Research Articles (Biotechnology)

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Browsing by Author "Daniel, Augustine Innalegwu"

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    Effects of ZnO nanoparticles concentration on the morphology and textural properties of ZnO/NiFe2O4 nanocomposite
    (Elsevier B.V., 2025) Daniel, Augustine Innalegwu; Keyster, Marshall; Tijani, Jimoh Oladejo
    The aim of this study is to synthesize and characterize ZnO and NiFe2O4 nanoparticles via green route and co-precipitation of ZnO/NiFe2O4. X-ray diffraction (XRD) data show no extra diffraction peaks belonging to other phases except wurtzite. High resolution transmission electron microscopy (HRTEM) images showed that the average interplanar distance of wurtzite phase at 3, 5, and 7 % dopant concentration were about 0.28, 0.44 and 0.33 nm respectively. X-ray photoelectron spectroscopy (XPS) results show difference in binding energies of the elements present in different concentration of the dopants. Electron Energy Loss Spectroscopy (EELS) spectra show similarities in the shape of Zn, Fe and Ni from zero loss, low loss and core loss region with a little shift in energy. All the elements exhibit multiple oxidation state; +2 and +3 for Fe and +1 and +2 for Zn and Ni. Brunauer-Emmett-Teller (BET) plot shows that ZnO belongs to the type II isotherm curve while NiFe2O4 and 3, 5 and 7 % ZnO/NiFe2O4 all belong to type IV isotherm curve indicating ZnO as macroporous while NiFe2O4 and different dopant concentration of ZnO/NiFe2O4 are mesoporous. The study shows the complete synthesis of ternary ZnO/NiFe2O4 nanocomposites using green synthesis and sol-gel approach. • Green synthesis of ZnO and NiFe2O4 using leaf extract of Anacardium occidentale • Co-precipitation method at different concentration of ZnO and NiFe2O4 for the synthesis of ZnO/NiFe2O4. • Nanocomposites was characterized using different analytical tools
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    Enhancing Fusarium oxysporum tolerance in Phaseolus vulgaris: Isolation and characterization of bacterial endophytes
    (Elsevier B.V., 2025) Holman, Darin Edward; Keyster, Marshall; Klein, Ashwil; Daniel, Augustine Innalegwu
    Research surrounding microbial biocontrol has garnered considerable attention in the last few years due to the numerous advantages as opposed to synthetic agrochemicals. Phaseolus vulgaris is an important legume that is cultivated worldwide, especially in third-world countries. The growth and yield of this crop are often severely limited by the pathogen Fusarium oxysporum. The aim of the study is to investigate the biological control potential of six plant bacterial isolates against F. oxysporum, both in vitro and in vivo. Six bacterial endophytes were isolated from Ledebouria ovatifolia leaves (E1), Solanum dulcamara leaves (E2), Cortalaria retusa leaves (E3), Euphorbia prostrata roots (R1), Solanum nigrum roots (R2), and Helichrysum splendidum roots (R3). These isolates were characterized for any biocontrol activity they might have against F. oxysporum PPR1. Isolation, characterization, identification, and biocontrol antagonistic assays were carried out in vitro against F. oxysporum, following standard protocols. The isolates were identified using 16S rRNA gene PCR sequencing. A phylogenetic analysis indicated that the leaf isolates displayed a close relationship with Bacillus altitudinis (E1), Streptomyces bikiensis strain SBM (E2), and Pseudomonas rhodesiae (E3). Root isolates displayed a close relationship with Enterobacter kobei (R1), Enterobacter sp. (R2), and Pseudomonas sp. strain (R3). Five out of the six isolates exhibited catalase activity and zinc solubilization activity, whereas all isolates exhibited siderophore production activity. Most of the tested isolates were able to produce the extracellular hydrolytic enzymes protease and amylase. The isolates exhibiting the highest hydrolytic enzyme activities were able to significantly inhibit F. oxysporum growth in vitro. E. kobei exhibited the most promising plant growth-promoting activity, hydrolytic enzyme activity, F. oxysporum antagonism, and increased seedling growth of P. vulgaris. These results suggest that E. kobei represents a good biocontrol candidate against F. oxysporum. The ability of this bacterial isolate to colonize and its promising biological activities suggest it has enormous potential to be used as both a biopesticide and plant growth stimulator.