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Articles by M.G. Ekpenyong
Total Records ( 3 ) for M.G. Ekpenyong
  M.G. Ekpenyong and S.P. Antai
  Bacillus sp. -02 and Bacillus sp. -12 produced Optical Density (OD) readings of 1.228 and 0.540 , respectively at 540 nm wavelength during screen tests in crude oil/mineral salts broth medium. In addition, both organisms caused extensive shredding (breakdown) of the overlaid oil in tubes indicating oil utilization. Gravimetric measurement of hydrocarbonoclastic potentials of the organisms revealed that such potentials were similar in both species (49.8 and 48.6% weight losses , respectively). Carbon dioxide evolution studies under the influences of cadmium toxicity at concentrations of 1, 10, 100 and 1000 mg L-1 and pH changes from 5.5 through 7.0 to 8.5, revealed that Bacillus sp. -12 produced higher amounts of CO2 and was less sensitive to cadmium toxicity and pH changes during the process than Bacillus sp.-02. This shows that Bacillus sp.-12 would be useful in the bioremediation of petroleum-polluted environments co-contaminated with cadmium in the Niger Delta region of Nigeria.
  M.G. Ekpenyong , S.P. Antai , J.P. Essien and G.D. Iwatt
  The influence of pH (5.5, 7.0 and 8.5) on the response patterns of species of Penicillium and Rhodotorula to increasing concentrations of zinc during biodegradation of Nigerian light crude oil was assessed by the carbon dioxide (CO2) evolution technique, over a 16-day period. Mean rates of CO2 evolution decreased with increasing pH in control cultures of Penicillium sp., but increased with increasing pH in cultures containing 1000 mg L-1 of zinc. However, analysis of variance of data revealed that there was no statistically significant (p>0.05) difference among the metal concentrations, suggesting tolerance of this species of Penicillium to high levels of zinc. In contrast, mean rates of CO2 evolved in cultures containing Rhodotorula sp. decreased with increasing pH in both control and test cultures containing zinc. Efficiency of inhibition was minimal at pH 8.5 in cultures containing Penicillium sp., but maximal at the same pH in those containing Rhodotorula sp. Interestingly, low concentrations of zinc (≤10 mg L-1) stimulated CO2 evolution in Rhodotorula sp. at pH 5.5 and 7.0, but not 8.5, suggesting pH-dependent low level zinc requirement of the oil biodegradative enzymes of the organism.
  M.G. Ekpenyong , S.P. Antai and J.P. Essien
  The number (quantity) and nature (quality) of hydrocarbon-degrading bacteria and fungi in Qua Iboe estuary, Nigeria and their biodegradation potentials were assessed in this study to ascertain the estuary’s inherent capacity for natural attenuation following an oil spill. Water and sediment samples collected 9 months after a minor oil spill revealed, upon analysis that the fraction of total heterotrophic microorganisms that could utilize crude oil as sole source of carbon and energy was up to 64% in sediments and 15% in near shore waters. There was significant correlation (r = 0.78; p<0.05) between total hydrocarbon content (THC) and percentage abundance of hydrocarbon utilizers in the samples. Different taxonomic and physiological groups of bacteria, yeast and mold were identified. Their carbon dioxide evolution potentials as groups, in terms of rate and extent of evolution, were only marginally better than those from their constituent pure culture studies. A pH-dependent periodic succession of these groups and their species was observed during the study. From the foregoing therefore, Qua Iboe estuary has a great capacity to self-purify in the event of an oil spill and such natural attenuation might even be more environment-friendly than other remediation protocols particularly bioaugmentation.
 
 
 
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