Microbiology
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Item Characteristic properties of derived wort from lactic acid bacteria (LAB) challenged sorghum Samples.(Science domain International, 2016) Afolabi, F. T.; Onilude, A. A."Aim: This study aimed at investigating lactic acid bacteria (LAB) as starter cultures for the improvement of alcoholic beverages. Methodology: Sorghum was obtained from Bodija market and also from the Institute of Agricultural Research and Training, Ibadan. LAB were isolated from spontaneously-fermenting sorghum. The abilities of the LAB strains to produce antimicrobials and their antagonistic activity against known cereal pathogens were used to select the best three strains for further work. The selected strains were applied singly and in combination at inoculum concentration of 2.3 x 104 cells/mL for five days to challenge sorghum seeds prior to malting and wort production. Sorghum wort was fermented for five days with Saccharomyces carlsbergensis. Physiological and nutritional characteristics of the unchallenged and challenged sorghum, and fermentative characteristics of the wort were determined. Results: One hundred and twenty-seven strains of LAB were isolated and identified as L. plantarum (32), L. brevis (31), L. fermentum (25), L. delbrueckii (8), L. casei (12) and L. acidophilus (19). The pH reduced from 6.50+0.03 to 2.93+0.03. L. plantarum (WS) and L. casei (WS) also had the same total residual sugar content with value of 0.97+ 0.03% at day 5. L. plantarum (WS) and L. casei (WS) produced the highest Total titratable acidity (TTA) with values of 4.77+ 0.03% while control (RS) had the least TTA with value of 3.97+0.09%. Control (WS) had the highest protein content of 1.17+0.03%, L. casei (RS) had the least protein content with value of 0.93+0.03%. L. plantarum (WS) had the highest FAN content of 29.97+0.19mg/L while the least Free amino nitrogen (FAN) was produced by control (RS) with value of 19.37+0.07mg/L. Fermentation of the unchallenged wort with pH of 6.2 yielded ethanol content of 2.2 %. The subsequent fermentation produced 4.8 % ethanol. Conclusion: This study demonstrated the use of biological control methods, involving the use of LAB as starter cultures. It improved the quality of the end products in brewing. The use of LAB as starter cultures is an alternative treatment to chemical treatment which can be used to control microbial contamination during sorghum malting."Item Biochemical changes and sensory evaluation of soy iru produced using starter culture(Science Domain international, 2016) Afolabi, F. T.; Abdulkadir, M.Soybean (Glycine max L.) was processed into iru using Bacillus subtilis SBI 13 and Leuconostoc mesenteroides as starter culture and calabash as fermenting container. The fermenting soya beans were analysed for pH and titratable acidity, free amino acids and total soluble sugar. The Enzymatic analysis (protease, amylase and lipase) was also carried out. The combination of Bacillus subtilis and Leuconostoc mesenteroides showed higher protease and amylase activities than when they were used singly. The samples were fermented for 3 days after which were evaluated for sensory qualities. The pH of the samples ranged from 7.08 to 8.88, the titratable acidity ranged from 0.58 to 0.73, the total free amino acids ranged from 1.10 to 6.29% and the total soluble sugar ranged from 18.02 to 29.29%. All the iru samples were acceptable by the sensory panelists but the soy iru fermented with both Bacillus subtilis SBI 13 and Leuconostoc mesenteroides SBI 15 (Bacillus + LAB soy iru) was the most preferred.Item Isolation and screening of microorganisms associated with locust bean (iru) for the ability to ferment soya bean to produce iru(Science Domain international, 2016) Afolabi, F. T.; Abdulkadir, M.; Onilude, A. A."Aims: This study was conducted to isolate, identify and screen microorganisms associated with soy iru for the ability to be used as starter in the fermentation of soya bean (Glycine max) to produce soy iru. Study Design: To control the fermentation of soya bean (Glycine max) to produce soya iru using functional starter culture in order to improve the quality of the product. Place and Duration of Study: Soybeans (Glycine max) samples were collected from markets in Ibadan, in Oyo State Nigeria. Analyses of the samples were conducted in the Department of Microbiology, University of Ibadan and Central Multidisciplinary Research Laboratory in the University of Ibadan, Nigeria. The sampling and analyses were done between August 2014 to January 2015. Methodology: Soybean (Glycine max) seeds were purchased from markets, in Ibadan, Oyo State, Nigeria. Spontaneously fermented locust bean iru samples were also purchased from iru seller from markets, Ibadan, Oyo State and they were analysed using Nutrient agar, DeMann Rogosa and Sharpe medium (MRS), MacConkey Agar and Malt Extract Agar and isolates were also screened for enzymatic activity. The antibacterial activity of LAB metabolites against some indicator organisms was also determined; Results: A total of thirty eight (38) strains of bacteria were isolated, seven (7) isolates from locust bean iru (LBI) and thirty one (31) isolates from soya bean iru (SBI). Bacillus subtilis SBI 13 and Leuconostoc mesenteroides SBI 15 produced the three enzymes and the highest protease activity was produced by Bacillus subtilis SBI 13. All the isolated LAB produced antimicrobial compounds; lactic acid, diacetyl and hydrogen peroxides with Leuconostoc mesenteroides SBI 15 producing the highest quantity of diacetyl (0.91 g/l) and hydrogen peroxide (1.10 g/l) while the highest quantity of lactic acid (1.61 g/l) was produced by Lactobacillus plantarum. Bacillus subtilis SBI 13 and Leuconostoc mesenteroides SBI 15 were chosen as starter cultures for further study. Conclusion: Bacillus subtilis and Leuconostoc mesenteroides exhibit the best potentials of a good starter so they can be used as starter culture in the fermentation of soya beans to produce Soy Iru."Item Effect of lactic cultures on fermented drink produced from sorghum (Sorghum bicolor)(Marsland Press / Zhengzhou University, 2016) Afolabi, F. T.; Onilude, A. A.A total of thirty four lactic acid bacteria (LAB) isolates were isolated from fermented cereal gruels and processed yoghurt and they were identified as Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus bulgaricus. Three of the LAB that produced the highest antimicrobials i.e lactic acid, diacetyl and hydrogen peroxide when the lactic acid bacteria were screened for the production of antimicrobials were selected as starter organisms to treat the germinating sorghum that was used for the drink production. Production of drink was done after the sorghum samples were malted. Proximate analysis which include specific gravity, total protein, viscousity, total sugar, pH, sugar level and colour were also carried out on the sorghum drink. The sample treated with L. plantarum and L. acidophilus had the highest specific gravity of 1.03 and the least was L. brevis 1.02; L.brevis and L. plantarum used for treating sorghum the drink sample produced the highest protein value of 0.62% and L. brevis produced drink with highest viscousity with value of 13.25. The highest sugar was produced by L. acidophilus and L. plantarum treated sample with values of 3.98mg/ml. The pH of the drink were ranged between 3.85 to 4.08. The sugar level was highest with value of 0.25mg/ml in the sample treated with L. brevis. L. acidophilus had the highest effect on the colour of the drink with value of 5.92 with L.brevis being the least with value of 4.82. Analysis of the sensory evaluation results revealed consumer acceptance of the lactic acid bacteria (LAB) treated sorghum drink than the sample not treated with Lactic acid bacteria.Item Therapeutic effect of lactic acid bacteria isolated from freshly-harvested honey and its comb against food and wound- borne pathogens(New Century Health Publishers, LLC, 2016) Adeyemo, S. M.; Afolabi, F. T.; Ogunlusi, E. D.Honey has been extensively studied in the treatment of wounds but its efficacy in clinical practice is not fully understood. Lactic acid bacteria (LAB) have been used as bio-preservative in fermented foods. This work was carried out to evaluate the antagonistic effect of LAB present in fresh honey and its comb against some pathogens. LAB were isolated from five replicate samples of freshly harvested honey and its comb and identified as Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus plantarum and Lactobacillus lactis. Lactic acid, Diacetyl and Hydrogen peroxide (g/l) production were determined for 5 days. L. plantarum and L. brevis exhibited the highest and the lowest antimicrobials production, respectively. Agar well diffusion method was used to monitor the antagonistic activities against some pathogens. L. plantarum and L. brevis gave the highest zones of inhibition ranging from15 23mm on P. aeruginosa and S. aureus from food samples. They compete favourably with standard antibiotics set up as controls. Lactic acid bacteria demonstrated a significant antimicrobial activity; this shows its potential as probiotics in food preservation and its therapeutic effect in wound treatment. This also justifies the efforts directed by individuals in using honey to treat diabetic wounds.Item Candidaemia or candidasis: controversy of staphylococcus sexually transmitted infection?(2016-01) Ogunshe, A. O.Herbal medications are becoming increasingly popular but a most-extraordinary claim by traditional/herbal medical practitioners relates to a Gram-positive bacterium, Staphylococcus, which has been depicted as a deadly sexually transmitted disease that manifest in the form of worms and other symptoms; with contributory roles including infertility, sexual dysfunction and impotency. They further boasted that they are the only ones that possessed the remedy (herbal) for the Staphylococcus sexually transmitted scourge. In the absence of distinguishing phenotypic taxonomic tools, Staphylococcus and Candida spp. may be confused for each other. However, Staphylococcus is a bacterium and not an infection; therefore, there must be more to the traditional medical practitioners’ boasts in ability to cure an infection that was not an infection in the first place. In conclusion, the common sense is that candiaemia or candidiasis is most likely the misdiagnosed sexually transmitted Staphylococcus disease, which is of significant human clinical health issue.Item Candidaemia or candidasis: controversy of staphylococcus sexually transmitted infection?(2016-01) Ogunshe, A. O.Herbal medications are becoming increasingly popular but a most-extraordinary claim by traditional/herbal medical practitioners relates to a Gram-positive bacterium, Staphylococcus, which has been depicted as a deadly sexually transmitted disease that manifest in the form of worms and other symptoms; with contributory roles including infertility, sexual dysfunction and impotency. They further boasted that they are the only ones that possessed the remedy (herbal) for the Staphylococcus sexually transmitted scourge. In the absence of distinguishing phenotypic taxonomic tools, Staphylococcus and Candida spp. may be confused for each other. However, Staphylococcus is a bacterium and not an infection; therefore, there must be more to the traditional medical practitioners’ boasts in ability to cure an infection that was not an infection in the first place. In conclusion, the common sense is that candiaemia or candidiasis is most likely the misdiagnosed sexually transmitted Staphylococcus disease, which is of significant human clinical health issue.Item BIOREMEDIATION OF HEAVY METALS CONTAMINATED SOIL FROM A STEEL ROLLING COMPANY IN IBADAN(2016-06) OYINLOYE, I. A.The accumulation and persistence of Heavy Metals (HMs) in soil poses serious environmental challenges. These HMs may leach and impair surface and ground water quality as well as bioaccumulate in plants. The burden of HMs in the environment can be reduced by Organic Amendment (OA) stimulated bacterial remediation. However, there is dearth of information on the treatment of HMs contaminated soil with OA stimulated microorganisms. This study was designed to bioremediate HMs contaminated soil using cattle dung slurry stimulated bacterial inoculum. Heavy metal contaminated soil samples were purposively collected from the surrounding of a steel rolling mill in Alomaja, Oluyole Local Government Area, Ibadan, Nigeria. Cattle dung slurry used as OA was collected from a commercial animal pen in Bodija Market, Ibadan. Bacteria were isolated from the soil using pour plate agar technique and identified using biochemical and molecular techniques. The isolates were screened to select high HMs tolerant strains used in remediation following standard techniques. The soil and OA samples were analysed for HM and sterilised using appropriate techniques. The sterilised soil was mixed with OA in ratio 5:1 and remediated with selected bacterial strains and thereafter Corchorus olitorius was planted for eight weeks using potted experiment. The experimental set up was completely randomised design of 16 groups consisting of sterilised mixture with three isolates (A, B, and C) singly and in combinations while Sterilised Soil (SS) only and Unsterilised Soil (US) with OA served as controls and each had five replicates. Agronomic parameters (Plant Height (PH), Stem Diameter (SD) and Number of Leaves (NL)) were monitored weekly under screen house conditions for eight weeks. Plants and composite soil for each study group were analysed for HMs thereafter. Data were analysed using descriptive statistics and ANOVA at α0.05. The soil was heavily contaminated with heavy metals, especially lead and chromium with concentrations of 1505.1-2333.6 and 1526.0-1678.7 mg/kg, respectively. Thirty-six bacteria isolates were identified as Pseudomonas (19), Proteus (5), Alcaligenes (5), Enterobacter (3), Providencia (2) and Bacillus (2). Alcaligenes aquatilis (A), Pseudomonas mucidolens (B) and Bacillus cereus (C) had high tolerance for HM (400-450 µg/mL) and were used for remediation. The results obtained for the PH, SD and NL in un-amended soil revealed a significant difference between ABC that had 7.84±0.69 cm, 1.35±0.00 mm, 5.8±0.45 and SS that had 4.10±0.55 cm, 1.33±0.04, 5.0±0.0, respectively. While in OA treated soil, BC had 9.24±1.78 cm, 1.35±0.00 mm, 5.60±0.55 and US had 22.94±4.30 cm, 2.20±0.20 mm and 9.40±1.82 for PH, SD and NL, respectively. Post bioremediation analysis of the soil samples revealed a reduction in the concentration of lead from 2333.55 to 20.8 and 22.6 mg/kg in B and ABC while chromium reduced from 1678.7 to 1.8 mg/kg in B. Postharvest analysis of C. olitorius revealed that percentage crude fibre, dry weight (g), lead and chromium concentration (mg/kg) in ABC and SS were 21.72±0.99, 0.99±0.17; 20.61±0.78, 0.63±0.24; 10.90±0.85, 4.15±0.64 and 9.15±0.64, 4.00±0.14, respectively. Pseudomonas mucidolens effectively remediated heavy metals contaminated soil and can be employed in the treatment of such contaminated environment.Item MOLECULAR CHARACTERISATION OF SOME MULTI-DRUG RESISTANT SALMONELLA ENTERICA OF HUMAN ORIGIN IN SOUTHEAST NIGERIA(2016-01) ONYENWE, N. E.There has been an increase in the occurrence of antibiotic resistance among Salmonella enterica, one of the commonest causative agents of Salmonella infections. Fluoroquinolones and third generation cephalosporins are usually the drugs of choice in the management of Salmonella infections. Previous reports have indicated common occurrence of multi-drug resistance (MDR) including resistance to β-lactams and fluoroquinolones among clinical Gram-negative organisms. However, there is paucity of information on the genetic determinants of resistance to β-lactam and fluoroquinolones from S. enterica in Southeast Nigeria. This study screened for the presence of Extended-Spectrum Beta-Lactamases (ESBL) and mutations in gyrA and parC genes of S. enterica from human origin in the Southeast Nigeria. Twenty-five S. enterica isolates from stool of patients suspected to have Salmonella infection were collected from each of four hospitals (one teaching hospital and three Federal Medical Centres) in Southeast Nigeria between July and September, 2010. The isolates were confirmed using Microbact identification kit®. Antibiogram for the isolates was determined by disc-diffusion based on Clinical and Laboratory Standards Institute breakpoints. Five commonly used antibiotics (amoxicillin-clavulanic acid, cefotaxime, ceftriaxone, ciprofloxacin and levofloxacin) in the treatment of Salmonella infections were selected for determination of Minimum Inhibitory Concentrations (MIC) against the isolates using broth-dilution method. Isolates resistant to two or more different classes of antibiotics were classified as MDR. Isolates resistant to fluoroquinolones and cephalosporins were exposed to mutagens for R-plasmid curing, and ESBL were detected phenotypically using Double-Disk Synergy Test. Genomic and plasmid DNA of mutagen treated and untreated isolates were extracted by boiling and alkaline lysis, respectively. Polymerase chain reaction was used to amplify blaTEM, blaSHV and blaCTX-M among the ESBL positive isolates, and Quinolone Resistance Determining Regions (QRDR) among fluoroquinolone resistant isolates, followed by sequencing of the QRDRs. Antibiogram data were analysed using ANOVA at p = 0.05. The 100 clinical isolates collected were confirmed to be S. enterica. Percentage resistance obtained was: amoxicillin-clavulanic acid (87%), chloramphenicol (80%), amoxicillin (80%), co-trimoxazole (78%), sparfloxacin (78%), streptomycin (77%), gentamicin (51%), ceftazidime (44%), perfloxacin (29%), ciprofloxacin (29%), ofloxacin (28%), cefotaxime (27%), ceftriaxone (22%) and levofloxacin (22%). Eighty of the 100 isolates were MDR and the ranges of MICs of the selected antibiotics were: amoxicillin-clavulanic acid (≥ 50 µg/mL), cefotaxime (6.25 - 25 µg/mL), ceftriaxone (6.25 – 12.5 µg/mL), ciprofloxacin (6.25 – 12.5 µg/mL) and levofloxacin (12.5 - 25 µg/mL). Of the 100 isolates, nine MDR isolates carrying R-plasmid were cured. Thirty six of the MDR isolates produced ESBL phenotypically, of which 13 were blaCTX-M positive. DNA sequencing revealed single point mutations in gyrA at amino acid positions Asp-87-Gly, Asp-87-Asn and Ser-83-Tyr in 55 (68.8%), and double mutation in parC at positions Asp-87-Gly in 14 (17.5%). There was significant difference in the activity of the individual antibiotics against the isolates. The occurrence of mutations in gyrA and parC genes, and chromosomal blaCTX-M were responsible for fluoroquinolones and cephalosporins resistance, respectively in some of the Salmonella enterica from Southeast Nigeria. Hence, alleviating the fear of easy spreading of quinolone and cephalosporin resistant isolates.