Microbiology -Scholarly Publications
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Browsing Microbiology -Scholarly Publications by Author "Aboaba, O.O."
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- ItemOpen AccessAntibacterial Effect of Edible Plant Extract on Escherichia coli 0157:H7(Pakistan Journal of Nutrition, Asian Network for Scientific Information, 2006-01-01) Aboaba, O.O.; Smith, S. I.; Olude, F. O.Sixteen preparation of the ethanol and aqueous extracts of four edible plants, Entada africana (bark),Terminalia avicennoides (bark),Mitragyna stipulosa (bark) Lannae acida (stem bark) were screened for their inhibitory effects on ten strains of E coli 0157:H7 (EHEC) using the agar diffusion method. It was shown that ethanol extracts of Entanda africana inhibited all the ten strains used, some extracts showed variable antibacterial activities while some others could not cause any inhibition. The minimum inhibitory concentration (MIC) of the potent extracts ranged from 1.56mg/ml to 50.00mg/ml while the minimum bacteriocidal concentration (MBC) was between 6.25mg/ml to 25.00mg/ml. Pytochemical screening of the extracts revealed that all contained saponin. Some showed presence of tannins and glycosides while alkaloid was not detected in all samples.
- ItemOpen AccessThe effect of inoculum size and sublethal injury on the ability of Listeria monocytogenes to initiate growth under suboptimal conditions(Letters in Applied Microbiology, 2001-08-22) Pascual, C.; Robinson, T. P.; Ocio, M. J.; Aboaba, O.O.; Mackey, B. M.Aims: To investigate the effect of inoculum size and physiological state on the ability of Listeria monocytogenes cells to initiate growth under suboptimal conditions of salt concentration and pH. Methods and Results: Cell suspensions were serially diluted in media of different salt concentration or pH and replicate inocula distributed into 96-well microplates. The proportion of wells showing growth at each dilution level was determined after incubation for 6 weeks for each set of conditions. Growth occurred from single cells up to a concentration of 1á2 mol l)1 NaCl; above this threshold, the inoculum size needed to initiate growth became progressively larger. A similar effect was seen with decreasing pH but only very close to the growth/no growth boundary. The threshold for inoculum-dependent growth was lower in exponential phase cells than in stationary phase ones and sublethal injury greatly decreased the probability of growth from small inocula. Conclusions: The growth/no growth boundary for L. monocytogenes is not an absolute cut-off point but represents a region where the probability of growth rapidly decreases as conditions become more extreme. We interpret the requirement for a critical inoculum size for growth as being due to death of a proportion of cells in the inoculum rather than to co-operative population effects. Signi®cance and Impact of the Study: Physiological heterogeneity within the cell population and inoculum size will affect the risk of L. monocytogenes growing in food.
- ItemOpen AccessEnvironmental impact on the bacteriological quality of domestic water supplies in Lagos, Nigeria(Revista de Saúde Pública, 2002-04-04) Egwari, L.; Aboaba, O.O.Objective To assess the impact of town planning, infrastructure, sanitation and rainfall on the bacteriological quality of domestic water supplies. Methods Water samples obtained from deep and shallow wells, boreholes and public taps were cultured to determine the most probable number of Escherichia coli and total coliform using the multiple tube technique. Presence of enteric pathogens was detected using selective and differential media. Samples were collected during both periods of heavy and low rainfall and from municipalities that are unique with respect to infrastructure planning, town planning and sanitation. Results Contamination of treated and pipe distributed water was related with distance of the collection point from a utility station. Faults in pipelines increased the rate of contamination (p<0.5) and this occurred mostly in densely populated areas with dilapidated infrastructure. Wastewater from drains was the main source of contamination of pipe-borne water. Shallow wells were more contaminated than deep wells and boreholes and contamination was higher during period of heavy rainfall (p<0.05). E. coli and enteric pathogens were isolated from contaminated supplies. Conclusions Poor town planning, dilapidated infrastructure and indiscriminate siting of wells and boreholes contributed to the low bacteriological quality of domestic water supplies. Rainfall accentuated the impact.
- ItemOpen AccessGrowth studies of Pseudomonas fluorescens implicated in soft rot of purple variety of Onions in Southern Nigeria(Nature and Science, 2007-01-01) Aboaba, O.O.This is the growth studies of Pseudomonas fluorescens implicated in soft rot of purple variety of Onions in Southern Nigeria. As the conclusion, the initiation and development of rot can be prevented by controlling the temperature and relative humidity of the storage environment as well as reducing general inoculation level through adequate sanitary practices during storage and handling.
- ItemOpen AccessInorganic Nutrient Ion (PO43-, NO-3 and SO42-) as Essential Requirements in Bioremediation of soils polluted with Crude Petroleum(Nigerian Journal of Microbiology, 2016) Obidi, O.F.; Alo, M.N.; Nwachukwu, S.C.U.; Aboaba, O.O.The recovery rate of oil impacted agricultural soils by joint application of biostimulation agents such as PO43- and NO-3 (inorganic nutrient ions) and Bacillus subtilis (BS) as a bioaugmentation agent was investigated for 12 weeks. The dissolved oxygen (DO), pH, inorganic nutrient ions by ion chromatography and residual oil content by a gravimetric method, were determined over the period, as well as the microbial population density (MPD) by standard plate count (SPC). MPD enumerated for both the experimental (EDS) and the control (CDS) between weeks 2 and 7 showed increasing trends with the corresponding decreases in the oil content, particularly in EDS inoculated with BS. However, at week 8, PO43- and NO-3 depleted appreciably from 346 and 807 to 24 and 375 ppm respectively and simultaneously with a rapid decrease in MPD particularly the hydrocarbon utilizers (HCU). This apparently indicated the importance of nutrient ions in the bioremediation of oil polluted environments. The pH and DO values consistently decreased in both EDS and CDS over period. The result of this study showed that biostimulationinvolving inorganic nutrients adjustment and bioaugmentation by application of BS were the two key factors responsible for the remarkable differences in the results obtained for EDS particularly in the rapid oil content reduction when comared with CDS
- ItemOpen AccessMicrobiological and Physico-chemical Evaluation of Some Non-alcoholic Beverages(Pakistan Journal of Nutrition, Asian Network for Scientific Information, 2004-01-01) Osuntogun, B.; Aboaba, O.O.The microbial and physico-chemical quality of our commercially produced non-alcoholic beverages-Ginger beer, Soya milk, Soborodo drink and kunun-zaki-were investigated. The organisms isolated included lactic acid bacteria like Lactobacillus, Streptococcus and Leuconostoc. Other bacterial isolates were Staphylococcus, Bacillus and Pseudomonas while the fungi were Penicillium, Aspergillus, Trichoderma, Candida and Saccharomyces. Studies were also carried out on the sensory evaluation and shelf-stability during storage. A combination of pasteurization and refrigeration was found most suitable for prolonged shelf life and consumer acceptability. Chemical analysis showed that the major food components were retained, though some toxic elements were detected like Cadmium and-Chromium even above the permissible levels.
- ItemOpen AccessOccurence of Camplyobacter species in poultry forms in Lagos area of Nigeria(Journal of Environmental Biology, 2004-10-05) Smith, S. I.; Aboaba, O.O.Samples of poultry droppings were collected from fifty poultry farms in Lagos area of Nigeria. Campylobacter species were isolated from serially diluted samples using Bolton selective enrichment medium under microaerophilic condition at 42 degrees C. Samples of water, both treated and untreated used in the farms were also analysed in the same manner. Fifteen Campylobacter strains were isolated from the droppings. All the strains were identified using biochemical characteristics differentiating Campylobacter species. They were identified as hippurate positive (C. jejuni) and negative species (C. coli). They were biotype' using the extended scheme described by Lior (1984). Campylobacter coli biotype 'I was the most prevalent (66.66%) followed by C. jejuni biotype 1 (20.00%). The biotype ii of the two species accounted for 6.67% each. The C. jejuni biotype III and IV were not isolated during the study. The preponderance of C. coli indicates that poultry can be a major reservoir for the spread of human campylobacteriosis. Poultry farmers, therefore, must ensure prompt and adequate means of disposal of waste materials as well as maintaining good sanitary conditions
- ItemOpen AccessPlasmid profile of Escherichia coli 0157:H7 from apparently healthy animals(African Journal of Biotechnology, 2003-08-22) Smith, S. I.; Aboaba, O.O.; Odeigha, P.; Shodipo, K.; Adeyeye, J. A.; Ibrahim, A.; Adebiyi, T.; Onibokun, H.; Odunukwe, N. N.One hundred samples from healthy animals were screened for the presence of enterohaemorrhagic Escherichia coli 0157: H7 and 17 were positive for EHEC 0157:H7 after confirmation using serology kits. Antibiotic susceptibility patterns showed the isolates to be highly susceptible to the various antibiotics screened with a few showing multiple antibiotic resistance. The plasmid profiles revealed that 8/17 (47%) of the animal isolates harboured detectable plasmids ranging in size from 0.564 kb to >23 kb.