Microbiology -Scholarly Publications
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Browsing Microbiology -Scholarly Publications by Author "Adebusoye, S.A."
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- ItemOpen AccessBacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian Contaminated Systems(2009) Oyetibo, G.O.; Ilori, M.O; Adebusoye, S.A.; Obayori, O.S.; Amund, O.OSamples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd2+,Co2+,Ni2+,Cr6+,and Hg2+)were isolated from the samples,and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations(MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted.Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd2+,15 mM for Co2+and Ni2+,17 mM for Cr6+, and 10 mM for Hg2+. Five strains(Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni2+,P. aeruginosa resisted 10 mM Co2+. To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.
- ItemOpen AccessComparative Study of Biosurfactant Synthesis by Pseudomonas aeruginosa isolated from Clinical and Environmental Samples.(2012) Agwu, O.; Ilori, M.O; Adebusoye, S.A.; Amund, O.OEvaluation of emulsifying activities indicates that biosurfactants were produced by an environmental (strain EPl) and a clinical (strain EPl) species of Pseudomonas aeruginosa. During growth on hydrocarbons, the organisms produced biosurfactants. Both strains grew luxuriantly on motor oil and readily synthesized abundant surfactants at the expense of easily metabolizable substrates. During a12 day cultivation on motor oil, the organisms produced growth associated extracellular surfactants with emulsification activities of 71 and 38% for EPl and CPl, respectively. The general times obtained for EPl and CPl were 1.74 and 2.66 days. The biosurfactants that could not be secreted on glucose were partially purified and putatively identified as rhamnolipids. The surface-active compounds present high emulsification activity and stability in the pH range of 3.0-10.0, temperature range of 4oC-100oC, and salinity range of 16 -44% and are capable of stabilizing oil-in-water emulsions with several hydrocarbons. Typical emulsions produced were stable for several weeks. The results also showed that the biosurfactants were able to remove a significant amount of crude oil from contaminated soil; for instance, strain EPl surfactant removed 54%, CPl 41%, detergent 42%, and water 30%. The rhamnolipids from these strains represent a new class of biosurfactants that have potential for use in a variety of biotechnological and industrial applications where extremes of pH, thermal, and saline conditions would have little or no effect on activity.
- ItemOpen AccessExtensive biodegradation of Nigerian Crude Oil (Escravos Light) by newly Characterized Yeast Strains.(2011) Ilori, M.O; Adebusoye, S.A.; Obayori, S.O.; Oyetibo, G.O.; Ajidahun, O.; James, C.; Amund, O.OBecause microbial degradation is known to be an efficient process in the in situ decontamination of oil-bearing environments, it is believed that development of effective bioremediation strategies will be aided by microbial sourcing of novel and competent hydrocarbon degraders with a broad and unusual substrate spectrum. Thus, in keeping with this objective, two Candida strains (MNI and MCI) isolated after a repeated batch enrichment technique were tested for their biodegradation potentials on Nigerian crude oil, Escravos light. Axenic cultures of strains MNI and MCI grew at a rate of 1.623 and 0.586 d-1, respectively, in mineral salts medium supplemented with 8.4 g L-1 of crude oil. Whereas strain MNI degraded aliphatic fractions by 97.6% and the aromatics by 74.61%, the corresponding values obtained for MCI were 97.2% and 67.29% during the 14-day incubation period. The gas chromatography (GC) fingerprinting of aliphatic fractions showed major degradation of heptadecane (C17), octadecane (C18), nonadecane (C19), eicosane (C20), undodecane (C21), tricosane (C23), hexacosane (C26), octacosane (C28), and nonacosane (C29) in less than 6 days, whereas nearly 100% of these fractions including the isoprenoid molecules was metabolized in 14 days. Among the aromatic fractions that were nearly eliminated during the cultivation period were naphthalene, phenanthrene, fluoranthrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthrene, and benzo(a)pyrene. Intrestingly, substrate uptake studies showed that both strains grew very well on petroleum cuts, biphenyl, phenol, xylene, and quite a number of polycyclic aromatic hydrocarbons including pyrene, phenanthrene, and anthracene.
- ItemOpen AccessHeavy metals assessment of ecosystem polluted with wastewaters and taxonomic profiling of multi‑resistant bacteria with potential for petroleum hydrocarbon catabolism in nitrogen‑limiting medium(Springer, 2023-01-11) Oyetibo, G.O.; Adebusoye, S.A.; Ilori, M.O.; Amund, O.O.The coexistence of heavy metals (HMs) and petroleum hydrocarbons (PHs) exacerbates ecotoxicity and impair the drivers of eco-functionalities that stimulate essential nutrients for the productivity of the impacted environment. Profiling the bacteria that stem the ecological impact via HMs sequestration and PHs catabolism with nitrogen fixation is imperative to bioremediation of the polluted sites. The sediment of site that was consistently contaminated with industrial wastewaters was analysed for ecological toxicants and the bacterial strains that combined HMs resistance with PHs catabolism in a nitrogen-limiting system were isolated from the sediment and characterized. The geochemistry of the samples revealed the co-occurrence of the above-benchmark concentrations of HMs with the derivatives of hydrocarbons. Notwithstanding, nickel and mercury (with 5% each of the total metal concentrations in the polluted site) exhibited probable effect concentrations on the biota and thus hazardous to the ecosystem. Approx. 31% of the bacterial community, comprising unclassified Planococcaceae, unclassified Bradyrhizobiaceae, Rhodococcus, and Bacillus species, resisted 160 µmol Hg2+ in the nitrogen-limiting system within 24 h post-inoculation. The bacterial strains adopt volatilization, and sometimes in combination with adsorption/bioaccumulation strategies to sequester Hg2+ toxicity while utilizing PHs as sources of carbon and energy. Efficient metabolism of petroleum biomarkers (> 87%) and Hg2+ sequestration (≥ 75% of 40 µmol Hg2+) displayed by the selected bacterial strains portend the potential applicability of the bacilli for biotechnological restoration of the polluted site.