Department of Biological Sciences

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Start date: 2025

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    ASSESSMENT OF THE BACTERIAL PROFILE OF LARVAL AND ADULT ANOPHELINES IN SOUTH-WEST NIGERIA AND IMPLICATIONS FOR PERMETHRIN RESISTANCE
    (Covenant University, Ota, 2026-09) Oluwaseyi, Temitope Ayinde; Covenant University, Thesis
    Malaria remains one of the major scourges and a contributor to morbidity and mortality in Nigeria. Despite efforts made by the National Malaria Elimination Program and its partners to control malaria, malaria still remains a major public health issue in Nigeria. Data from sentinel sites indicate that mosquitoes are now resistant to major classes of insecticides, necessitating a deeper understanding of vector dynamics. This study investigated the physicochemical parameters, heavy metal concentrations, algal toxin composition, and characterised the bacterial communities associated with mosquito larvae and permethrin-resistant and susceptible adult Anopheles mosquitoes collected from urban and rural communities in Ogun and Oyo States, Nigeria, between July and December 2024. The spatial distribution of the breeding sites was georeferenced, and the physicochemical parameters were measured in accordance with the American Public Health Association (APHA) standard protocols. The bacterial communities in the water samples, larvae, resistant, and susceptible adult mosquitoes were profiled using 16S rRNA PacBio sequencing, and functional metagenomics was performed with PICRUST2. Anopheles mosquitoes were identified using morphological keys and molecular characterisation by PCR techniques, and permethrin susceptibility was carried out following the WHO standard procedures. One hundred and twenty breeding sites were sampled, and six types of breeding sites were identified. Across the breeding sites, puddles had the highest occurrence of mosquito larvae habitats (56.7%), construction sites containers (15.8%), Tyres (13.3%), Drains (6.7%), Bowls (5.8%), and Wells (1.7%). Physicochemical parameters, such as Chemical Oxygen Demand, Temperature, and pH, were high at breeding sites with no larvae presence in urban and rural areas across Oyo and Ogun states. Larvae presence was identified in breeding sites with algal toxins, and the presence of saxitoxins influenced the presence of larvae. The bacterial composition of the water samples was 80% Gramnegative and 20% Gram-positive with four most abundant taxa which include the Pseudomonas 22%, Aeromonas (15%), Serratia (10%), and Enterobacter (7%). Comparing the microbial communities in urban and rural sites revealed no substantial variation in their composition across the breeding sites; however, across the developmental stages, the bacterial communities of mosquitoes varied greatly. Among the mosquito larvae, Anophelines larvae were present in 62.4% of the habitats, Culicine larvae in 8%, Aedes larvae in 25.8% while there was a co-occurrence of Culicine and Aedes larvae in 3.2% of the habitats. Two members of the Anopheles gambiae (Anopheles arabiensis and Anopheles colluzzii) family were identified as malaria vectors using polymerase chain reaction. High knockdown rates and resistance were observed in rural and urban Local Government Areas (LGAs) in Ogun state.
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    EVALUATION OF LYTIC BACTERIOPHAGES FOR MULTI-DRUG RESISTANT Pseudomonas aeruginosa ISOLATED FROM SELECTED CLINICAL SAMPLES
    (Covenant University, Ota, 2026-08) ADELEYE, Olufunmilayo Damilola; Covenant University, Dissertation
    Pseudomonas aeruginosa is one of the Gram-negative pathogens most difficult to isolate clinically because of its propensity to acquire resistance determinants against almost all antibiotics currently in use. The goal of this study was to define the spectrum of resistance in clinical isolates from a local region and to examine the hypothesis that indigenous phages obtained from the environment might serve as a biological control for these isolates. Specimens (wound, urine, high vaginal, urethral, anus and ear swabs) were plated onto selective and general growth media and the isolates presumptive to be Pseudomonas were confirmed by microscopical and biochemical tests (gram stain, oxidase, catalase, TSI). The confirmed isolates were tested for sensitivity to twelve antibiotic agents by the Kirby-Bauer disc diffusion method, and in some cases further confirmed using 16S rRNA gene sequencing. Raw sewage was screened as a potential phage source by enrichment using a clinical strain, filtration, double-layer agar plating, and Transmission electron microscopy to visualise the phages present in the environment. We collected 12 Pseudomonas strains from 36 clinical samples; it was evident that all the isolates were multi-resistant to almost every tested β-lactam, fluoroquinolone, macrolide and aminoglycoside drugs; isolates are sensitive to levofloxacin and gentamicin, respectively. The 16S rRNA sequences showed not only Pseudomonas aeruginosa but also three related species: Pseudomonas putida, Pseudomonas mendocina, Pseudomonas stutzeri. The later information suggests that after culturing and biochemical testing a wider range of species can be identified from a bacterial population. The enrichment allowed us to obtain lytic phages able to lyse all of the multi-resistant Pseudomonas strains: the zones of lysis were round, distinct and 1-3 mm in diameter; the particles identified via electron microscopy were tailed icosahedral phages of approx. 20 nm and with short, non-contractile tails. In conclusion, multi-resistant Pseudomonas isolates do remain present in the investigated population of Nigeria, and the sewage is an easily and accessible natural source of Pseudomonas-active lytic phages. This study gives useful data specific for Nigeria to be further investigated on the lytic activity of phages against Pseudomonas aeruginosa.
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    IN VIVO IN VITRO ANTI-PLASMODIAL ACTIVITY OF CHEMICALLY SYNTHESISED IMIDAZOLE COMPOUNDS
    (Covenant University, Ota, 2026-09) OJO, Oluwaferanmi Esther; Covenant University, Dissertation
    Malaria remains a leading cause of morbidity and mortality globally, with the continued emergence of Plasmodium falciparum resistance to artemisinin-based therapies rendering the identification of novel chemotherapeutic scaffolds an urgent priority. The imidazole family of compounds, with their adaptable framework and ability to engage parasite-specific targets such as falcipain-2 and hemozoin biosynthesis machinery, represent compelling synthetic leads. This study evaluates the in vitro anti-plasmodial activity and in vivo efficacy and safety profiles of two newly synthesised compounds: 4,5-diphenyl-2-(m-tolyl)-1H-imidazole (IM1) and 4,5-diphenyl-2- (m-tolyl)-1-tosyl-1H-imidazole (IM2). In vitro susceptibility was assessed using a schizont maturation inhibition assay against the chloroquine-sensitive P. falciparum 3D7 strain. In vivo evaluation employed Peter's 4-d suppressive test in P. berghei ANKA-infected Swiss albino mice administered oral doses of 20–400 mg/kg. Acute toxicity was assessed according to the OECD 423 guidelines through haematological, biochemical, oxidative stress, and histopathological analyses. In vitro, IM1 demonstrated higher intrinsic potency, exhibiting a half-maximal inhibitory concentration (IC50) of 3.6 ± 0.2 μg/mL compared to 7.8 ± 0.5 μg/mL for IM2. However, in vivo evaluation revealed a distinct efficacy paradox: IM2 demonstrated superior systemic efficacy, achieving up to 68% parasitaemia suppression at 400 mg/kg, surpassing the 52% suppression observed with IM1. IM2 also significantly extended the mean survival time of infected mice to 12.3 d, compared with 8.1 d for untreated controls. Systemically, IM2 maintained physiological homeostasis, preserved hepatic and renal architecture, and induced significant modulation and stabilization of circulating lymphocytes (p=0.049), compared with the abnormal increase observed in untreated infections. A strong positive correlation between malondialdehyde and glutathione (r=0.839, p=0.005) indicated a well-tolerated, reactive oxygen species-mediated parasiticidal mechanism for IM2. On the other hand, high-dose IM1 (400 mg/kg) induced dose-dependent hepatotoxicity, as evidenced by elevated alanine aminotransferase (44.47 U/L) and histopathological evidence of hepatocyte vacuolation. Ultimately, whilst IM1's highly lipophilic core necessitates structural optimization to mitigate hepatic stress, IM2 represents a promising lead compound that requires further pre-clinical investigations.
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    The Impact of Plasmodium falciparum Adenosine Triphosphatase-6 Gene (PfATPase6) Mutations in Artemisinin Resistance
    (Journal of Pure and Applied Microbiology, 2025) Obafemi, Dorcas Yemisi; Atokolo, Austine
    The World Health Organization (WHO) recorded an estimated 263 million malaria cases globally in 2023, leading to about 597,000 mortalities. Most of this burden occurred in the WHO African Region, which accounted for approximately 94% of cases and 95% of malaria-related deaths. Artemisininbased combination therapies (ACTs) remain the mainstay of malaria treatment globally; however, the emergence of Plasmodium falciparum resistance compromises their sustained efficacy. Although mutations in the Plasmodium falciparum Kelch 13 (Pfk13) propeller domain are largely proven to be markers of partial artemisinin resistance, greater focus has turned to Plasmodium falciparum Adenosine Triphosphatase 6 (PfATPase6) as a potential supplementary determinant. This review compiled evidence from published articles between 2015 and 2025, sourced from Google Scholar, PubMed, ProQuest, and ScienceDirect, with a focus on PfATPase6 polymorphisms, their distribution, functional role, detection techniques, and implications for malaria prevention. Notable nonsynonymous single-nucleotide polymorphisms (SNPs) such as E431K, S769N, A623E, S769M, and M699V have been reported spanning Asia, the Americas, and Africa. Several studies reveal a correlation with decreased in vitro susceptibility or enhanced artemether Half Maximal Inhibitory Concentration (IC50), although findings are inconsistent due to interrelated resistance markers, environmental differences, and deviations in methodology. Recent improvements in molecular monitoring techniques, like nextgeneration sequencing, high-resolution melting analysis, and advanced real-time polymerase chain reaction (PCR) techniques, have broadened the ability to detect uncommon variants and have reinforced surveillance systems. Despite inconsistency in findings, there is evidence that PfATPase6 reduces sensitivity to artemisinin; therefore, it should be taken into consideration in resistance surveillance schemes. It is recommended to incorporate PfATPase6 genotyping alongside Pfk13 surveillance and treatment efficacy studies to offer more insights into the emergence of resistance. These approaches are vital to expound the underexplored role of the PfATPase6 in resistance patterns and encourage the sustainability of antimalarial drugs.
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    Co-expression of Pfcrt and pfmdrl Genes in Malaria Patients: Novel Treatment Techniques
    (Springer Nature Switzerland, 2025) Obafemi, Dorcas Yemisi; Atokolo, Austine; Akinduti, Paul Akinniyi
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    Performance assessment of Bayesian meta-analytic predictive model on kdr mutation in insecticide-resistant malarial vectors in sub-Saharan Africa.
    (Malaria Journal, 24(1),, 2025) Ahuekwe, E. F.; Taiwo, D. I.
    Mosquito populations’ selective pressure arising from the widespread and prolonged use of insecticides, especially pyrethroids, for both agricultural usages and public health outcomes, has immensely contributed to the emergence and heavily spread of insecticide resistance. In this study, a systematic review identified eight eligible case–control or cohort studies published between 2015 and 2025 across sub-Saharan Africa that reported both allele and/or genotype frequencies of L1014F and L1014S. The predictive performance and inferential robustness of a Bayesianw meta-analytic model were applied and evaluated on two knockdown resistance (kdr) mutations, L1014F and L1014S, in the Anopheles mosquito populations. Using the Markov Chain Monte Carlo (MCMC) sampling to compute pooled concordance statistics, odds ratios, and perform funnel plot asymmetry tests (Egger, Macaskill, Debray). The results revealed that L1014F showed a stronger and more consistent association with phenotypic resistance compared to L1014S, with odds ratios (OR) as high as 4.44 (95% CI 3.40–5.80). However, concordance statistics for both mutations demonstrated wide confidence intervals (L1014F: 0.141; CI − 0.095 to 0.459; L1014S: 0.169; CI − 0.399 to 0.688), indicating moderate predictive reliability. The Bayesian framework effectively synthesized complex and heterogeneous resistance data, confirming the operational relevance of KDR mutations in resistance surveillance. The global significance of these results enhances the predictive analytics in resistance management, such that resistance evolution is temporally and spatially dynamic. The integration of Bayesian modelling into existing entomological surveillance systems shifts the paradigm towards more adaptive and anticipatory management. Although data sparsity and regional heterogeneity warrant cautious interpretation, integrating ecological and thermodynamic variables into predictive models is essential for enhancing future resistance forecasting.
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    Impact of multi-active ingredient long-lasting insecticidal nets for malaria vector control in sub-Saharan Africa: a systematic review and meta-analysis
    (Discover Public Health 23(1), 2026) Ahuekwe, E. F.; Taiwo, D. I.
    Strong selective pressures on mosquitoes arise from an over-reliance on a narrow range of insecticides and the continuous increase in insecticide resistance. This increased resistance weakens the effectiveness of conventional single-ingredient vector control interventions, thus undermining the efforts to reduce malaria transmission. This study aimed to assess the comparative efficacy of multi-active ingredients interventions, which include pyrethroid combinations with pyriproxyfen, chlorfenapyr, and piperonyl butoxide (PBO), versus single-active ingredients approaches in reducing malaria prevalence and key entomological outcomes in malaria-endemic regions. A systematic review and meta-analysis were conducted in accordance with the PRISMA guidelines. Studies were selected based on specific inclusion criteria, including randomised controlled trials conducted in sub-Saharan Africa and interventions focused on multi-active ingredient (MAI) approaches. Data on malaria prevalence, vector density, sporozoite rate, and entomological inoculation rate (EIR) were extracted. Random- and fixed-effects models were applied to evaluate the pooled effects, and heterogeneity was assessed using a diagnostic plot. Publication bias was examined using funnel and forest plots. Four studies met the inclusion criteria, which comprise a total of 135,706 households for pyrethroid-only ITNs, 117,652 for pyrethroid-pyriproxyfen, 118,518 for pyrethroid-chlorfenapyr, and 63,331 for pyrethroid-PBO interventions. Chlorfenapyr-pyrethroid combinations showed the most substantial reduction in malaria prevalence (adjusted odds ratio (aOR) 0.53; 95% CI: 0.30–0.67) and entomological inoculation rate (aOR 0.13; 95% CI: 0.07–0.31). Although pyriproxyfen and PBO combinations also reduced vector density and sporozoite rates, chlorfenapyr exhibited the highest efficacy, especially in regions with established pyrethroid resistance. Publication bias was observed, resulting in a slight overestimation of the effectiveness of MAI-LLINs interventions. MAI-LLINs approaches, particularly chlorfenapyr-pyrethroid interventions, have demonstrated superior effectiveness compared to single-active-ingredient (SAI) LLIN interventions in reducing malaria transmission metrics in sub-Saharan Africa. While the results underline the potential of MAI-LLINs strategies, further research and collaborative studies are needed to optimise MAI-LLINs deployment, assess long-term impacts on resistance, and ensure cost-effectiveness in resource-limited settings.
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    Post-germination Application of Trichoderma asperellum for the Biocontrol of Macrophomina phaseolina in Cowpea
    (Tropical Journal of Natural Product Research Vol 9, Issue 12,, 2025) Oyesola, Olusola L.; Kinge, Tonjock R.; Kolade, Olufisayo A.; Obembe, Olawole O.
    Cowpea (Vigna unguiculata (L.) Walp.) serves as a food source for humans and forage for animals. However, its production is affected by disease-causing fungi, of which Macrophomina phaseolina is a significant pathogen. Trichoderma was employed as a biofungicide to manage the disease in the screenhouse. Three strains of Trichoderma asperellum were isolated from the soil. The fungal spore suspensions of the Trichoderma strains were prepared, formulated into seven different treatment combinations, and applied to the cowpea potted soil five days after the germination of the cowpea to investigate their biocontrol ability on M. phaseolina and assess their effects on cowpea growth. The experiment's results showed that cowpea plants treated with T. asperellum differed significantly in plant height, stem girth, and leaf number compared to those treated with M. phaseolina alone (p < 0.05). Trt3 (54.6815 cm), Trt1 (54.0125 cm), and Trt5 (52.9375 cm) gave a higher plant height than in control 1 (M. phaseolina-treated cowpea - 44.9667 cm). Also, Trt7 (0.5413) and Trt3 (0.5258) gave a higher stem girth than in control 1 (M. phaseolina-treated cowpea - 0.3333 cm), while Trt6 (20.292) gave a higher leaf number than in control 1 (M. phaseolina-treated cowpea - 8.833). Additionally, Trt3 and Trt7 exhibited disease incidences of 22% and 67%, respectively, compared to control 1, which had a 100% incidence. Meanwhile, Trt7 showed 8% disease severity, compared to control 1, which had 100%. Therefore, post-germination Trichoderma application proved to be an effective strategy for controlling M. phaseolina, and it also has the potential to enhance cowpea biomass for sustainable food security
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    Post-germination Application of Trichoderma asperellum for the Biocontrol of Macrophomina phaseolina in Cowpea
    (Tropical Journal of Natural Product Research, 2025) Oyesola, Olusola L.; Kinge, Tonjock R.; Kolade, Olufisayo A; Obembe, Olawole O
    Cowpea (Vigna unguiculata (L.) Walp.) serves as a food source for humans and forage for animals. However, its production is affected by disease-causing fungi, of which Macrophomina phaseolina is a significant pathogen. Trichoderma was employed as a biofungicide to manage the disease in the screenhouse. Three strains of Trichoderma asperellum were isolated from the soil. The fungal spore suspensions of the Trichoderma strains were prepared, formulated into seven different treatment combinations, and applied to the cowpea potted soil five days after the germination of the cowpea to investigate their biocontrol ability on M. phaseolina and assess their effects on cowpea growth. The experiment's results showed that cowpea plants treated with T. asperellum differed significantly in plant height, stem girth, and leaf number compared to those treated with M. phaseolina alone (p < 0.05). Trt3 (54.6815 cm), Trt1 (54.0125 cm), and Trt5 (52.9375 cm) gave a higher plant height than in control 1 (M. phaseolina-treated cowpea - 44.9667 cm). Also, Trt7 (0.5413) and Trt3 (0.5258) gave a higher stem girth than in control 1 (M. phaseolina-treated cowpea - 0.3333 cm), while Trt6 (20.292) gave a higher leaf number than in control 1 (M. phaseolina-treated cowpea - 8.833). Additionally, Trt3 and Trt7 exhibited disease incidences of 22% and 67%, respectively, compared to control 1, which had a 100% incidence. Meanwhile, Trt7 showed 8% disease severity, compared to control 1, which had 100%. Therefore, post-germination Trichoderma application proved to be an effective strategy for controlling M. phaseolina, and it also has the potential to enhance cowpea biomass for sustainable food security.
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    Stabilization and Environmental Sustainability of Swelling Clays Soils: A Review
    (COVENANT JOURNAL OF PHYSICAL AND LIFE SCIENCES, VOL. 13, NO. 2, 2025) Oziegbe, Ehitua J.; Oziegbe, Olubukola
    Water movement in swelling soils conforms with material continuity. This invariably justifies the differences in the gravitational potential energy during expansion and the anisotropic stresses that press the soil but allow for vertical movement. Under fluid conditions, vane efficiency exhibited by macropores is lowered by swelling of the clay, and a poorly drained soil results in surface saturation. The type of water applied to soil material tends to have an impact on the positioning of cracks in swelling clays, and thus, cracks can remain pathways for preferential flow much after they are covered at the soil surface. Over time, chemicals and chemical compounds have been utilized to further enhance the engineering properties of such soils. However, environmentally friendly biodegradable biological stabilizers are taking the place of conventional stabilizers, most especially lime and cement. Additionally, biochar amendment, which is ecofriendly, has also been found to lower the swelling index capability of expansive clay soil. Despite the dangers associated with swelling clay, it has found extensive use as adsorbents, carriers in drug delivery systems, and the building of a storage tank for the disposal of radioactive materials. In addition, swelling clays have found significant usage in the production of controlled-release fertilizers (CRFs) formulations. Hence this paper emphasizes the environmental impact of building large structures and road construction on swelling clay soils, highlights recent progress in the inhibition and stabilization of swelling soils to sustain the environment, and enumerates the economic importance associated with swelling clay soils.