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Browsing Microbiology -Scholarly Publications by Author "Aboaba, O. O."
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- ItemOpen AccessAntibiotic resistant profiles of food (fresh raw milk) and environmental (abattoir effluents) isolates of Listeria monocytogenes from the six zones of Nigeria(African Journal of Microbiology Research, 2013-08-06) Enurah, L. U.; Aboaba, O. O.; Nwachukwu, S.C.U.; Nwosuh, C. I.The prevalence of Listeria monocytogenes in fresh raw milk and abattoir effluents in the six zones of Nigeria was determined. Antibiotic resistant profile of the isolates was examined using the Bauer- Kirby disc diffusion assay. A total of 626 food and environmental samples were cultured on selective media out of which 54 (8.6%) were positive for L. monocytogenes. Chloramphenicol was the most effective antibiotic against the isolates with the least resistance (3.70%) while nalidixic acid proved to be least effective with resistance of 90.74%. The multiple-antibiotic resistant pattern of the isolates showed nalidixic acid/cloxacillin (35.2%), nalidixic acid/colistin (31.5%) and cloxacillin/colistin/nalidixic acid (29.6%) to be most prominent. The least value was observed in chloramphenicol/nitrofurantin/cotrimoxazole with 5.6%. The modal values of the minimum inhibitory concentrations (MICs) of the antibiotics to the isolates range between 4.0 and >16.0 μg/ml. Chloramphenicol, nitrofurantin and gentamycin recorded the highest MIC compared with other antibiotics. This study has demonstrated that a wide and rapidly expanding range of undesirable and, in some cases, multi-resistant determinants is currently present in L. monocytogenes
- ItemOpen AccessAntimicrobial activities of some Nigerian spices on some pathogens(AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA, 2011-01-01) Aboaba, O. O.; Ezeh, A. R.; Anabuike, C. L.The aqueous and ethanol extracts of four spices ( Monodora myristica, Piper guineense, Xylopia aethiopica, Tetrapleura tetraptera ) were prepared and the antibacterial properties assessed using the agar diffusion method. The test organisms were Enterohaemorrhagic E.coli, Shigella, Salmonella, Klebsiella, Pseudomonas, Klebsiella pnemonium, Staphylococcus aureus, Staphylococcus aureus (ATCC 25923), Bacillus sp. and Enterococcus faecalis. The susceptibility of the test bacteria strains to various antibiotics was performed. The aqueous extracts had antimicrobial activities on all test organisms used (MIC values of 30-60mg/ml and a range of inhibition, 10-25mm). The ethanol extracts were less sensitive (3.3-26mg/ml on E. feacalis). The phytochemical screening of the potent extracts revealed the presence of terpenoids, flavonoid and glycosides. The test organisms showed susceptibility to majority of the antibiotics used ranging from an average of 10mm-37mm. The aqueous extracts can be used as an alternative therapy to the use of antibiotics as the zones of inhibition exhibited by the test strains to both were comparable.
- ItemOpen AccessAntimicrobial Susceptibilities of Salmonellae Isolated from Food Handlers and Cattle in Lagos, Nigeria(2009-03-09) Smith, S. I.; Bamidele, M.; Goodluck, H. A.; Fowora, M. N.; Omonigbehin, E. A.; Opere, B. O.; Aboaba, O. O.Purpose: Food handlers play an important role in the transmission of typhoid bacilli and other Salmonella spp. This study was conducted to determine the prevalence and antimicrobial resistance patterns of Salmonella spp. from food handlers and cattle and compare the patterns with specimens from patients. Methods: A total of 206 stool samples from apparently healthy food handlers from bukkas (cafeteria) and 100 stool samples from cattle were collected in Lagos Metropolis between June 2006 and June 2007. The prevalence and susceptibility patterns of the S. typhi isolates from the samples and those obtained from the stool samples of 27 patients were determined. Results: Salmonella species isolated from the stool samples collected from food handlers were S. typhi, S. enteritidis, S. choleraesuis, S. paratyphi A and S. arizona with prevalence of 6.8%, 5.3%, 2.9%, 1.5% and 0.5%, respectively. S. enteritidis and S. typhimurium were isolated from 100 faecal cattle samples with prevalence of 12% and 3%, respectively. Nearly all the isolates (including the clinical isolates) were sensitive to nitrofurantoin, nalidixic acid, and ofloxacin, while all were sensitive to ciprofloxacin. Conclusion: Food handlers working in bukkas (cafeteria) and cattle are possible reservoirs of Salmonalle species in Lagos. Other than fluoroquinolones, Salmonalle species exhibit high levels of resistance to most antibiotics.
- ItemOpen AccessApplication of Candida valida as a protein supplement(Journal of Food Safety, 2010-03-28) Kuforiji, O. O.; Aboaba, O. O.An investigation was carried out on the carbon and nitrogen sources needed for the growth of a yeast, Candida valida (syn. Candida mycoderma), isolated from Ogi, a fermented edible corn product given to babies at weaning. The suitability of this organism as a protein supplement in foods was also determined. The yeast was grown in different carbon sources: glucose, fructose, lactose, maltose, starch, dextrin, mannitol and ethanol, and in different nitrogen sources like urea, amino acids, ammonium nitrate, sodium nitrate and ammonium sulfate, as part of the synthetic basal medium for 7 days and the growth measured using the dry weight method. A significantly high increase in yield was observed when 1% fructose was used and maximum yield was obtained with 3.5 and 0.2% (w/v) of fructose and urea as carbon and nitrogen sources, respectively. Growing the fungus in 0.3% cane molasses, a natural substrate gave a significantly higher increase in yield than in a synthetic medium. As a food supplement, other nutrient contents of this organism such as ash, crude fiber, lipids and carbohydrates were also analyzed in addition to the protein, free amino acids and energy values
- ItemOpen AccessBiocontrol of Fusarium wilt of cucumber with Trichoderma longibrachiatum NGJ167 (Rifai)(British Microbiology Research Journal, 2016-08-26) Kareem, T. K.; Ugoji, E. O.; Aboaba, O. O.Aim: This research investigated the use of Trichoderma longibrachiatum NGJ167 (Rifai) as a biocontrol agent of Fusarium wilt in cucumber varieties (Ashley and Marketmoor) both in the screenhouse and on the field. Study Design: The screenhouse experiment was laid down in a Completely Randomized Design (CRD) while Randomized complete block design (RCBD) was used for the field experiment. Place and Duration of Study: The study was conducted at the National Horticultural Research Institute, Ibadan between 2012 and 2013. Methodology: Soils were inoculated with mycelial plugs of T. longibrachiatum NGJ167 before planting while the control soil was mock-inoculated with agar plugs of Potato dextrose agar (PDA). Two weeks after planting, F. oxysporum was inoculated into the soils in the screenhouse while natural infection was allowed to occur on the field. The biocontrol abilities of T. longibrachiatum NGJ167 on F. oxysporum was observed on disease incidence and severity and the fruit yield. The presence of T. longibrachiatum NGJ167 genes was detected in the treated cucumber fruits to ensure consumers’ safety. Results: The control plants had higher incidence and severity of F. oxysporum than the T. longibrachiatum-treated plants. The T. longibrachiatum NGJ167-inoculated Marketmoor had higher fruit weight value of 200g in the screenhouse when compared with the control which had a fruit weight value of 133.33 g. On the field, T. longibrachiatum-treated Marketmoor produced the highest fruit weight of 220 g while the control had a mean weight of 120.6 g. Results also revealed that T. longibrachiatum DNAs were absent in the inoculated cucumber fruits. Conclusion: The use of T. longibrachiatum NGJ167 as a biocontrol agent indicates its potentials in improving plant health in agriculture. The absence of T. longibrachiatum NGJ167 in the treated cucumber indicated that the consumption of such fruits will have no adverse effect on consumers’ health.
- ItemOpen AccessBIOLOGICAL SYNTHESIS OF COPPER NANOPARTICLES AND ITS ANTIMICROBIAL POTENTIAL ON SELECTED BACTERIA FOOD-BORNE PATHOGENS(Ife Journal of Science, 2020-12-28) Aderolu, H. A.; Aboaba, O. O.; Aderolu, A. Z.; Abdulwahab, K. O.; Suliman, A. A.; Emmanuel, U. C.In this study, copper nanoparticle (CuNPs) was synthesized using green technology and the CuNPs was characterized with Energy Dispersive X-ray (EDX) which confirmed the presence of copper. Scanning Electron Microscopy (SEM) showed the morphology and the average size was calculated to be 2.47 ± 1 nm. The functional groups were identified by Fourier transform infrared spectroscopy (FTIR) and this revealed that OH functional group was anchored on the surface of the nanoparticles. Antimicrobial activity of the synthesized CuNPs was investigated at varying concentrations (0.25, 0.5, 1, 2, 3, 4, 5, 6 and 7 mg/ml) dissolved in 100% dimethyl sulfoxide (DMSO). It was tested against five food borne pathogenic organisms: Salmonella typhimurium, Methicillin resistant Staphylococcus aureus (MRSA), Enterococcus faecalis, Shigella flexneri, and Acinetobacter baumannii using the Kirby Bauer disc diffusion and agar well method. The results showed that the antimicrobial zone of inhibition increased with an increase in concentration of the CuNPs, an average diameter of 25 mm at 7 mg/ml, 22 mm at 5 mg/ml and an average diameter of 13 mm at 2 mg/ml of 100% DMSO. Nanoparticles at 0.25 mg/ml and 0.5 mg/ml concentration failed to produce any clear zone across all the test organisms while only Enterococcus faecalis was sensitive with a clear zone diameter of 10 mm at 1 mg/ml CuNPs. MRSA has the least susceptibility: 9 mm clear zone diameter at 2 mg/ml and at 7 mg/ml clear zone diameter of 20 mm, relative to other tested organisms. The test organisms were not sensitive to the following conventional antibiotics: Cefuroxime, Ceftazidime, Erythromycin, Amoxicillin/Clavulanic acid and Cloxacillin, but only sensitive to Gentamicin, Ceftriaxone and Ofloxacin. MRSA on the other hand was not sensitive to all the eight antibiotics tested but susceptible to the CuNPs. The results obtained from this study indicated that copper nanoparticles can be used in the food industry to control both Gram positive and negative bacteria tested.
- ItemOpen AccessDetection of plasmid in Listeria monocytogenes isolated from fresh raw milk in Nigeria(Animal and Veterinary Sciences, 2014-10-30) Enurah, L. U.; Aboaba, O. O.; Nwachukwu, S.C.U.; Smith, S. I.; Fowora, M.N.Aims: To determine the presence of plasmids in Listeria monocytogenes strains isolated from fresh raw milk from healthy cattle in Nigeria and also determine its role in antibiotics resistance since this organism is a food borne pathogen of public health importance. Methods and results: Isolation of Listeria monocytogenes was done using selective enrichment and isolation protocol, as recommended by United States Department of Agriculture (USDA) and Association of Analytical Chemists/ International Dairy Federation (AOAC/ IDF). Identification was by phenotypic characterization and confirmed using β-haemolytic activity, phosphatidyl inositol phospholipase-C (PIPLC) assay and polymerase chain reaction (PCR) . Strains identified as Listeria monocytogenes from the six zones were determined and results expressed as rate of prevalence in graph. Twenty-three strains of Listeria monocytogenes isolated from 305 samples of fresh raw milk were screened for the presence of plasmid DNA using the method of Ehrenfeld and Clewel and agarose gel electrophoresis. One isolate was found to harbour one plasmid with molecular weight of 14.62kb. The plasmid was cured using different concentrations of acridine orange. Antibiotic sensitivity test was carried out on both the wild strain (with plasmid) and cured strain using disc diffusion method of Bauer-Kirby and it was found that the wild strain was resistant to seven of the twelve antibiotics used while the cured strain was resistant to only one. Conclusions: There is a possibility of the presence of strains of Listeria monocytogenes that can harbour plasmids. This could confer antibiotic resistance to the strains and thus make antibiotic therapy unsuccessful. The increase in the number of antibiotics which the cured strain of Listeria monocytogenes was susceptible to in this study showed that plasmid may play a significant role in antibiotics resistance. The Fulani herdsmen who take fresh raw milk without boiling or pasteurization may serve as carriers of resistant strains of Listeria monocytogenes and help in its spread in the environment through faecal pollution.
- ItemOpen AccessDETERMINATION OF THE PHYLOGENETIC RELATEDNESS OF CRONOBACTER SPP. ISOLATED FROM POWDERED INFANT FORMULA RETAILED IN NIGERIA USING PAN–GENOMIC DNA MICROARRAY(International Journal of Research, 2018-07-23) Ezeh, A. R.; Tall, B. D.; Gangiredla, J.; Smith, S. I.; Aboaba, O. O.Cronobacter spp. are emerging, opportunistic, food-borne pathogens associated with infections like meningitis, necrotizing enterocolitis and septicaemia in premature and immunocompromised neonates and infants. The phylogenetic relatedness of three Cronobacter species isolated from powdered infant formula retailed in Nigeria was carried out using a Pan-Genomic DNA Microarray constituting 19,287 independent genes representing 15 Cronobacter genomes and 18 plasmids and 2,371 virulence genes of phylogenetically related Gram-negative bacteria. The hybridization results showed that Cronobacter malonaticus (CS14) and Cronobacter sakazakii (CS17 and CS124) clustered with powdered infant formula environmental and clinical strains of C. malonaticus and C. sakazakii isolated from countries like Jordan, Czech Republic, Ireland and USA with a significant relatedness greater than 80%. The sequence types of C. malonaticus CS14 was ST303 and C. sakakakii CS17 and CS124 were ST304 and ST296, respectively. Some virulence genes (integrase of Shigella flexnerri bacteriophage X, hypothetical protein z1655, dihydrofolate reductase, and formate acetyltransferase 1) were detected in CS124 and CS17. Adequate regulatory measures should be applied to monitor imported and locally produced powdered infant formulae to prevent contamination with Cronobacter spp. and other food borne pathogens to ensure the safety of vulnerable neonates and infants
- ItemOpen AccessEffect of incorporation of potassium bromate in commercial wheat flour on the proximate composition, storage stability and consumer acceptability of bread(Bioscience Research Communications, Klobex Academic Publishers, 1999-10-10) Aboaba, O. O.; Bakare, K. O.The effect of incorporation of potassium bromate (KBrO3) in commercial wheat flour on the nutritive value, consumer acceptability and storage stability of bread was investigated. The presence of this chemical at various concentrations of 0.8g/kg, 0.16g/kg and 0.32g/kg had no significant effect on the nutritive value of the flour or the baked product. It could also not improve its storage stability which was better controlled by the storage temperature. However, the baked products from flours with the potassium bromate had improved loaf size, crust colour, crust texture and aroma, and were preferred by consumers
- ItemOpen AccessThe effect of inoculum size on the lag phase of Listeria monocytogenes(International Journal of Food Microbiology, 2001-05-16) Robinson, T. P.; Aboaba, O. O.; Kolati, A.; Ocio, M. J.; Baranyi, J; Mackey, B. M.The effect of inoculum size on population lag times of Listeria monocytogenes was investigated using the Bioscreen automated microtitre plate incubator and reader. Under optimum conditions, lag times were little affected by inoculum size and there was little variation between replicate inocula even at very low cell numbers. However, in media containing inhibitory concentrations of NaCl, both the mean lag time and variation between replicate inocula increased as the inoculum size became smaller. The variation in lag time of cells within a population was investigated in more detail by measuring the distribution of detection times from 64 replicate inocula containing only one or two cells capable of initiating growth. The variance of the lag time distribution increased with increasing salt concentration and was greater in exponential than in stationary phase inocula. The number of cells required to initiate growth increased from one cell under optimum conditions to 105 cells in medium with 1.8 M NaCl. The addition of spent medium from a stationary phase culture reduced the variance and decreased lag times. The ability to initiate growth under severe salt stress appears to depend on the presence of a resistant sub-fraction of the population, although high cell densities assist adaptation of those resistant cells to the unfavourable growth conditions by some unspecified medium conditioning effect. These results are relevant to the prediction of lag times and probability of growth from low numbers of stressed cells in food.
- ItemOpen AccessThe emulsifying effect of biosurfactants produced by food spoilage organisms in Nigeria(International Journal of Food Studies, 2016-04-18) Ogunmola, C. O.; Aboaba, O. O.Food spoilage organisms were isolated using standard procedures on Nutrient Agar, Cetrimide Agar and Pseudomonas Agar Base (supplemented with CFC). The samples were categorized as animal products (raw sh, egg, raw chicken, corned beef, pasteurized milk) and plant products (vegetable salad, water leaf (Talinium triangulare), boiled rice, tomatoes and pumpkin leaf (Teifairia occidentalis). They were characterised as Pseudomonas putida, Pseudomonas aeruginosa, Pseudomonas stutzeri, Burkholderia pseudomallei, Serratia rubidaea, Corynebacterium pilosum, Bacillus subtilis, Bacillus mycoides, Bacillus laterosporus, Bacillus laterosporus, Serratia marcescens, Bacillus cereus, Bacillus macerans, Alcaligenes faecalis and Alcaligenes eutrophus. Preliminary screening for biosurfactant production was done using red blood haemolysis test and con rmed by slide test, drop collapse and oil spreading assay. The biosurfactant produced was puri ed using acetone and the composition determined initially using Molisch's test, thin layer chromatography and gas chromatography mass spectrometry. The components were found to be ethanol, amino acids, butoxyacetic acid, hexade- canoic acid, oleic acid, lauryl peroxide, octadecanoic acid and phthalic acid. The producing organisms grew readily on several hydrocarbons such as crude oil, diesel oil and aviation fuel when used as sole carbon sources. The puri ed biosurfactants produced were able to cause emulsi cation of kerosene (19.71-27.14%) as well as vegetable oil (16.91-28.12%) based on the emulsi cation index. This result suggests that the isolates can be an asset and further work can exploit their optimal potential in industries.
- ItemOpen AccessEstimation of Nutritive Value, Organoleptic Properties and Consumer Acceptability of Fermented Cereal Gruel (OGI)(Advance Journal of Food Science and Technology, 2012-02-15) Opere, B. O.; Aboaba, O. O.; Ugoji, E. O.; Iwalokun, B. A.A gruel, locally called Ogi in Nigeria and prepared by bacterial fermentation from cereals such as maize (Zea mays) and (Sorghum bicolor) of the Poaeceae Gramineae family remain a major source of calorie, nutrient and probiotic factors in human diets in many West African countries including Nigeria. Therefore, knowledge on nutritive, organoleptic and safety values of OGI is hugely essential to justify its dietary utilization and fortification as weaning diets and staples and the need for improvement in cereal fermentation. In this study, we determined the indices of nutrition, palatability and preservation in Ogi made from cultivars of maize and sorghum in Nigeria using Lactobacillus pentosus and L. acidophilus as starter cultures during fermentation. Eleven cultivars of corn and sorghum sold in Nigerian markets were used for the preparation of fermented gruels using L. pentosus and L. acidophilus as single and mixed starter cultures. Gruels from these cultivars were also prepared under uncontrolled fermentation conditions and used as control. These gruels were compared by proximate composition, probiotic and organaoleptic values using standard chemical, chromatographic and spectrophotometric methods. The biochemical analysis of the fermented samples showed the concentration of acid, acetoin and diacetyl to increase in comparison to the controls indicating improved organoleptic properties. All samples showed increased levels of reducing sugars, proteins, and amino acids. Essential amino acids, lysine, isoleucine, and arginine were elicited in all fermented samples, showing desirable nutritional status. All these fermented samples exhibited some degree of inhibition on all the test bacterial cultures. The mixed culture fermented samples had higher values than the single culture fermented samples for all parameters tested indicating higher efficacy
- ItemOpen AccessEstimation of Shelf Life for Water-based Paints Using Regression Methods(Journal of American Science, 2010-01-01) Obidi, O. F.; Nwachukwu, S.C.U.; Aboaba, O. O.; Nwalor, J. U.The shelf lives of water-based paints made in Nigeria were investigated. The mean changes in the microbial population count of six freshly made paint samples (PS1 – PS6) were monitored fortnightly for a period of 10 months. The growth data of isolated organisms from the fresh and spoilt paint samples were fitted into a multiple linear regression model to predict shelf life for the fresh paint samples. The microbial population ranged from 1.0 x 101 – 4.7 x 105 cfu/ml and from 1.0 x 101 – 5.5 x 103 cfu/ml for bacteria and fungi over the study period. Physico-chemical parameters such as specific gravity (SG), optical density (OD), transmittance (TR), pH and viscosity (VIS) were also determined every two weeks for the fresh paint samples over the ten-month study period. The measurements of the physico-chemical parameters suggested deterioration related to microbial population count of the paint samples. Consequently, the model developed comprised of two equations with particular attention to microbial population count and physico-chemical parameters of the paint samples. The microbial population counts of the spoilt paint samples were 3.4 x 1010 cfu/ml and 3.2 x 105 cfu/ml for bacteria and fungi respectively. The changes in the physico-chemical parameters ranged from 2.8658 – 1.0853, 1.49 – 3.91, 6.9 – 2.3, 8.5 – 5.6, 11.7cst –10.8cst for SG, OD, TR, pH and VIS in fresh paint samples. The percentage residual error between the shelf life predicted and the shelf life experimental ranged between 0.001 and 0.500. The shelf lives obtained for the fresh paint samples were 19, 21, 23, 22, 37, and 22 months respectively.
- ItemOpen AccessEvaluation Of Bioremediation Of Agricultural Soils Polluted With Crude Oil By Planting Beans Seeds, Phaseolus Vulgaris(Nature and Science, 2007-01-01) Aboaba, O. A.; Aboaba, O. O.; Nwachukwu, N. C.; Chukwu, E. E.; Nwachukwu, S.C.U.The impact of crude oil on agricultural land, germination, growth and morphology of beans seeds (Phaseolus vulgaris) after bioremediation of agricultural soils polluted with crude oil using selected strains of Pseudomonas putida (PP) was investigated (E). A similar polluted agricultural soil not inoculated with PP served as a control (C). In e, the residual oil concentration decreased from 0.260 at week zero to 0.002g/g soil at week 10 representing about 92% oil reduction. The corresponding values for c were 0.240 and 0.170g/g soil respectively and this is equivalent to about 17% oil reduction. The levels of oil reduction in both E and C were confirmed by the results of gas liquid chromatography which revealed smaller peaks for E. At day 16 during germination experiments, there was 40% germination in E and 20% in C. For C, the mean seedlings height was 5.20 cm and all displayed abnormal morphology such as stunted growth and chlorosis. Thus treatment of oil-polluted agricultural land with PP culture as bioremediating agent can produce soils which can grow healthier plants than where bioremediation has not taken place. In conclusion, beans seeds germination and the general morphology of the seedlings seem to be reliable biological indices for the evaluation of the recovery of crude oil-impacted land after bioremediation protocols using selected microorganisms.
- ItemOpen AccessGrowth Limiting pH, Water Activity, and Temperature for Neurotoxigenic Strains of Clostridium butyricum(Hindawi Publishing Corporation, 2013-08-25) Ghoddusi, H. B.; Sherburn, R. E.; Aboaba, O. O.Some rare strains of Clostridium butyricum carry the gene encoding the botulinal type E neurotoxin and must be considered as possible hazards in certain types of food. The limiting growth conditions for C. butyricum were determined in peptone yeast glucose starch (PYGS) broth incubated anaerobically at 30∘C for up to 42 days. The minimum pH values permitting growth depended on the acidulant and strain. Organic acids were more effective at inhibiting growth than HCl as expected. The lowest pH values at which growth of toxigenic and nontoxigenic strains of C. butyricum was observed in broth acidified with HCl were 4.1 and 4.2, respectively. In organic acids, however, the minimum pH varied between 4.4 and 5.1 depending on acid type and concentration. The minimum water activity for growth of toxigenic strains of C. butyricum was 0.96. The minimum growth temperatures of the toxigenic strains of C. butyricum (ca 10-11∘C) were somewhat higher than for non-toxigenic ones (8∘C). It was concluded that control of toxigenic C. butyricum in the food industry needs to allow for the greater pH tolerance of this species compared with proteolytic C. botulinum.
- ItemOpen AccessHISTOPATHOLOGICAL CHANGES IN THE LIVER OF MICE CHALLENGED WITH Listeria monocytogenes IN SIX ZONES OF NIGERIA(Journal of Experimental Biology and Agricultural Sciences, 2013-11-15) Enurah, L. U.; Aboaba, O. O.; Nwachukwu, S.C.U.; Nwosuh, C. I.Fifty four strains of Listeria monocytogenes were isolated from fresh raw milk and abattoir effluent. Uniform distribution pattern of the isolates in the six zones of Nigeria viz Southwest, Southeast, Southsouth, Norhwest, Northeast and Northcentral is evidence that food contamination with this organism may be a source of foodborne outbreaks in Nigeria. Present study investigated the pathogenic nature of the strains. The pathogenic strains were isolated by culturing on 7% Sheep Blood Agar for evidence of haemolysis and were used to challenge three out of four groups of laboratory bred mice for pathogenicity test. The Group 1 mice were given 1ml of sterile distilled water orally and served as control, groups 2, 3 and 4 with 1.6 x 105cfu/ml orally, subcutaneously and intraperitoneally respectively. Experimental animals were successfully observed up to six days for clinical signs and possible mortality. All the infected mice that died were subjected to post-mortem examination which showed change with liver abscess with congested gall bladder containing purulent bile. Histopathology sections of the liver showed hepatocyte necrosis with infiltration of degenerative neutrophils, lymphocytes and few plasma cells compared to control. The study confirmed the presence of pathogenic strains of L. monocytogenes in all zones of Nigeria and their presence in the food may pose serious health hazards.
- ItemOpen AccessInvestigation on the Biodegradative Potential of Pseudomonas aeruginosa on Water-based Paints(Researcher, 2010-01-10) Obidi, O. F.; Nwachukwu, S.C.U.; Aboaba, O. O.A strain of Pseudomonas aeruginosa (OB-6) isolated from biodeteriorated water-based paint samples was screened for its plasmid profiles and antimicrobial susceptibility patterns. The organism possessed two plasmids which ranged in molecular sizes from 0.030 to 0.112 kilobases (kb). Antimicrobial resistance patterns showed resistance to Tobramycin, Amikacin, Gentamycine and industrial biocides ZN467 and ZN489. After curing experiments with 0.002% (v/v) sodium dodecyl sulphate (SDS), the organism was observed to have lost the two plasmids and the resistance to Tobramycin, Amikacin and Gentamycin. The organism therefore, seemed to bear plasmids that encoded genes for deterioration and antibiotic resistance as determined by the curing experiments. A comparison of the biodegradative potential of the wild and the cured strain on the physico-chemical properties of fresh, sterile paints showed the wild strain to have 25% degradative potential, while the cured strain had 17% degradative potential.
- ItemOpen AccessIsolation and PCR Detection of Cronobacter sakazakii from Powdered Infant Formulae retailed in Nigeria(American Journal of Food and Nutrition, 2013-01-01) Ezeh, R. A.; Aboaba, O. O.; Smith, S. I.; Fesobi, W. A.; Omonigbehin, E. A.; Bamidele, M.The presence of Cronobacter sakazakii in 154 samples of powdered infant formulae (PIF) retailed in Nigeria was analyzed using real time polymerase chain reaction (PCR) and a chromogenic medium, Druggan-Forsythe-Iversen (DFI) agar. Two pairs of species specific primers (SG-F/SG-R and SI-F/SI-R) targeting the sequences between 16S rDNA and 23S rDNA (internal transcribed spacer, ITS) were used for the amplification. Out of the 154 samples analyzed, C. sakazakii was detected in 3 (1.95%). A particular isolate detected by SI primer was not detected by SG primer. This study shows that Cronobacter sakazakii can be detected using both the chromogenic DFI agar (cultural method) and molecular method. This report is the first for the isolation and molecular detection of Cronobacter sakazakii from powdered infant formulae retailed in Nigeria.
- ItemOpen AccessThe leavening ability of baker’s yeast on dough prepared with composite flour (wheat/cassava)(African Journal of Food Science, 2009-09-07) Aboaba, O. O.; Obakpolor, E. A.The leavening ability of baker’s yeast on dough prepared with composite flour (wheat/cassava) was investigated. The composite flour was prepared in four different proportions and it was discovered that an increase in the quantity of cassava flour caused a decrease in the ability of the baker’s yeast to leaven the dough. However, the composite flour with 10% cassava flour produced an appreciable level of leavening. The effect of temperature on leavening of the composite dough by the baker’s yeast was also investigated. It was found that fermentation of dough at 37ºC increased the rate of leavening and an appreciable level of dough size was achieved. The degree of agitation/mixing and the time used for the composite dough was investigated and it was found that longer periods of agitation in minutes produced increased level of dough. The results from the sensory evaluation showed that the bread baked with 10% composite dough was the most acceptable by the panelists. There was no disparity in the scores given to the samples based on age, as the three different age groups gave similar results
- ItemOpen AccessMolecular typing of Salmonella spp isolated from food handlers and animals in Nigeria(International Journal of Molecular Epidemiology and Genetics, 2011-01-01) Smith, S. I.; Fowora, M. N.; Goodluck, H. A.; Nwaokorie, F. O.; Aboaba, O. O.A total of 61 isolates of Salmonella spp (made up of 26 clinical isolates and 20 food handler and 15 animal isolates) were typed by RAPD-PCR for the purpose of screening for epidemiologically related isolates. The RAPD -PCR typing method used comprised six primers namely 787, 797, 784, 1254, RAPD 1 and RAPD 2 but 784 and 1254 did not produce discriminatory patterns and so were dropped. From the 61 strains, RAPD fingerprinting with primers RAPD 1, 2 produced 22 and 24 fingerprint patterns respectively. RAPD fingerprinting with primers 787, 797 produced 17, 11 fingerprinting patterns respectively. Combinations of the two RAPD 1 and 2 primers increased the discrimination of Salmonella strains to 32 patterns rather than the other primers used. Primer 797 was the least discriminatory. This study showed that the RAPD 1 and 2 primers would be useful for epidemiological typing of the Salmonella spp in Nigeria.