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Articles by A.A. Osuntoki
Total Records ( 5 ) for A.A. Osuntoki
  A.A. Osuntoki , O.R. Ejide and E.A. Omonigbehin
  In order to reduce the incidence of foodborne disease which constitutes a major public health problem, we are focussing our attention on the exploitation of indigenous food grade lactic acid bacteria to improve the safety and hygiene of fermented products. In this study we isolated lactobacilli from four fermented dairy products and screened them for the production of antimicrobial substances by eliminating the effects of organic acids and hydrogen peroxide. Three foodborne bacterial pathogens, enterotoxigenic Escherichia coli (ETEC), Salmonella typhimurium and Listeria monocytogenes were used as indicators. Of the twelve Lactobacillus isolates obtained, six showed antagonistic effects against at least one of the pathogens. Three of the twelve isolates (one with detectable antimicrobial activity and two without) were found to harbour plasmids. Plasmid elimination by curing with ethidium bromide revealed no association between the antimicrobial activity and the plasmids. With these results it may be assumed that the antimicrobial effects of these isolates on the pathogens investigated were determined by their chromosomes. In conclusion we have identified indigenous strains of food grade lactobacilli with antimicrobial activity against clinically important bacterial enteropathogens.
  O.D. Olukanni , A.A. Osuntoki and G.O. Gbenle
  Bacterial degradation is a viable treatment option for azo dyes containing wastewater. However, a great drawback is the generation of potentially toxic and mutagenic end products (aromatic amines) by anaerobic bacteria. This study is part of efforts to develop textile effluent bio-treatment processes to produce reusable water by decolourization and degradation of azo dyes to non toxic metabolites. The ability of fourteen bacterial strains isolated from various environmental sources to decolourize textile wastewaters aerobically using a simulated effluent made with three textile reactive azo dyes; Reactive Yellow 42 (RY 42), Reactive Blue 13 (RB 13) and Reactive Red 58 (RR 58) were investigated. Three strains showed >95% decolourization of the synthetic effluent within 24 h. The effect of culture condition (pH, temperature and media) on the degradation of methyl red, a standard azo dye, by the isolate with the highest decolourization level; identified as Micrococcus sp., was also studied. The strain showed optimum decolourization at pH and temperature around 7 and 37°C, respectively. It preferred nutrient broth to minimal media and 0.02 g dry mass decolourized 50 mL, 56 mg L-1 solution of methyl red within 6 h under adequate oxygen supply. UV-visible spectra analyses of aniline sulphate (an aromatic amine) and those of the metabolic products of methyl red suggest that methyl red was first converted to aromatic amine(s) which was subsequently mineralized by the bacterium. The high azo dyes decolorization ability of the Micrococcus strain suggested that aerobic decolourization of azo dyes could be as effective as the anaerobic counterpart if suitable organisms are employed.
  M.N. Igwo-Ezikpe , O.G. Gbenle , M.O. Ilori , J. Okpuzor and A.A. Osuntoki
  The experiment was conducted to evaluate the potential of tropical bacterial isolates and its consortium to biodegrade mixture of high molecular weight polycyclic aromatic hydrocarbons (chrysene, fluoranthene and pyrene). The effect of phenanthrene in the degradation was also investigated. The bacterial consortium was made up of Sphingomonas sp., Pseudomonas sp. and P. putida and biodegradation set up for 8 days with initial 100 mg L-1 substrate concentration. Degradation by Sphingomonas sp., Pseudomonas sp. and P. putida, respectively after 8 days gave higher residual chrysene of 40.2±1.4, 40.3±2.2 and 27.4±1.8 mg L-1, fluoranthene of 32.5±1.3, 35.4±1.2 and 10.1±2.5 mg L-1 and pyrene of 37.5±1.2, 34.2±2.4 and 32.0±1.2 mg L-1 compared to 11.5±1.4 (chrysene), 6.2±1.3 (fluoranthene) and 6.0±1.8 (pyrene) mg L-1 obtained using the bacterial consortium. When the media was supplemented with 100 mg L-1 phenanthrene, after 8 days of degradation by bacterial consortium residual chrysene, fluoranthene and pyrene was 0.45±0.25, 0.02±0.02 and 0.20±0.14 mg L-1, respectively while phenanthrene was undetectable. No statistical significant (p < 0.05) difference was obtained between degradation by bacterial consortium and consortium via co-metabolism with phenanthrene rather they had a strong correlation of r = 0.99. The results suggest that bacterial consortium may be useful for the decontamination of sites polluted with high molecular weight polycyclic aromatic hydrocarbons due to synergistic effect.
  M.N. Igwo-Ezikpe , O.G. Gbenle , M.O. Ilori , J. Okpuzor and A.A. Osuntoki
  Bacteria isolated from various contaminated soils in Nigeria were investigated for their potential to utilize and biodegrade high molecular weight polycyclic aromatic hydrocarbons which include chrysene, fluoranthene and pyrene. Biochemical and morphological studies identified the isolates as Sphingomonas sp., Pseudomonas sp. and Pseudomonas putida. Biodegradation studies showed that Sphingomonas sp., Pseudomonas sp. and P. putida degraded 100 mg L-1 chrysene to 30.5±0.3, 40.6±0.7 and 17.2±0.2 mg L-1, respectively after 8 days of incubation. Similarly, fluoranthene was degraded to 2.0±0.1, 2.0±0.4 and 0.12±0.1 mg L-1 while pyrene to 0.16±0.2, 6.5±0.3 and 6.6±0.4 mg L-1 correspondingly. Consortium of the isolates degraded 100 mg L-1 chrysene, fluoranthene and pyrene, respectively to 21.3±0.9, 2.2±0.8 and 10.6±0.8 mg L-1. In the presence of phenanthrene as co-substrate, chrysene, fluoranthene and pyrene were, respectively degraded by consortium to 12.4±0.5, 0.2±0.3 and 0.7±0.2 mg L-1 while phenanthrene was undetectable. This study showed that there was delayed degradation of chrysene and fluoranthene in the presence of phenanthrene, this may account for the persistence of these compounds in polycyclic aromatic hydrocarbons polluted sites. This is the first report on the potential of these isolates simultaneous utilization and biodegradation of chrysene, fluoranthene and pyrene when used as sole carbon and energy source.
  M.N. Igwo-Ezikpe , O.G. Gbenle , M.O. Ilori , J. Okpuzor and A.A. Osuntoki
  Alcaligenes faecalis was evaluated for its potential to degrade varying concentrations of chrysene and diesel oil with concomitant biosurfactant production. Biodegradation was set up for 7 days utilizing the substrates as sole carbon and energy sources. Residual chrysene obtained after degradation of 30, 50 and 100 mg L-1, respectively was 17.4±1.5, 27.2±1.2 and 28.7±1.4 mg L-1 while total petroleum hydrocarbon remaining after degradation of 3, 5, 15 and 30% (v/v) diesel oil respectively was 2.58±0.5, 3.09±1.2, 21.65±5.4 and 63.92±8.1%. Microbial cells of A. faecalis and sterilized cell-free extract from diesel oil media showed emulsifying activities against kerosene, diesel oil, engine oil, hexadecane, dodecane, xylene and hexane whereas no emulsifying activity was observed of microbial cells and sterilized cell-free extract from chrysene media. Alcaligenes faecalis cells harvested from diesel oil media also showed haemolytic activity unlike the microbial cells from chrysene media. Growth of the isolate in chrysene and diesel oil media induced secretion of protein and carbohydrate into the media which were statistically significantly (p<0.05) different compared to controls. This study portrays the potential of Alcaligenes faecalis to degrade and grow on chrysene and diesel oil and induce extracellular protein and carbohydrate with concomitant production of biosurfactant for industrial purposes and in hydrocarbon bioremediation.
 
 
 
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