages can be easily isolated and rapidly replicate in large numbers. In this study, six Streptococcus species from the oral cavity were characterized. Bacteriophages isolated from wastewater using five of these species as hosts produced plaques ranging from 0.2 to 2.4 mm in size. The phages demonstrated stability within a temperature range of 4 ℃ to 37 ℃. However, at temperatures exceeding 45 ℃, a noticeable reduction in bacteriophage titer was observed. Similarly, the phages showed greater stability within a pH range of 5 to 10. The isolated phages exhibited latency periods ranging from 15 to 20 min and had burst sizes varying from 10 to 200 viral particles. This study supports the potential use of bacteriophages in controlling infections caused by Streptococcus species.
Characterization of Anopheles Funestus Larval Habitats in Kenya: Insights into Malaria Vector Ecology and Control
(European Journal of Ecology, 2023) Omondi, Clifton; Nonoh, James; Ntabo, Regina
The breeding of malaria-spreading vectors such as Anopheles funestus is influenced by various environmental factors that contribute indirectly to the transmission of the Plasmodium parasite. However, there is limited knowledge of larval habitat ecology that hinder prevention and control of mosquito-borne diseases. This study aimed to charac terize larval habitats based on physicochemical and habitat characteristics, considering the abundance of A. funestus. A cross-sectional survey method was used to collect data on the established transects. Physical parameters (water temperature, pH, conductivity, and total dissolved solids) were measured using a 5-in-1 meter probe. Levels of chem ical parameters (sulphate, COD, and BOD) were determined in the laboratory using standard methods. Observations were also made on habitat characteristics (including watercolor, habitat size, and canopy). There was significant effect (P<0.05) of conductivity, pH, sulphate, COD, and BOD on the number of A. funestus larvae. Water samples with a high population of A. funestus larvae were found to have higher conductivity (Me of 470.5), TDS (Me = 235), and pH levels (Me of 6.71). Conversely, water samples with a high population of non-Anopheles funestus larvae were found to have higher COD (Me of 843.20), BOD (Me of 367.2), and SO4 levels (Me of 11.3). A significant correlation (p<0.5) existed between A. funestus larvae and physical water parameters. For instance, Anopheles funestus larvae was high (Me of 36.85) in stagnant water and in semi-permanent water (Me of 47.37). The study demonstrates that both physico chemical and habitat parameters significantly influence the abundance of Anopheles funestus larvae in larval habitats. Parameters such as conductivity, pH, total dissolved solids, sulphate, COD, BOD, watercolor, depth, distance from the homestead, and habitat size were found to be important in determining the presence of A. funestus larvae. Therefore, vector control strategies should include larval source management by targeting rivers and other water bodies to prevent the emergence of Anopheles funestus.
In Vivo Antidiarrheal Effect and Phytochemical Characterization of Plectranthus Barbatus Andrews
(JABET, 2024-01) Ajwang, Emmah Clarice; Ngugi, Mathew Piero; Omwenga, George Isanda; Muruthi, Carolyn Wanjira
Diarrheal infections remain a public health problem. The mainstays of pharmacological therapy for infectious diarrhea include probiotics, antibacterials, and intestinal adsorbents. Nevertheless, these clinical treatments are not devoid of shortcomings including prohibitive costs and adverse effects. Medicinal plants including Plectranthus barbatus (P. barbatus) have folkloric remedies against diarrhea. However, there is paucity of knowledge to scientifically validate the efficacy of P. barbatus on diarrheal infections. The study was undertaken to ascertain antidiarrheal efficacy, bioactive composition, and toxicity profiles of P. barbatus extracts. Antidiarrheal activity and acute toxicity were carried out on Swiss albino mice. Quantitative phytocompound analysis was evaluated using liquid chromatographymass spectrometry (LCMS). Results indicated that P. barbatus extract has antidiarrheal activity whereby it prolonged the start of diarrhea, causing a decline in the occurrence of wet feces and intestinal transit significantly. Additionally, the extract reduced the accumulation of intraluminal fluid resulting in decrease in distension, intestinal overload, and water content in the fecal drops. Also, acute toxicity assay on mice showed that P. barbatus extract was non-toxic at the dosage level of 2000mg/kgbw. In addition, LCMS analysis detected presence of phytocompounds associated with antidiarrheal effects including forskolin, gallic, kaempferol, and quercetin. Findings from the current study offer a scientific validation for the folkloric utilization of P. barbatus in the management of diarrhea.
Serotype Diversity of Foot and Mouth Disease Virus and Molecular Characterization of Serotype O Strains from 2019 and 2020 Outbreaks in Kenya
(Benha Veterinary Medical Journal, 2024) Josiah, Judith M.; Nyamache, Anthony K.; Woldemariyam, Fanos T.; Kariuki, Christopher K.; Paeshuyse, Jan; Kamau, Joseph
Foot and mouth disease (FMD) is a viral infection affecting ruminants and leads to great economic losses. Control and prevention have been a challenge despite the availability of vaccines. The causative agent exists in seven serotypes and is endemic in Kenya, with serotypes O, A, SAT (South African Territory) 1, and SAT 2 and having circulated in the recent past. This study was aimed at determining the current serotype diversity and serotype O variants during the study period. A cross-sectional study was conducted and a total of 267 epithelial samples were collected from animals during the disease outbreaks of 2019 and 2020. Antigen detection was performed using ELISA (Enzyme-Linked Immunosorbed Assay). The negative samples were inoculated on LFBK(Line of Fetal Bovine Kidney) monolayer cells followed by a repeat ELISA for CPE(Cytopathic Effect) positive samples. The partial VP1 gene for serotype O samples was amplified and directly sequenced. The generated sequences were analyzed and compared with the vaccine strain. The prevalence of FMDV was 65.9% (176/267) and serotypes SAT 1, O, SAT 2, and A in the order of decreasing prevalence were circulating. Serotype O viruses analyzed belonged to the EA 2 against the EA 1 vaccine strain in use. For better control of the disease, this study recommends close monitoring of the circulating serotypes and topotypes, and, regular vaccine matching to ensure vaccine effectiveness.
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.
Production and Characterization of Cellulolytic Enzymes by Chaetomium Globosum for Biomass Saccharification and Ethanol Production
(Discovery Journals, 2024) Munyasi, Kelvin Masinde; Omwenga, George Isanda; Mwamburi, Fredrick Mjomba
This study aimed to isolate, identify and characterize cellulase-producing fungi from a decaying tree trunk, and determine the effects of incubation time, moisture content and initial medium pH on cellulase production using untreated maize cobs and sugarcane bagasse under solid state fermentation after that, to saccharify for ethanol production. Samples were collected from Ngong Forest, Kenya, and screened for the isolation of cellulase producing fungi. The isolated fungi were grown to obtain pure cultures before DNA extraction, PCR amplification and sequencing. The fungus was cultured on substrates for cellulase production with enzymes obtained after fermentation subjected to cellulase assays; filter paper, exoglucanase and endoglucanase. Molecular data analysis was performed using the NCBI-BLAST algorithm and MEGA 11.0 software to identify the isolated fungus, while enzyme activity analysis was done using one-way ANOVA with R software at the P≤0.05 significance level, and the significant differences were determined via the Tukey post hoc test. The isolated fungus was identified as Chaetomium globosum. For the effect of incubation time on cellulase production, the fungus exhibited high enzyme production on different days within the incubation period, and the highest cellulase activity was recorded at a moisture content ratio of 1:2 and initial medium pH of 5. Saccharification optimization studies showed a 7% (v/v) enzyme concentration, 12% (v/w) substrate concentration and hydrolysis time of 72 hours were optimal for the maximum yield of reducing sugars. The total reducing sugar produced maximum bioethanol yield at 72 hours when Saccharomyces cerevisiae was used as a fermentation agent.
Anti-inflammatory Effects of Carissa spiranum Mediated via Attenuation of Leucocyte Migration
(The Journal of Phytopharmacology (TJP), 2024-05) Jeptoo, N Serem; Wambugu, Stanley N; Mwonjoria, John K.
Inflammation is a physiological process vital for pathogen elimination and tissue repair. However, left untreated, it can cause undesirable effects. There are several methods for management of the condition, including traditional remedies from plant sources that are thought to have few deleterious effects on the body, as is the case with steroids and NSAIDs. One of the plants widely used is Carissa spiranum, though little has been done to determine the effects of purified extracts on the condition and their mode of action. The present study investigated the effects of purified plant extract and its flavonoid-rich fraction on inflammation and leukocyte migration in mice. Formalin and carrageenan were used as the phlogistic substances in inflammation induction and leukocyte migration, respectively. While diclofenac sodium and dexamethasone were used as standard drugs. The diameter of the paw edema induced in the left hind paw of mice was measured and quantified as the edema developed in mice, while the number of leucocytes in peritoneal fluid lavage after pretreatment with carrageenan and determined with improved Neubauer chamber was used in the determination of the extent of leucocyte migration. The extracts exhibited a significant (p < 0.05) reduction in paw edema diameter and delayed leucocyte migration compared to the vehicle. These observations suggest that the plant extracts may contain compounds that exert their anti-inflammatory effects via attenuation of leucocyte migration.
Analysis of Antibiotics in Milk from Smallholder Farmers from Kenya Shows Traces Above the Recommended Maximum Residue Limits
(Science Publishing Group, 2024) Odeny, Bonnita Aluoch; Asudi, George Ochieng’; Omwenga, George; Oduor, Richard Okoth; Karau, Geoffrey Muriira
Antimicrobial resistance (AMR) is rising globally and is likely to cause more deaths because of antibiotic-resistant microbial infections and antibiotic residues in animal foods and products as a result of misuse of antibiotics in dairying. Thus, we determined the presence and quantities of sulfonamide, tetracycline, and beta-lactam drug residues in milk sampled in Nyandarua, Meru, and Kiambu counties in Kenya using the Charm TRIO® test kit and liquid chromatography (LC) coupled to the triple quadrupole mass spectroscopy (MS) (LC-MS/MS). The TRIO® test kit showed dicloxacillin as the most prevalent at 9.3%, followed by penicillin and cloxacillin at 3.7% each, and nafcillin at 0.9% among the beta-lactams. Among the tetracyclines, demeclocycline and tigecycline were the most prevalent at 10.3% each, followed by oxytetracycline at 9.3%, chlortetracycline at 7.5%, and doxycycline at 3.7%, while sulfaquinoxaline was the only sulfonamide drug detected at 4%. The LC-MS/MS detected the presence of all the tested β-lactam and tetracycline antimicrobial traces and all sulfonamide drugs except sulfamerazine in all three counties. All the tetracycline antibiotics recorded between 3 and 10.5% of antibiotic residues above the recommended Maximum Residue Levels (MRLs) in milk across all three counties, with beta-lactam antibiotics recording between 2 and 33.3%, indicating their misuse in the three counties. Sulfaquinoxaline was the only sulfonamide detected in milk samples above the recommended MRLs, indicating sulfonamides are less used in those counties. Therefore, it is important to enforce a regulatory framework to control antibiotic use in livestock to minimize potential health risks related to their traces in the foods.
Epidemiology of multi-drug resistant Tuberculosis in the western region of Kenya
(AIMS, 2024-04) Lugonzo, George O.; Njeru, Ezekiel M.; Songock, William; Okumu, Albert A.; Ndombi, Eric M.
Multidrug-resistant tuberculosis (TB) (MDR-TB), or TB that is simultaneously resistant to both isoniazid (INH) and rifampicin (RIF), is a barrier to successful TB control and treatment. Stratified data on MDR-TB, particularly in the high-burden western Kenya region, remain unknown. This data is important to monitor the efficacy of TB control and treatment efforts. Herein, we determined the molecular epidemiology of drug-resistant TB and associated risk factors in western Kenya. This was a non-experimental, population-based, cross-sectional study conducted between January and August 2018. Morning sputum samples of individuals suspected of pulmonary TB were collected, processed, and screened for Mycobacterium tuberculosis (Mtb) and drug resistance using line probe assay (LPA) and Mycobacterium growth indicator tubes (MGIT) culture. MGIT-positive samples were cultured on brain heart infusion (BHII) agar media, and the presence of Mtb was validated using Immunochromatographic assay (ICA). Drug sensitivity was performed on MGIT and ICA-positive but BHI-negative samples. Statistical significance was set at P < 0.05. Of the 622 Mtb isolates, 536 (86.2%) were susceptible to RIF and INH. The rest, 86 (13.83%), were resistant to either drugs or both. A two-sample proportional equality test revealed that the MDR-TB prevalence in western Kenya (5%) did not vary significantly from the global MDR-TB estimate (3.9%) (P = 0.196). Men comprised the majority of susceptible and resistant TB (75.9% and 77.4%%, respectively). Also, compared with healthy individuals, the prevalence of HIV was significantly higher in MDR-TB patients (35.9% vs 5.6%). Finally, TB prevalence was highest in individuals aged 25–44 years, who accounted for 58.4% of the total TB cases. Evidently, the prevalence of MDRTB in Western Kenya is high. Particular attention should be paid to men, young adults, and those with HIV, who bear the greatest burden of resistant TB. Overall, there is a need to refine TB control and treatment programs in the region to yield better outcomes.
Phytonutrient Screening and In vitro Antibacterial and Antifungal Properties of Polar and Nonpolar Extracts of Albizia gummifera, Prunus africana, and Combretum Molle from Mount Elgon Region, Kenya
(JAMB, 2024) Nguimbous, Simone Pierrette; Muthini, John Maingi; Wafula, Alphonse Wanyonyi; Mutuiri, Shem
Background: Globally, and particularly in less-developed countries, one of the principal factors associated with morbidity and mortality is infectious diseases. Over the years, the abuse and misuse of pharmaceutical products have caused an increase in resistant microbes, and consequently, today, the rate of infectious disease cases continues to increase to dangerously high levels as most medications have lost their efficacy. This indicates that there’s a need for new effective medications and calls for active research in drug discovery to curb this dangerous trend. Results: Obtained data demonstrated the presence of different bioactive compounds in the tested plant extracts such as glycosides, alkaloids, tannins, terpenoids, saponins, and phenols. Using the Kirby-Bauer disc diffusion method, P. africana methanol and ethyl acetate extracts showed significantly bigger inhibition zones compared to the rest against S. aureus (excluding controls). None of the tested extracts, however, were able to inhibit C. albicans and E. coli. The P. africana methanolic extract and the A. gummifera hexane, ethyl acetate, and methanolic extracts all inhibited the growth of S. aureus at the same minimum concentration of 31.25 mg/ml. The methanolic extract of C. molle exhibited the least activity against S. aureus, with an MIC of 250 mg/ml and mean zones of inhibition of 9.33±0.33 mm. Conclusions: This study revealed the presence of various phytoconstituents in crude extracts of the selected medicinal plants, but also highlighted the resistance of E. coli and C. albicans to these phytochemicals. The P. africana methanolic extract showed strongest inhibitory effect against S. aureus compared to the other plant extracts. The highest susceptibility was demonstrated by S. aureus, while E. coli and C. albicans were resistant to all the extracts. These findings support the usage of A. gummifera, P. africana, and C. molle in folk medicine against infections caused by S. aureus and highlight them as potential sources of phytonutrients for the development of new drugs.
Phenotypic and Genotypic Characterization of Extended Spectrum Beta-Lactamase-Producing Clinical Isolates of Escherichia coli and Klebsiella Pneumonia in Two Kenyan Facilities: A National Referral and a Level Five Hospital
(Hindawi, 2024-02) Maveke, Sylvia M.; Aboge, Gabriel O.; Kanja, Laetitia W.; Mainga, Alfred O.; Gachau, Naftaly; Muchira, Beatrice W.; Moriasi, Gervason A.
Prospects of classical biological control of papaya mealybug in Kenya: Performance of its exotic parasitoid, Acerophagus papayae, under laboratory and field conditions
(Elsevier Ltd, 2023) Opisa, Selpha; Makale, Fernadis; Nyasani, Johnson O.; Muvea, Alexander; Kabole, Mellon; Chacha, Duncan; Agboyi, Lakpo Koku; Asudi, George O.; Rehman, Abdul; Luke, Belinda; Rwomushana, Ivan
Papaya mealybug (PMB), Paracoccus marginatus, native to Mexico and Central America, invaded Kenya in 2016 causing severe yield losses of between 57% and 91% and £2224/ha household economic losses annually. A classical biological program for PMB involved the importation of Acerophagus papayae, a koinobiont endoparasitoid, from Ghana into the quarantine facility at Kenya Agricultural and Livestock Research Organization, Muguga. Laboratory bioassays were conducted to evaluate the suitability of A. papayae to parasitize PMB. Parasitism rates, sex ratio and development time of the parasitoid were evaluated under choice and no-choice experimental conditions. High parasitism rates of 72.5 ± 5.9 and 75.0 ± 3.8% were recorded in third instar and adult female PMB, respectively, and lower parasitism rates of 43.8 ± 4.6 % were recorded in second instars, under no-choice test conditions. Significant differences in host choice were noted when A. papayae was offered several host stages, with third instars being preferred over second instars. Adult females were preferred over third instars. Adult parasitoids were released and monitored for their establishment at six papaya farms in the Coastal region of Kenya from December 2021 to November 2022. Parasitoid establishment was recovered within the first month of release. Parasitism levels varied across the sites with the highest parasitism of 72.89 % recorded in Kwale. Findings from this study highlight the potential of A. papayae as a good candidate for biological control of PMB in Kenya and Africa beyond.
Molecular Characterization of Indigenous Rhizobia from Kenyan Soils Nodulating with Common Beans
(mdip, 2023-05) Wekesa, Clabe; Kiprotich, Kelvin; Okoth, Patrick; Asudi, George O.; Muoma, John O.; Furch, Alexandra C. U.; Oelmüller, Ralf
Kenya is the seventh most prominent producer of common beans globally and the second leading producer in East Africa. However, the annual national productivity is low due to insufficient quantities of vital nutrients and nitrogen in the soils. Rhizobia are symbiotic bacteria that fix nitrogen through their interaction with leguminous plants. Nevertheless, inoculating beans with commercial rhizobia inoculants results in sparse nodulation and low nitrogen supply to the host plants because these strains are poorly adapted to the local soils. Several studies describe native rhizobia with much better symbiotic capabilities than commercial strains, but only a few have conducted field studies. This study aimed to test the competence of new rhizobia strains that we isolated from Western Kenya soils and for which the symbiotic efficiency was successfully determined in greenhouse experiments. Furthermore, we present and analyze the whole-genome sequence for a promising candidate for agricultural application, which has high nitrogen fixation features and promotes common bean yields in field studies. Plants inoculated with the rhizobial isolate S3 or with a consortium of local isolates (COMB), including S3, produced a significantly higher number of seeds and seed dry weight when compared to uninoculated control plants at two study sites. The performance of plants inoculated with commercial isolate CIAT899 was not significantly different from uninoculated plants (p > 0.05), indicating tight competition from native rhizobia for nodule occupancy. Pangenome analysis and the overall genome-related indices showed that S3 is a member of R. phaseoli. However, synteny analysis revealed significant differences in the gene order, orientation, and copy numbers between S3 and the reference R. phaseoli. Isolate S3 is phylogenomically similar to R. phaseoli. However, it has undergone significant genome rearrangements (global mutagenesis) to adapt to harsh conditions in Kenyan soils. Its high nitrogen fixation ability shows optimal adaptation to Kenyan soils, and the strain can potentially replace nitrogenous fertilizer application. We recommend that extensive fieldwork in other parts of the country over a period of five years be performed on S3 to check on how the yield changes with varying whether conditions.
Old and New Association of Cotesia icipe (Hymenoptera: Braconidae) with Alien Invasive and Native Spodoptera Species and Key Stemborer Species: Implication for their Management
(John Wiley & Sons Ltd, 2023-08) Obala, Francis; Mohamed, Samira A; Magomere, titus Obidi; Subramanian, Sevgan
BACKGROUND: Maize production in Africa is hindered by a myriad of biotic challenges, key among them being invasive and native lepidopteran stemborers. Recent invasion of the continent by fall armyworm, Spodoptera frugiperda, has further exacerbated the situation. Fortunately, Cotesia icipe was found to be very promising against S. frugiperda. However, the co-occurrence and interaction between S. frugiperda and the stemborers (Busseola fusca, Sesamia calamistis, and Chilo partellus) in maize agroecosystem may jeopardize the efficiency of C. icipe as a biocontrol agent of S. frugiperda. This study investigated the performance of C. icipe on S. frugiperda, Spodoptera littoralis and the stemborers. Specifically, the preference and acceptability of C. icipe to the host insects, the physiological suitability of the hosts for its development, and the effect of these hosts on the fitness parameters of the offspring were assessed. RESULTS: Cotesia icipe accepted all the tested hosts, albeit with higher preference for Spodoptera species than for stemborers under multiple-choice tests. Also, the highest parasitism of up to 97% was recorded on S. frugiperda compared with parasitism on the stemborers of 43% in B. fusca. Moreover, physiological suitability and fitness traits (except for per cent female offspring) varied with host species, again being optimal on Spodoptera species. CONCLUSION: Cotesia icipe demonstrated strong potential to control S. frugiperda in maize due to its high affinity for parasitization and developmental success in this host; and despite its non-specific parasitization, the presence of other hosts may not prevent its maximum control of S. frugiperda
In Vivo Ameliorative Effects of Vitamin E against Hydralazine-Induced Lupus
(BMJ, 2023) Githaiga, Fiona Muthoni; Omwenga, George Isanda; Ngugi, Mathew Piero
ABSTRACT Objective In this study, we investigated the in vivo ameliorative effects of vitamin E in a hydralazine-induced lupus model, which closely resembles SLE in humans. We aim to shed light on its potential as a therapeutic agent for managing SLE. Methods Forty BALB/c mice were used in this study. Hydralazine hydrochloride was orally administered in a concentration of 25mg/kg to the five mice groups once weekly for a period of 5weeks to induce a lupus-like condition. The untreated group was the normal control group. To confirm the development of lupus, an ANA test was conducted. After the mice tested positive for ANA, drug treatments commenced. The negative control group did not receive any drug treatment. The treatments included prednisolone, methotrexate and vitamin E, all administered at a concentration of 25mg/kg, with a higher dose of vitamin E (50mg/kg) also administered. Results Notably, on day 35, after drug treatment, we observed that mice that received vitamin E at a dosage of 50mg/kg (3.01±0.100) had a slight decrease in lymphocyte hydrogen peroxide radicals when compared with the group receiving 25mg/kg of vitamin E (3.30±0.100) (p<0.05). This finding suggests that the scavenging potential of vitamin E is dose dependent. Conclusion This study suggests that vitamin E supplementation, especially at a higher dose (50mg/ kg), holds promise in ameliorating lupus-like conditions. These findings warrant further exploration and may offer a potential avenue for improving the disease status of patients experiencing SLE.
Occurrence of Passion Fruit Woodiness Disease in the Coastal Lowlands of Kenya and Screening of Passion Fruit Genotypes for Resistance to Passion Fruit Woodiness Diseas
(Springer Nature, 2023) Asande, Lydia K.; Ombori, Omwoyo; Oduo, Richard O.; Nchore, Shem B.; Nyaboga, Evans N.
Background Passion fruit (Passifora edulis [Sims]) is an important economic fruit crop in Kenya, grown for domestic, regional and international markets. However, passion fruit production is constrained by both biotic and abiotic stresses. Passion fruit woodiness disease (PWD) complex is the most injurious viral disease responsible for yield losses of up to 100%. In East Africa, it is caused by potyviruses. The most efective way to manage PWD is by using resistant cultivars. The objectives of this study were to determine the occurrence of passion fruit woodiness disease in selected counties at the Coastal lowlands of Kenya and screen farmer preferred passion fruit genotypes for resistance to PWD. Results In the present study, it was established that all surveyed farms in Kwale and Kilif counties displayed passion fruit woodiness virus disease symptoms. The highest disease incidence of 59.16% and 51.43% was observed at Kilif and Kwale counties, respectively. A signifcant diference (p<0.05) in symptom severity was observed within the tested genotypes with purple and banana passion fruits having the highest and lowest AUDPC values, respectively, both under greenhouse and feld conditions. ACP ELISA assays using universal potyvirus antiserum (Agdia Inc., Elkhat, IN) confrmed that the observed characteristic symptoms of woodiness disease were as a result of potyvirus infection. Conclusions The fndings herein indicate that PWD is widespread in both Kilif and Kwale counties with low to moderate disease incidence and severity. The observed prevalence, incidence and severity levels of PWD in Kwale and Kilif counties could be aggravated by poor management practices such as non-sterilization of pruning tools, intercropping with target crops and crop rotation with the same target crops. Response of passion fruit genotypes to woodiness viruses was genotype dependent. There is need to sensitize farmers on the cause and spread of PWD and management strategies in order to increase production and enhance the quality of fruits.
A simple and fast Agrobacterium-mediated transformation system for passion fruit KPF4 (Passifora edulis f. edulis×Passifora edulis f. favicarpa)
(Springer Nature, 2020) Asande, Lydia K.; Omwoyo, Richard O.; Oduor, Richard O.; Nyaboga, Evans N.
Abstract Background: Passion fruit (Passifora edulis Sims) is an important horticultural crop in the tropics and subtropics, where it has great commercial potential due to high demand for fresh edible fruits and processed juice as well as source of raw materials in cosmetic industries. Genetic engineering shows great potential in passion fruit improvement and can compensate for the limitations of conventional breeding. Despite the success achieved in genetic modifcation of few passion fruit varieties, transgenic passion fruit production is still difcult for farmer-preferred cultivars. Therefore, it is important to establish a simple and fast Agrobacterium-mediated cell transformation of commercial hybrid passion fruit KPF4 (Passifora edulis f. edulis×Passifora edulis f. favicarpa). Results: In the present study, we have developed a simple and fast Agrobacterium-mediated transformation system for hybrid passion fruit KPF4 using leaf disc explants. Factors afecting the rate of transient beta (β)-glucuronidase (gusA) expression and consequently transformation efciency were optimized as follows: Agrobacterium cell density with an OD600 of 0.5, 30 min infection time, 3 days of co-cultivation duration and the incorporation of 200 µM acetosyringone into Agrobacterium infection suspension medium. Using the optimized conditions, transgenic plants of KPF4 were produced within 2 months with an average transformation efciency of 0.67%. The β-glucuronidase (GUS) histochemical staining confrmed the expression and integration of an intron-containing gusA gene into transformed leaf discs and transgenic plant lines of KPF4. The presence of gusA gene in the transgenic plants was confrmed by polymerase chain reaction (PCR). The results confrmed that the gusA gene was efciently integrated into the passion fruit genome. Conclusions: The developed transformation protocol is simple and rapid and could be useful for functional genomic studies and transferring agronomically important traits into passion fruit hybrid KPF4. This study developed a method that can be used to transfer traits such as resistance to viral diseases, low fruit quality and short storage life. To the best of our knowledge, this is the frst report on genetic transformation system for commercial passion fruit hybrid KPF4.
Optimization of Growth Conditions for Chlorpyrifos-Degrading Bacteria in Farm Soils in Nakuru County, Kenya
(Hindawi, 2024-01) Wachira, Peter; Huria, Nderitu; Sifuna, Paul; Essuman, Suliman; Asamba, Micah
Chlorpyrifos (CP) is a chlorinated organophosphate pesticide. In Kenya, it is commonly used as an acaricide, particularly in dairy farming, leading to soil and water contamination. The study is aimed at isolating bacteria with CP-degrading potential and optimizing their growth conditions, including temperature, pH, and CP concentration. The enrichment culture technique was used, with minimal salt medium (MSM) supplemented with commercial grade CP. A multilevel factorial design was used to investigate the interactions of temperature, pH, and CP concentration. According to the findings, seven bacterial strains with potential to degrade CP were characterized and identified as Alcaligenes faecalis, Bacillus weihenstephanensis, Bacillus toyonensis, Alcaligenes sp. strain SCAU23, Pseudomonas sp. strain PB845W, Brevundimonas diminuta, and uncultured bacterium clone 99. Growth and biodegradation of bacteria differed significantly among the isolates across pH value, temperature, and concentrations (P ≤ 0 05). The optimum conditions for growth were pH 7, temperature of 25° C, and 25mg/l chlorpyrifos concentration, while optimum degradation conditions were pH 5, temp 25° C, and CP conc. 25mg/l. The Pearson correlation between optimum growth and degradation showed a weak positive relationship (R = 0 1144) for pH and strong positive relationship for temperature and concentration of chlorpyrifos. Other than pH, the study shows that there could be other cofactors facilitating the chlorpyrifos degradation process. The findings show that an efficient consortium, at 25° C and pH 5, can include Bacillus toyonensis 20SBZ2B and Alcaligenes sp. SCAU23 as they showed high optical density (OD) values under these conditions. These results indicate the potential for these bacteria to be employed in chlorpyrifos-contaminated ecosystem detoxification efforts upon manipulation of natural growth conditions. The findings of this study offer a potential foundation for future research into the reconstitution of a consortium. Based on the optimum conditions identified, the isolated bacterial strains could be further developed into a consortium to effectively degrade CP in both laboratory and field conditions. Dairy farmers can utilize the isolated strains and the consortia to decontaminate farm soils
Nanoparticle Treatments Based on Zinc Oxide and Moringa oleifera Leaf Extracts Alleviate Salinity Stress in Faba Bean (Vicia faba L.)
(Scientific Research Publishing, 2022) Ragab, Sherif M.; Turoop, Losenge; Runo, Steven; Nyanjom, Steven
Salinity stress limits crop growth and productivity, including legumes in various regions worldwide. The impact of foliar-applied zinc nanoparticles (ZnNPs) and combined zinc nano-loaded with moringa extracts (ZnONPs) on salt tolerance in faba beans (cultivar, Giza-716) grown under saline soil (50 and 100 mM NaCl) was investigated. Moringa oleifera extract has been used as a chelating agent to synthesize zinc oxide nanoparticles. The crystalline structure, morphology, and chemical composition of ZnO nanoparticles were studied using various characterization techniques, including UV-visible spectroscopy (UV), Fourier Transform Infrared Analysis (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Morphological, chemical, and biochemical parameters of plants at 60 and 90 days after sowing were assessed. Salinity stress caused a remarkable reduction in growth traits, photosynthetic pigments and proline levels of the faba bean. Foliar spray with ZnNPs and ZnONPs on faba bean grown under saline soils promoted plant growth parameters (i.e., shoot length, numbers of leaves, relative water content, shoot and roots fresh and dry weights), photosynthetic pigments (Chl a, b, total chlorophyll, and carotenoids), proline and mineral elements (Na+, K+, Ca2+, and Zn2+) compared to control. However, at 100 mM NaCl, there were no significant variations in the mentioned parameters. This study suggested that there is potential for foliar spraying with ZnNPs and ZnONPs in improving growth parameters, photosynthesis efficiency and biochemical aspects of faba bean plants under saline conditions.

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