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Browsing by Author "Oyetibo, Ganiyu O."

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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.
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, Ginro
A 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.
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.
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.
Biotechnological remedies for the estuarine environment polluted with heavy metals and persistent organic pollutants
(Elsevier, 2017-04-01) Oyetibo, Ganiyu O.; Miyauchi, Keisuke; Huang, Yi; Chien, Mei-Fang; Ilori, Matthew O.; Amund, Olukayode O.; Endo, Ginro
Estuaries in the areas prone to anthropogenic activities are exposed to multifarious pollutants. Toxic concentrations of heavy metals do exist with persistent organic compounds in such estuaries prolonging the recalcitrance and ecotoxicological consequences of the chemicals, which impact on the health of the brackish water and by extension, the oceans. The quest for high aesthetic quality of the estuarine environment is gaining attention from global campaign, which requires effective remedial strategies to replace the physical and chemical methods in use that are costly and often leave behind toxic residues in the environment. Contrary to physico-chemical remedial processes, bioremediation strategies are projected as a promising green technology to remove pollutants from the estuarine environment. The concept of bioremediation involves the use of competent biological elements such as microorganisms and plants, along with or without the biomolecules they produced, to ameliorate pollution. Therefore, this paper reviews the various bioremediation technologies that would be applicable to decommissioning estuarine environments polluted with toxic metals and persistent organic compounds.
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.
Comparative geochemical evaluation of toxic metals pollution and bacterial communities of industrial effluent tributary and a receiving estuary in Nigeria
(Pergamon, 2019-07-01) Oyetibo, Ganiyu O.; Miyauchi, Keisuke; Huang, Yi; Ikeda-Ohtsubo, Wakako; Chien, Mei-Fang; Ilori, Matthew O.; Amund, Olukayode O.; Endo, Ginro
Toxic metals/metalloid contaminations of estuarine sediments due to compromised tributaries arouse significant interest in studying bacterial community that triggers natural attenuation processes. Geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and Hakanson potential ecological risk index (RI) as a sum of risk factors (Er) were used to quantify toxic metal/metalloid-pollution status of Lagos Lagoon (2W) and ‘Iya-Alaro’ tributary (4W) sediments in comparison with pristine ‘Lekki Conservation Centre’ sediment (L1-B). Bacteriology of the ecosystems was based on culture-independent analyses using pyrosequencing. 2W and 4W were extremely contaminated with mercury (Igeo > 7), whereas, cadmium contamination was only observed in 4W. The two ecosystems were polluted with toxic metal based on PLI, where mercury (Er = 2900 and 1900 for 4W and 2W, respectively) posed very high ecological risks. Molecular fingerprinting revealed that Proteobacteria, Firmicutes, and Acidobacteria predominately contributed the 20 most abundant genera in the two ecosystems. The 240 and 310 species present in 2W and 4W, respectively, but absent in L1-B, thrive under the metal concentrations in the polluted hydrosphere. Whereas, the 58,000 species missing in 2W and 4W but found in L1-B would serve as indicators for systems impacted with metal eco-toxicity. Despite toxic metal pollution of the ecosystems understudied, bacterial communities play vital roles in self-recovery processes occurring in the hydrosphere.
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.
Ecological risk potentials of petroleum hydrocarbons and heavy metals shape the bacterial communities of marine hydrosphere at Atlantic Ocean, Atlas Cove, Nigeria
(Elsevier Journal of Environmental Management, 2021-04-03) Oyetibo, Ganiyu O.; Ige, Oluwatobi O.; Obinani, Peace K.; Amund, Olukayode O.
Trans-Atlantic voyage of petroleum often leads to marine pollution with petroleum hydrocarbons (PHs) and heavy metals (HMs) that defines structures of autochthonous bacteria in the hydrosphere. Bacterial taxa of marine sediments exposed to petroleum transport activities were profiled using 16S rDNA metagenomics and correlated with the geochemistry to establish their impact on the microbiome. The physico-chemistry of the marine systems revealed varied degrees of contamination with PHs and HMs exceeding recommended threshold for aquatic life. Ecological risk assessment based on organic carbon of the sediment established phenanthrene, anthracene, and pyrene posed high risks (index risk quotient >32) to marine life. The most dominant phylum of the 44 bacterial phyla in the marine-sphere was Proteobacteria with relative abundance of 45–77% in the sampling locations. Relative dominance of Proteobacteria in the sediments spanned Gammaproteobacteria (17–25%), Deltaproteobacteria (12–20%), and Alphaproteobacteria (7–14%). Whereas, more operational taxo- nomic units (OTUs) belonging to Epsilonproteobacteria (19 ± 2.4%) were found in estuarine sediment unlike < 0.5% relative abundances obtained from oceanic sediments. Sulfurimonas apparently dominated the bacterial genera with up to 2.16 ± 0.19% abundance in oceanic sediments. Canonical correspondence analysis revealed that PHs shaped the structure of bacterial OTUs in oceanic sediments where petroleum loading/offloading occurs unlike in some kilometres a yonder where HMs correlated with the bacteria structure. The dominant bacteria might possibly pivotal to ecophysiologies of hydrocarbon contaminated marine environment, and would be pertinent to biotechnological applications for possible bioremediation campaign.
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.
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 pollution
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.
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.
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.
Microbial population changes in tropical agricultural soil experimentally contaminated with crude petroleum
(Academic Journals, 2008-11-17) Obayori, Oluwafemi S.; Ilori, Matthew O.; Adebusoye, Sunday A.; Amund, Olukayode O.; Oyetibo, Ganiyu O.
Impacts of crude petroleum pollution on the soil environment and microbial population dynamics as well as recovery rates of an abandoned farmland was monitored for seven months spanning the two major seasons in Nigeria with a view to establishing process conditions necessary for development of effective strategies for bioremediation. The physico-chemistry of the control and contaminated soils differed just significantly (P < 0.05). Whereas these factors were relatively stable over the period of investigation for the control site, a downward trend was observed for the experimental. The polluted soil showed significant diversity in structure and number of flora .There was an initial drop in microbial population densities at the onset of pollution but, a gradual increase was observed thereafter. Higher counts of microflora were obtained for April, May, June and July samples which coincided with the onset and peak of wet season. A rapid and significant reduction in residual oil concentration was observed during this period. Overall, nearly 100% of the crude oil pollutant was degraded within the 28- week study period. The residual oil concentration gave a high but negative correlation coefficient (r = - 0.84 to -0.90) with total heterotrophic and hydrocarbon-utilizing populations. On application of data generated to model equations, approximately 60.5 weeks would elapse before the contaminated soil could recover from the impact of the oil. Our results show that a natural population readily able to degrade crude oil is present in the soil chosen for this study. However, it may be necessary to monitor the level of inorganic nutrients and adjust some appropriately to enhance biodegradation of the organic pollutant.
Pyrene-degradation Potentials of Pseudomonas Species Isolated from Polluted Soils
(Springer Netherlands, 2008-07-04) Obayori, Oluwafemi S.; Ilori, Matthew O.; Adebusoye, Sunday A.; Oyetibo, Ganiyu O.; Amund, Olukayode O.
Three Pseudomonas species isolated from oil polluted soil in Lagos, Nigeria were studied for their pyrene degradation potentials. These isolates exhibited broad substrate specificities for hydrocarbon substrates including polycyclic aromatic hydrocarbons, petroleum fractions and chlorobenzoates. All three isolates tolerated salt concentrations of more than 3%. They resisted ampicillin, cenfuroxime, but susceptible to ofloxacin and ciprofloxacin. Pseudomonas sp. Strain LPl exhibited growth rates and pyrene degradation rates of 0.018 h-1 and 0.111 mg l-1 h-1 respectively, while P. aeruginosa strains LP5 and LP6 had corresponding values of 0.024, 0.082 and 0.017, 0.067 respectively. The overall respective percentage removal of pyrene obtained for strains LPl had the highest uptake rate. Strains LPl, LP5, and LP6 also used the ortho-cleavage pathway. Enzyme study confirmed activity of catechol 1,2-dioxygenase in all with values 0.6823,0.9199, and 0.8344 umol min-1 mg-1 respectively for LP1, LP3 and LP6. To the best of our knowledge, ours is the first report of pyrene-degraders from the sub-Saharan African environment.
Taxonomic profiling of bacteria and fungi in freshwater sewer receiving hospital wastewater
(Elsevier, 2021) Ogwugwa, Vincent H.; Oyetibo, Ganiyu O.; Amund, Olukayode O.
Consistent discharges of hospital wastewaters (HWWs) pose ecological risk to the biome of the receiving environment with cumulative effect on its healthiness. Understanding the taxonomic profile of microorganisms in the impacted systems is required to establish taxa that are bio-indicators of toxicants, and provide possible taxa for mitigating ecotoxicity of the HWWs. Geochemistry, pollution status and ecotoxicity of heavy metals (HMs) in HWW-impacted sewer (LU) were assessed. The microbiome profiling was based on 16S rDNA and ITS of 18S rDNA metagenomes. The degree of HMs contamination exceeded 50 and HMs pollution load index of LU was severe (1,084), which consequently exerted severe risk (1,411,575 toxic response factors) with very high toxic responses of Co, Cu, Pb, and Cd. Eco-toxicological impact of the HMs on LU skewed microbiome towards Proteobacteria (43%), Actinobacteria (18%), and about 5% apiece for Chloroflexi, Acidobacteria, Plantomycetes, and Bacteroidetes. Likewise, the relative abundance of in LU inclined towards Ascomycota (59%), Basidiomycota (17%) and unclassified Eukarya_uc_p (16%). Exclusively found in LU sediments were 44,862 bacterial species and 42,881 fungi taxa, while 72,877 and 53,971 species of bacteria and fungi, respectively, were found missing. Extinction and emergence of bacteria and fungi taxa in LU were in response to HMs ecotoxicity and the need for natural attenuation processes respectively. The profiled taxa in LU may be plausible in bioremediation strategies of the impacted system, and in designing knowledge-based bioreactor system for the treatment of HWWs before discharge into the environment.

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