Browsing by Author "Obayori, Oluwafemi S."
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Item Acenaphthene biodegradation and structural and functional metagenomics of the microbial community of an acenaphthene-enriched animal charcoal polluted soil(Biocatalysis and Agricultural Biotechnology, 2021-02) Salam, Lateef B.; Obayori, Oluwafemi S.; Ilori, Mathew O.; Amund, Olukayode O.Animal charcoal from skin and hides cottage industries indiscriminately disposed in run offs and drainage channels harbors hazardous constituents that are mutagenic and toxic, and thus require bio-based ecofriendly depuration strategies. A microbial consortium (FN7) from an animal charcoal polluted site enriched with acenaphthene was structurally and functionally characterized via illumina next generation sequencing and annotation of their putative ORFs, and also studied for ability to degrade acenaphthene. Structurally, FN7 metagenome consists of 7 phyla, 13 classes, 38 orders, 49 families, 67 genera, 68 species, and 45 strains, respectively. The dominant phylum, class, order, family, genus, species, and strain in the metagenome are Proteobacteria (48.9%), Actinobacteria (31.8%), Actinomycetales (28.0%), Enterobacteriaceae (18.9%), Paracoccus (12.9%), Bacillus cereus group (13.5%), and Methylobacterium radiotolerans JCM 2831 (22.4%). The microbial consortium in the metagenome degraded 59.68% (29.84 mg l−1) and 89.16% (44.58 mg l−1) of the initial concentration of acenaphthene (50 mg l−1) in 14 and 21 days. Functional annotation of the putative ORFs of the metagenome using KEGG KofamKOALA, NCBI's conserved domain database, BacMet, and Antibiotic Resistance Gene-ANNOTation (ARG-ANNOT) revealed the detection of hydrocarbon-degradation genes including salicylaldehyde dehydrogenase and catechol 1,2 dioxygenase involved in acenaphthene degradation, resistance genes for mercury, arsenic, cadmium, nickel, and several others, and antibiotic resistance genes for 15 antibiotic classes such as β-lactam, colistin, aminoglycoside, among others. This study revealed that members of FN7 metagenome are equipped with requisite gene batteries and could be veritable bioresources for in vitro biodegradation as well as on-site bioremediation of animal charcoal polluted sites.Item Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian Contaminated Systems.(Springer Netherlands, 2010-09-01) Oyetibo, Ganiyu O.; Ilori, Matthew O.; Adebusoye, Sunday A.; Obayori, Oluwafemi S.; Amund, Olukayode O.Samples 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.Item Biodegradation of anthracene by a novel actinomycete, Microbacterium sp. isolated from tropical hydrocarboncontaminated soil(Springer: World Journal of Microbiology and Biotechnology, 2013-07) Salam, Lateef B.; Obayori, Oluwafemi S.; Olatoye, Nojeem O.A novel anthracene-degrading Gram-positive actinomycete, Microbacterium sp. strain SL10 was isolated from a hydrocarbon-contaminated soil at a mechanical engineering workshop in Lagos, Nigeria. The polluted soil had an unusually high total hydrocarbon content of 157 g/kg and presence of various heavy metals. The isolate tolerated salt concentration of more than 4 %. It resisted cefotaxime, streptomycin and ciprofloxacin, but susceptible to meropenem, linezolid and vancomycin. The isolate exhibited growth rate and doubling time of 0.82 days-1 and 0.84 days, respectively on anthracene. It degraded 57.5 and 90.12 % of anthracene within 12 and 21 days, respectively while the rate of anthracene utilization by the isolate was 4.79 mg l-1 d-1. To the best of our knowledge, this is the first report of isolation and characterization of anthracene-degrading Microbacterium sp.Item Biodegradation of crude oil and phenanthrene by heavy metal resistant Bacillus subtilis isolated from a multi-polluted industrial wastewater creek(Elsevier, 2017-05-01) Oyetibo, Ganiyu O.; Chien, Mei-Fang; Ikeda-Ohtsubo, Wakako; Suzuki, Hitoshi; Obayori, Oluwafemi S.; Adebusoye, Sunday A.; Ilori, Matthew O.; Amund, Olukayode O.; Endo, GinroA critical bottleneck associated with bioremediation technology in multi-polluted environments is microbiostasis due to metal toxicity. Autochthonous Bacillus species that would harness a repertory of traits to catabolize hydrocarbons and simultaneously sequester heavy metals (HMs) is invaluable in the environment contaminated with divergent pollutants. Fourteen HM-resistant bacilli from polluted creek were characterized using phenotypic and molecular criteria, and studied for hydrocarbon degradation in chemically defined media amended with Co2+ and Ni2+ (5.0 mmol l−1 each). Phylogenetic analyses revealed distribution of the bacilli into three clades. Two dissimilar strains of Bacillus subtilis (M16K, and M19F) with 19.1% sequence divergence, exhibited excellent degradation of crude oil (>94.0%) with evidence of early degradation of isoprenoid hydrocarbons and concurrent metal removal 18 d post-inoculation. Similarly, phenanthrene degradation (>85.0%), and corresponding metal detoxification occurred in 28 d axenic culture of the strains. Strain M16K and M19F were metabolically active in matrices containing HMs, degraded hydrocarbons and simultaneously removed HMs from the medium. To the best of our knowledge, this is the first report of metal-resistant Bacillus subtilis strains showing simultaneous degradation of hydrocarbons and detoxification of metals, particularly in the Sub-Saharan Africa. The bacilli could be useful as potential biological agents in effective bioremediation campaign for multi-polluted environments.Item Biodegradation of petroleum hydrocarbons in the presence of nickel and cobalt(Journal of basic microbiology, 2013-11) Oyetibo, Ganiyu O.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Amund, Olukayode O.Bioremediation of environments co-contaminated with hydrocarbons and heavy metals often pose a challenge as heavy metals exert toxicity to existing communities of hydrocarbon degraders. Multi-resistant bacterial strains were studied for ability to degrade hydrocarbons in chemically defined media amended with 5.0 mM Ni2þ, and Co2þ. The bacteria, Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia AL96Co, and Corynebacterium kutscheri FL108Hg, utilized crude oil and anthracene without lag phase at specific growth rate spanning 0.3848–0.8259 per day. The bacterial populations grew in hydrocarbon media amended with nickel (Ni) and cobalt (Co) at 0.8393–1.801 days generation time (period of exponential growth, t ¼ 15 days). The bacteria degraded 96.24–98.97, and 92.94–96.24% of crude oil, and anthracene, respectively, within 30 days without any impedance due to metal toxicity (at 5.0 mM). Rather, there was reduction of Ni and Co concentrations in the axenic culture 30 days post-inoculation to 0.08–0.12 and 0.11– 0.15 mM, respectively. The metabolic functions of the bacteria are active in the presence of toxic metals (Ni and Co) while utilizing petroleum hydrocarbons for increase in biomass. These findings are useful to other baseline studies on decommissioning of sites co-contaminated with hydrocarbons and toxic metals.Item Biodegradation potentials of polyaromatic hydrocarbon (pyrene and phenanthrene) by Proteus mirabilis isolated from an animal charcoal polluted site(Elsevier, 2017-10-01) Obayori, Oluwafemi S.; Salam, Lateef B.; Oyetibo, Ganiyu O.; Idowu, Monsurat; Amund, Olukayode O.Indiscriminate disposal of animal charcoal from skin and hides cottage industries often impact the environments with toxic hydrocarbon components and thus require eco-friendly remedial strategies. A bacterial strain isolated from a site polluted with animal charcoal was characterized, identified as Proteus mirabilis 10c, and studied for ability to degrade pyrene and phenanthrene. The bacterium resisted 30 µg chloramphenicol, 10 µg ampicillin, 30 µg amoxicillin and 10 µg perfloxacin; while it utilized a number of polycyclic aromatic hydrocarbons and cinnamic acid. Specific growth rate on pyrene and phenanthrene were 0.281 d−1 and 0.276 d−1, respectively. Kinetics of degradation of pyrene was 87.92 mg l−1 in 30 days at the rate of 2.93 mg l−1 d−1, biodegradation constant at 0.073 d−1 and half-life of 9.50 d. The corresponding values for phenanthrene degradation kinetics by the bacterium were 90.12 mg l−1, 3.02 mg l−1 d−1, 0.079 d−1 and 8.77 d, respectively. Efficient degradation of crude oil (92.3%) in chemically defined medium was evident with near-disappearance of most aromatic spectra in 30 days. Considering its unique physiologies and broad specificities for aromatic and aliphatic hydrocarbons, the bacterium has potentials for decommissioning environments contaminated with toxic components of animal charcoal.Item Chromium (VI) biosorption properties of multiple resistant bacteria isolated from industrial sewerage(Springer Netherlands, 2013-08-01) Oyetibo, Ganiyu O.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Amund, Olukayode O.Chromium (VI) [Cr (VI)] biosorption by four resistant autochthonous bacterial strains was investigated to determine their potential for use in sustainable marine water-pollution control. Maximum exchange between Cr (VI) ions and protons on the cells surfaces were at 30–35 °C, pH 2.0 and 350–450 mg/L. The bacterial strains effectively removed 79.0–90.5 % Cr (VI) ions from solution. Furthermore, 85.3–93.0 % of Cr (VI) ions were regenerated from the biomasses, and 83.4–91.7 % of the metal was adsorbed when the biomasses was reused. Langmuir isotherm performed better than Freundlich isotherm, depicting that Cr (VI) affinity was in the sequence Rhodococcus sp. AL03Ni > Burkholderia cepacia AL96Co > Corynebacterium kutscheri FL108Hg > Pseudomonas aeruginosa CA207Ni. Biosorption isotherms confirmed that Rhodococcus sp. AL03Ni was a better biosorbent with a maximum uptake of 107.46 mg of Cr (VI) per g (dry weight) of biomass. The results highlight the high potential of the organisms for bacteria-based detoxification of Cr (VI) via biosorption.Item Degradation of hydrocarbons and biosurfactant production by Pseudomonas sp. strain LP1(Springer Netherlands, 2009-09-01) Obayori, Oluwafemi S.; Ilori, Matthew O.; Adebusoye, Sunday A.; Oyetibo, Ganiyu O.; Omotayo, Ayodele E.; Amund, Olukayode O.Pseudomonas sp. strain LP1, an organism isolated on the basis of its ability to grow on pyrene, was assayed for its degradative and biosurfactant production potentials when growing on crude, diesel and engine oils. The isolate exhibited specific growth rate and doubling time of 0.304 days⁻¹ and 2.28 days, respectively on crude oil (Escravos Light). The corresponding values on diesel were 0.233 days⁻¹ and 2.97 days, while on engine oil, were 0.122 days⁻¹ and 5.71 days. The organism did not show significant biosurfactant production towards crude oil and diesel, but readily produced biosurfactant on engine oil. The highest Emulsification index (E₂₄) value for the biosurfactant produced by LP1 on engine oil was 80.33 ± 1.20, on day 8 of incubation. Biosurfactant production was growth-associated. The surface-active compound which exhibited zero saline tolerance had its optimal activity at 50°C and pH 2.0.Item Degradation of polycyclic aromatic hydrocarbons: Role of plasmids(Academic Journals : Scientific Research and Essays, 2010-12-24) Obayori, Oluwafemi S.; Salam, Lateef B.Polycyclic aromatic compounds are a group of highly recalcitrant organic pollutants. The initial steps in the degradation of polycyclic aromatic hydrocarbon (PAHs) involve the dihydroxylation of the aromatic ring, a step catalysed by dioxygenase enzymes. The degradation of many xenobiotic and hydrocarbon compounds is known to be mediated by plasmid encoded enzymes. In this review, an insight is given into the role of plasmid in degradation of PAHs, acquisition of degradative ability by these organisms via horizontal transfer and clustering, resulting from tranposon-mediated recombination. There is preponderance of information showing high level of plasmid involvement in the degradation of naphthalene and other 2- and 3-ring PAHs. Information on higher molecular weight PAHs is however scanty. Recent studies suggest possible involvement of plasmid in HMWPAH degradation than was previously thought. Many plasmids involved in PAH-degradation are megaplasmids, of linear configuration, encoding part or the whole genes for the complete pathways. In recent times, validation of propositions on degradative gene acquisition by horizontal gene transfer (HGT) has been obtained from field studies. HGT and transposition seems to be more chronologically linked and less fortuitously directed than previously thought. Improvement on the methods used in isolation of degraders and study of these is important, towards making a significant stride in elucidating plasmid involvement in PAH degradationItem Degradation of weathered crude oil (Escravos Light) by bacterial strains from hydrocarbons-polluted site(African Journal of Microbiology Research, 2011-06-30) Obayori, Oluwafemi S.; Salam, Lateef B.; Omotoyo, Ibiyemi M.Two hydrocarbon degrading Gram-negative bacteria isolated from hydrocarbon polluted power plant soil in Lagos, Nigeria, were studied for their degradation potentials on weathered crude oil (Escravos Blend). These bacteria isolates were identified as Enterobacter cloacae strain LG1 and Burkholderia cepacia strain LG2. The highest population density for LG1 was 2.07 x 107 cfu/ml, while for LG2 it was 1.63 x 107 cfu/ml. In the two cases slight but consistent pH drops to < 6.51 were observed. LG1 had a growth rate of 0.38 d-1 and doubling time 1.83 d. The corresponding values for LG2 during the first log phase were 0.58 d-1 and 1.19 d, respectively, while in the second log phase the values were 0.14 d-1 and 5.13 d Gas chromatographic analysis showed that chrysene was degraded by LG and LG2 by 92.91 and 80.25%, respectively, anthracene by 92.21 and 91.53%, respectively, and Benzo (b) fluoranthene was degraded by 77.19 and 98.41%, respectively. LG2 had a higher degradative capability of the polyaromatic fractions with 80.15% while LG I was lower at 52.33%. Statistical analysis showed that there was a significant difference (p < 0.05) in the degradation of various aromatic components of the oil by LG1 and LG2.Item Detection of biosynthetic genes of microbially-synthesized secondary metabolites in a contaminated tropical agricultural soil(Springer: Biologia, 2021-08-16) Salam, Lateef B.; Obayori, Oluwafemi S.; Mohammed, Mutiat O.The hunt for microbially-synthesized secondary metabolites have long generate exceptional interest due to their unique functionalities. In this study, shotgun metagenomic was used to decipher the array of secondary metabolites present in a contaminated agricultural soil (AB1) via detection of their biosynthetic genes. Functional annotation of AB1 metagenome’s putative open reading frames (ORFs) for polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs) revealed that majority of the detected biosynthetic genes belong to type I polyketides and non-ribosomal peptides. Biosynthetic genes for type I polyketides such as macrolides, polyene macrolides, rapamycin-related compounds (FK506, FKF20), myxobacterial compounds (epothilone A, soraphen A), lovastatin, enediynes, among others were detected. Similarly, biosynthetic genes for non-ribosomal peptides such as surfactin, fengycin, iturin, lichenysin, arthrofactin, vibriobactin, mycobactin, bacitracin, gramicidin S, viomycin, bleomycin, vancomycin, pristinamycin, tyrocidine, fumiquinazoline and several others were also detected. Taxonomic characterization of the detected biosynthetic genes revealed microorganisms that are not known to be natural producers of the secondary metabolites, thus pointing to the possibility of horizontal gene transfer. The huge repository of these genes in the soil environment is a clear reminder of the pivotal role the soil as a natural resource can play as a source of exciting natural products that can be deployed as viable alternatives to solve myriad of challenges facing the medical, industrial, and environmental settings.Item Effect of Corn Steep liquor on growth rate and Pyrene Degradation by Pseudomonas strain(Springer-Verlag, 2010-06-01) Obayori, Oluwafemi S.; Adebusoye, Sunday A.; Ilori, Matthew O.; Oyetibo, Ganiyu O.; Omotayo, Ayodele E.; Amund, Olukayode O.The growth rates and pyrene degradation rates of Pseudomonas sp. LPl and Pseudomonas aeruginosa LP5 were increased in corn steep liquor (CSL) supplemented. On pyrene alone the higher specific growth rate of LPl was 0.818 h-1, while on CSL-supplemented pyrene MSM, the value was 0.026 h-1. For LP5 the highest growth rate on CSL-supplemented pyrene-MSM was 0.034 h-1. Conversely, on pyrene alone the highest rate was 0.024 h-1. CSL led to marked reduction in residual pyrene. In the case of Pseudomonas sp. LPl values of residual pyrene were 58.54 and 45.47 %, respectively, for the unsupplemented and supplanted both cultures, showing a difference of 13.09 %. For LP5 the corresponding values were 64.01 and 26.96 %, respectively, showing a difference of 37.05 %. The rate of pyrene utilization by LPl were 0.08 and 0.11 mg l-1 h-1 on unsupplemented and supplemented media, respectively. The corresponding values for LP5 were 0.07 and 0.015 mg l-1 h-1, respectively. These results suggest that CSL, a cheap and readily available waste product, could be very useful in the bioremediation of environments contaminated with pyrene.Item Efficiency of cassava steep liquor for bioremediation of diesel oil-contaminated tropical agricultural soil(Springer US, 2010-03-01) Adebusoye, Sunday A.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Oyetibo, Ganiyu O.; Akindele, Kehinde A.; Amund, Olukayode O.Soil artificially contaminated with diesel oil, treated with cassava steep liquor (CSL) and designated EXPS. Similar polluted soil without CSL amendment (CSSl) and uncontaminated soil (CSS2) served as controls. There were dramatic changes in the physic-chemistry of systems EXPS and CSSl with utilization of the inorganic nutrients to near-depletion in the former than the latter. In contrast, the properties of CSS2 remained relatively stable throughout the investigated period. Similarly, the population densities of microflora in the polluted soils showed an initial decrease between days 0 and 5 before assuming an increasing trend with percent hydrocarbon-utilizers ranging significantly (P < 0.05) from 0.56 to 6.6, 0.1 to 2.46 and 0.56 to 0.26, respectively for EXPS, CSSl, and CSS2. In EXPS, the residual oil decreased from 98,045 to 1,102.3 mg/kg soil at day 35 representing about 98.88% degradation. The corresponding value for CSSl was 98,106.1 to 52,110 mg/kg soil, amounting to 46.88% oil disappearance. The GC finger prints of alkane fractions of the recovered oil reduced significantly by day 15 for EXPS with near-similar results of CSSl. However, by day 35, there was complete disappearance of all peaks including the pristane and phytane molecules in the former whereas in CSS1, there were no observable changes. The germination and growth profiles of maize seed plants as evidence of recovery of oil-impacted soils were poor in CSS1 (10%) with pronounced abnormal morphology when compared with the data obtained for EXPS (74%) and CSS2 (80%). These results suggest that CSL could be an indispensable tool in bioremediation of environments contaminated with hydrocarbons. The technology of application is simple, rapid and cost-effective and may be appropriate for use in developing countries to ameliorate the problems of petroleum pollutionItem Enhanced Degradation of Petroleum Hydrocarbons in Corn-Steep-Liquor-Treated Soil Microcosm(Taylor and Francis: Soil and Sediment Contamination: An International Journal, 2015-06) Obayori, Oluwafemi S.; Salam, Lateef B.; Anifowoshe, Wusamot T.; Odunewu, Zainab M.; Amosu, Odunayo E.; Ofulue, Bukola E.The efficiency of corn steep liquor (CSL) as a potential stimulant for remediation of hydrocarbon-contaminated soil was evaluated in soil microcosms. Chronically polluted soil samples treated with CSL, water, and un untreated control were compared over a period of 42 days. There were remarkable changes in the physicochemical status of the soil in the CSL-treated set-up with noticeable utilization of essential nutrients such as nitrogen, phosphorus, and potassium. Percentage hydrocarbon utilizers showed a concomitant increase with hydrocarbon utilization in CSL-treated (0.05–0.16%) and water-treated (0.02–0.12%) set-ups, while no significant changes occurred in the untreated control. Gas chromatographic fingerprints showed complete disappearance of the lower-fraction alkanes C7, C8, C9, and C11 within 21 days, as well as some higher fractions, significantly C16 and C29, in the CSL-treated set-up. In the CSL-treated set-up, 77.9% of hydrocarbon was degraded, while the corresponding values for the water-treated and untreated control were 40.55 and 30.6%, respectively. The percentage aliphatic components degraded differed significantly in the CSL-treated, water-treated, and untreated set-ups. The n- C17/pristane and n-C18/phytane ratios in the CSL-treated set-up were 1.298 and 1.153, respectively, on day 0, but at the end of the treatability period, the values had dropped drastically to 0.182 and 0.585, respectively. The results of this study show that corn steep liquor is a potential material for bioremediation of hydrocarbonpolluted sites.Item Equilibrium studies of cadmium biosorption by presumed non-viable bacterial strains isolated from polluted sites(Elsevier, 2014-07-01) Oyetibo, Ganiyu O.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Amund, Olukayode O.Presumed non-viable high resistant Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia AL96Co, Corynebacterium kutscheri FL108Hg, and Rhodococcus sp AL03Ni were studied for Cd2+ adsorption potentials. Moderate temperature, acidic pH, and high ionic strength were required for bacterial-sorption of cadmium, attaining isothermic equilibrium within 20 min. Experimental cadmium-biosorption data fitted well into biosorption isotherms. The adsorption capacities of the bacterial cell masses spanned 0.003–0.009 l mg−1 (Langmuir model) and 0.43–0.68 (Freundlich model), while binding capacity ranged from 1.14 to 56.16 mg gdw−1, with maximum achievable cadmium uptake of 62.07–109.37 mg gdw−1. The bacteria selectively removed the metal at low concentration (100.0 mg l−1) with an efficiency ranging from 50.0% to 80.0%, while approximately 80.0–92.0% removal efficiency was obtained at higher ionic concentrations (450.0 mg l−1). About 92.66% of the adsorbed metal was recovered from strain CA207Ni upon desorption, and approximately 91.7% of Cd2+ in solution was re-adsorbed onto the biomasses. In this work, effective feasible biosorption of Cd2+ in simulated wastewater system at harsh physico-chemistry, using non-viable resistant bacterial strains was demonstrated. The results indicate that the bacterial strains are sustainable tools for the detoxification of cadmium ions in industrial effluents via wastewater treatment, and cadmium demobilisation in contaminated ecosystem.Item Extensive biodegradation of Nigerian crude oil (Escravos light) by newly characterized yeast strains(Taylor & Francis Group, 2011-09-07) Ilori, Matthew O.; Adebusoye, Sunday A.; Obayori, Oluwafemi S.; Oyetibo, Ganiyu O.; Ajidahun, O.; James, C.; Amund, Olukayode O.Because 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.Item Growth of Pseudomonas aeruginosa LP5 on 2, 5-dicchlorobenzoate: Detection of aromatic ring hydroxylating dioxygenase (ARHDO) gene(Inter Research J Microbiol, 2011) Obayori, Oluwafemi S.; Ilori, Matthew O.; Amund, Olukayode O.Pseudomonas aeruginosa LP5 grew on 2, 5-dichlorobenzoate with doubling time (D) 6.64 d and mean growth rate (k) 0.104 d-1. The organism showed a prolonged lag period lasting 9 days followed by a sudden rise within 3 days (D= 1.1 d; k= 0.628 d-1) and death in less than 72 hours on 2, 6-dichlorobenzoate. Polymerase chain reaction (PCR) amplification of DNA of LP5 showed aromatic dihydroxylating (ARHDO) gene band with molecular weight corresponding to the targeted fragment (0.73 kb). The capability of LP5 on dichlorobenzoates and detection of dioxygenase genes is a validation of its versatility and potential for bioremediation.Item Hydrocarbon Degradation and Biosurfactant Production by an Acenaphthene-degrading Pseudomonas Species(Taylor and Francis: Soil and Sediment Contamination: An International Journal, 2016-08) Salam, Lateef B.; Obayori, Oluwafemi S.; Hawa, ObajeAn acenaphthene-degrading bacterium putatively identified as Pseudomonas sp. strain KR3 and isolated from diesel-contaminated soil in Lagos, Nigeria was investigated for its degradative and biosurfactant production potentials on crude oil. Physicochemical analysis of the sampling site indicates gross pollution of the soil with high hydrocarbon content (2100 mg/kg) and detection of various heavy metals. The isolate grew luxuriantly on crude oil, engine oil and acenaphthene. It was resistant to septrin, amoxicillin and augmentin but was susceptible to pefloxacin, streptomycin and gentamycin. It was also resistant to elevated concentration of heavy metals such as 1–15 mM lead, nickel and molybdenum. On acenaphthene, the isolate exhibited specific growth rate and doubling time of 0.098 day¡1 and 3.06 days, respectively. It degraded 62.44% (31.2 mg/l) and 91.78% (45.89 mg/l) of 50 mg/l acenaphthene within 12 and 21 days. On crude oil, the specific growth rate and doubling time were 0.375 day¡1 and 1.85 days with corresponding percentage degradation of 33.01% (903.99 mg/l) and 87.79% (2403.71 mg/l) of crude oil (2738.16 mg/l) within 9 and 18 days. Gas chromatographic analysis of residual crude oil at the end of 18 days incubation showed significant reductions in the aliphatic, alicyclic and aromatic fractions with complete disappearance of benzene, propylbenzene, pristane, phytane, and nC18-octadecane fractions of the crude oil. The isolate produced growth-associated biosurfactant on crude oil with the highest emulsification index (E24) value of 72% § 0.23 on Day 10 of incubation. The partially purified biosurfactant showed zero tolerance for salinity and had its optimal activity at 27 C and pH 2.0.Item Influence of pH, temperature and nutrient addition on the degradation of atrazine by Nocardioides spp. isolated from agricultural soil in Nigeria.(Malaysian Society for Microbiology, 2016) Omotayo, Ayodele E.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Amund, Olukayode O.Aims: To effectively exploit the atrazine degrading capabilities of Nocardioides spp. isolated from agricultural soil samples in Nigeria and ascertain the effect of pH, temperature and nutrient addition on the degradation process. Methodology and results: Isolates were cultivated on atrazine mineral salts medium at a temperature range of 4 °C - 45 °C and a pH range of 3-10. An optimum atrazine degrading activity was observed in the isolates between temperatures of 25 °C and 37 °C and between pH 5 and 8. Different carbon sources (glycerine, glucose, chitin, cellulose and sodium citrate) and nitrogen sources (urea, biuret, cyanuric acid, potassium nitrate and ammonium chloride) were also added to the medium. The addition of carbon and nitrogen sources did not increase degradation rates although urea and glycerine repressed the degradation ability of the isolates. Statistical analyses of variance at P < 0.05 showed no significant differences in the growth and degradation rates by both bacterial isolates under these conditions. Conclusion, significance and impact study: Atrazine degradation by Nocardioides spp. is pH and temperature dependent, and requires no additional sources of carbon and nitrogen. Hence, its use in bioremediation of atrazine contaminated agricultural soil should be explored.Item Metal biouptake by actively growing cells of metal-tolerant bacterial strains(Springer International Publishing, 2015-08-01) Oyetibo, Ganiyu O.; Ilori, Matthew O.; Obayori, Oluwafemi S.; Amund, Olukayode O.Metal uptake potentials of Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia CA96Co, Rhodococcus sp. AL03Ni, and Corynebacterium kutscheri FL108Hg were studied to determine their competence in detoxification of toxic metals during growth. Metabolism-dependent metal biouptake of the bacteria revealed appreciable uptake of the metals (57–61, 10–30, 23–60, and 10–16 mg g dw−1 of Ni2+, Cr6+, Co2+, and Cd2+, respectively) from medium, after initial drop in pH, without lag phase. The bacteria exhibited 95–100 % removal efficiency for the metals from aqueous medium as 21 (±0.8)–84 (±2.0) concentration factors of the metals were transported into the bacterial systems. Passive adsorption onto the cell surfaces occurred within 2-h contact, and afterwards, there was continuous accumulation for 12 days. Biosorption data of the bacteria were only fitted into Langmuir isotherm model when strains AL96Co, CA207Ni, and AL03Ni interacted with Ni2+, achieving maximum uptake of 9.87, 2.72, and 2.69 mg g dw−1, respectively. This study established that the actively growing bacterial strains displayed, at least, 97.0 % (±1.5) continuous active removals of metals upon adsorption. The bacteria would be good candidates for designing bioreactor useful in the detoxification campaign of heavy metal-polluted systems.