Microbiology

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Antibiotic resistance patterns of bacterial isolates obtained from catfish and tilapia fish types consumed in Ibadan.
(Valahia University Press, 2018) Afolabi, F. T.; Fabunmi, F. K.
This study was carried out to identify antibiotic resistant bacteria isolated from Catfish (Clarias gariepinus) and Tilapia (Oreochromis sp.) fish types at Eleyele, University of Ibadan fish farm and Asejire all within Ibadan metropolis. Antibiotic susceptibility testing was carried out on Ninety (90) of the previously isolated bacterial isolates using the agar gel diffusion technique. Antibiotics used were Gentamycin, Ofloxacin, Nitrofurantoin, Ampicillin, Augmentin, Amoxicillin, Ceftazidime, Cefuroxime, Ciprofloxacin, Ceftriaxone, Erythromycin, Amikacin and Ticarcillin. Various level of multi drug resistance was observed among the isolates. The bacterial population identified from this study includes; Staphylococcus aureus, Salmonella sp., Shigella sp., Pseudomonas aeruginosa, Klebsiella pneumonia, Klebsiella oxytoca, Klebsiella ozaenae, Acinetobacter baumanii, Proteus vulgaris, Escherichia coli, Enterobacter aerogenes, Citrobacter freundii and Moraxella catarrhalis. Twelve (12) of the isolates were further subjected to plasmid profile analysis in which, plasmids of different sizes were found for 10 of the isolates. It was observed that only one Shigella sp., out of the Five (5) isolates had lost the plasmids and became responsible to the earlier resistant antibiotics while the other four isolates Klebsiella pneumoniae, Moraxella catarrhalis, Staphylococcus aureus maintained their resistance to the antibiotics. The spread of multidrug resistance pathogens has constituted a major impediment to the control of infectious diseases, and since this study has shown that fish samples could be a reservoir of bacteria carrying R-plasmids as well as genes responsible for resistance, therefore, the indiscriminate use of antibiotics should be discouraged and also national regulations on the use of antibacterial should be introduced and enforced.
ANTIMICROBIAL AND ANTI – INFLAMMATORY ACTIVITIES OF EXTRACTS OF FICUS THONNINGII BLUME (MORACEAE)
(2014-05) COKER, M. E.
Infectious diseases and the associated inflammation pose a serious health problem worldwide, accounting for about 50% of all deaths in tropical countries. This is further complicated by the frequent development of bacterial resistance to many chemotherapeutic agents. These problems have necessitated the continuous search for new and effective drugs from plant materials. Thus, Ficus thonningii Blume (Moraceae), a plant used ethnomedicinally in West Africa for the treatment of some microbial infections, was studied for its antimicrobial and anti-inflammatory activities. Dried leaves and stem bark of Ficus thonningii were screened for secondary metabolites. Successive gradient extraction was carried out on the pulverised plant parts using hexane, chloroform and methanol with Soxhlet apparatus. Antimicrobial activity of the extracts on Gram-positive (10) and Gram-negative (11) bacteria, and fungal (12) isolates was evaluated using agar-diffusion method. Antibiogram of the microorganisms was determined using established antibiotics. Bioassay-guided fractionation of crude extracts using column chromatography was done. Minimum Inhibitory Concentrations (MIC) and minimum bactericidal concentrations of the crude extracts, fractions and isolated compound were determined by agar-dilution. Bactericidal kinetics of the methanol leaf extract against Staphylococcus aureus and Escherichia coli at 2.5-10.0 mg/mL were determined. Structure elucidation of the bioactive compound was carried out using 1H-NMR, 13C-NMR, DEPT 135, COSY, UV and GC-MS spectroscopy. In vivo anti-inflammatory activity of leaf extract was evaluated using carrageenan-induced rat paw oedema with acetylsalicylic acid as the reference drug. Acute oral toxicity, haematological and histopathological evaluations were carried out to determine the safety profile of methanol leaf extract in rats. Statistical analysis was carried out using Student’s t-test at p = 0.05. Alkaloids, flavonoids, terpenoids and cardiac glycosides were detected in the plant extracts. Antimicrobial assay of crude extracts and fractions showed a broad spectrum activity on sensitive and multidrug-resistant strains with the leaf and stem bark extracts having similar antimicrobial activity. Hexane leaf extract and bioactive fractions gave MIC range of 78-625 µg/mL and 20-625 µg/mL respectively while methanol leaf extract and bioactive fractions gave 156-625 µg/mL and 39-625 µg/mL. Structure elucidation of the bioactive compound isolated from hexane leaf fraction revealed a triterpenoid with MIC range of 20-156 µg/mL (Gram-positive bacteria), 39-156 µg/mL (Gram-negative bacteria) and 10-78 µg/mL (fungi), while that of gentamicin and tioconazole were 5-30 µg/mL and 10-20 µg/mL respectively. Methanol leaf extract showed bactericidal activity in a concentration-dependent manner on the microorganisms, with a 100% bactericidal action at 10 mg/mL on Staphylococcus aureus and 84% on Escherichia coli within 4 hours. The anti-inflammatory activity of methanol leaf extract was 57.5% while that of acetylsalicylic acid was 93.2%. Acute oral toxicity of methanol leaf extract showed an LD50> 5g/Kg. Significant increases were observed in the red blood cell count and mean corpuscular haemoglobin value, while histopathological evaluation revealed no significant tissue pathological changes in the major organs. Extracts of Ficus thonningii leaves contain antimicrobial and anti-inflammatory agents. These could be useful in the development of safe chemotherapeutic agents for the treatment of relevant microbial infections and inflammation-prone diseases.
Bacteriological quality of some Nigerian currencies in circulation
(Academic Journals, 2010) Awe, S.; Eniola, K. I. T.; Ojo, F. T.; Sani, A.
The bacteriological quality of some Nigerian currencies in circulation was investigated in terms of total bacterial count and kinds of bacterial species present. The notes had high bacterial counts: ranging from 1.5×104 to 4.2×104 cfu/cm2; there was no significant difference in the bacterial counts. Eight bacterial species were isolated: Escherichia coli, Staphylococcus aureus, Proteus mirabilis, Streptococcus faecalis, Klebsiella sp., Pseudomonas aeroginosa, Bacillus subtilis and Salmonella sp. Salmonella sp. was the least prevalent of the bacterial isolates (2%) while S. aureus was the most prevalent (28%). Antibiotic susceptibility pattern suggests that some of the isolates (S. aureus and P. mirabilis) had potentials for multiple antibiotic resistances. The health implications of the organisms encountered are discussed and suggestions are provided to enable safe handling of the notes.
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.
Bioethanol production from decaying oranges and pineapple juice using ethanol tolerant-yeast
(Sciencedomain International, 2023) Omoolorun, J. B.; Afolabi, F. T.; Olufemi, S. E.; Adeyemo, S. M.
Scientists across the globe ought to harness ways of getting alternative sources of energy which will be renewable, sustainable, efficient, eco-friendly, and cost effective because of the global energy crises owing to the cost of production, transportation and distribution of fossil fuel products. In Nigeria, decaying fruits always constitute a major environmental pollution during the harvesting season. This study screened, selected the best starter, and produced bioethanol from the juice obtained from decaying oranges and pineapple through the process of fermentation and distillation. Samples were collected from different locations within Ile-Ife and transported aseptically to the Laboratory. Microbiological and physicochemical assessment of the isolated strains were on yeast maintenance media. The cell biomass, pH, temperature, brix level, titratable acidity, specific gravity and ethanol yield were monitored during fermentation from day zero to day fourteen. Screening of the isolates obtained from a previous study was carried out to select the best starter for the production of bioethanol. S.cerevisae and K. marxianus and showed efficient physico-chemical attributes from the screening of the yeast isolates; a temperature of 30oC and pH 6 was the optimum for the growth of isolates tolerating 20% v/v absolute ethanol. Cultures were inoculated singly and in combination, S. cerevisiae gave the highest reduction in brix level from 2.2o at the onset and it reduced to 0.3o at the 21st day of fermentation while the least reduction was seen in K. marxianus. Mixed culture of S. cerevisiae and K. marxianus gave the highest reduction in brix level from 2.0o at the onset to 0.1o, pH reduced from 4.7- 3.3 while the cell biomass increased, and the temperature increased from 30oC to 34.5oC at the end of fermentation. Titratable acidity in the fermenting fruits juice increased from 0.23 to 1.76, the specific gravity reduced while the alcohol content increased from zero to 25.63 as the fermentation progressed and a reduction on day 21 (1.67) was observed. The use of decaying plant biomass or fruit waste can be a rich and cheaper source of substrate for different yeasts strains endogenous to the biomass for the production of environmental-friendly biofuel. This can also be employed as a waste management option and an alternative solution to environmental pollution and the global energy crises.
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.
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.
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.
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."
Characterization and screening of lactic acid bacteria (LAB) and yeast from fermented sorghum and maize products for use as starter culture.
(Science domain International, 2021) Ayodeji, O. C.; Afolabi, F. T.; Abdulkadir M.
This study focused on the isolation, Characterization and screening of lactic acid bacteria and yeast for use as starter culture in order to eradicate the problem of excessive microbial contamination and the presence of mycotoxins. Lactobacillus plantarum and Saccharomyces cerevisiae were the predominant microorganisms isolated from the samples collected. The isolates were screened for their ability to produce enzymes and metabolites. Lactic acid bacteria produce a variety of antimicrobial compounds such as lactic acid, hydrogen peroxide, diacetyl on them as a natural competitive means to overcome other microorganism sharing the same niche. They were also screened for their ability to withstand some physiological stress like acid tolerance, temperature, salt concentration and antibacterial activity; the isolates produced significant values of enzymes and, antimicrobial metabolites. The antimicrobial activity of Lactobacillus plantarum is mainly attributed to the low pH due to Lactic acid production. The antimicrobial activity of the Saccharomyces cerevisiae appears to be mainly due to the competition with the other microorganisms. In addition, depletion of Oxygen and production of CO2, competition for nutrients and the production of antimicrobial substances could have been responsible for the overall antimicrobial activity of both cultures. According to the results obtained, both lactic acid bacteria and yeast proved to be a good source of starter culture.
Characterization of lipase produced by lipolytic yeast isolated from different lipidic samples
(The Nigerian Society for Microbiology & Microbiology Department, Kaduna State University, Nigeria, 2024) Afolabi, F. T.; Abass A. I.; Ayodele, E. O.; Oduokpaha, G. E.
Lipases are considered as nature's potential catalysts that hydrolyze triglycerides into diglycerides, monoglycerides, fatty acids and glycerol. Lipases also catalyze wide range of different reactions. Yeasts are among the microorganisms in addition to bacteria and fungi, which are capable of producing lipases. The aim of this research was to characterise lipase produced by lipolytic yeast isolated from different lipidic samples. A total of thirty-six (36) yeast isolates were obtained from different [pidic samples which include: palm kernel cake, palm kernel shell, palm kernel fibre, beef, fish, rice, cheese and whey. Twenty (20) of the yeast isolates showed lipolytic activities based on the qualitative screening for lipase production. Pichia kluvyerii PCF a and Candida parapsilosis FBBa were the best ipolytic yeast isolates. P. kluvyerii PCFa showed optimal activity (4.71U/mL) at 35°C, and C. parapsilosis FBBa showed optimal activity (2.82U/mL) at 25°C. Both yeasts exhibited high activity at 50°C and pH 7.5, and were therefore identified as thermostable, sightly alkali-tolerant lipases. P. kluvyeri PCFa lipase exhibited optimal activity at pH 7.0, while C parapsilosis FBBa lipase exhibited optimal activity at pH 7.5. Optimal activity was demonstrated by the two lipases after 5min of the reaction time, when 1.0% olive oil was used as substrate, and in presence of n-Hexane organic solvent. This study showed that the samples used are good sources for the isolation of lipolytic yeast and the lipases are promising industrial enzymes.
CHARACTERIZATION OF β-GALACTOSIDASE BY LACTIC ACID BACTERIA FROM MILK AND TRADITIONALLY FERMENTED MILK PRODUCTS FROM IBADAN
(2014-01) PARKHA, O. A.
Lactose intolerance (a condition in which man elucidates an immune reaction towards the presence of lactose due to inability to produce enzyme lactase) is a major nutritional deficiency among some adult consumers of milk and other dairy products worldwide. β–galactosidase hydrolysis of milk is one of the promising enzymatic applications in dairy industries for reducing lactose intolerance of milk products. However, plant and animal sources cannot meet the high demand of the enzyme in food industries. Hence, the aim of this study was to characterize β–galactosidase production by Lactic Acid Bacteria (LAB) isolated from locally fermented milk products. Raw milk from Sokoto Gudali was collected from Fulani settlement in Ojoo, Ibadan along with some fermented milk products (‘’Nono’’ and ‘’Wara’’). LABs were isolated from them and identified using conventional methods. The ability of the isolates to hydrolyze 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal) was used to screen for β–galactosidase production. Isolates with the best β-galactosidase production were selected. The enzyme was extracted and optimization of growth conditions (temperature, pH, nitrogen, carbon sources, inoculums size and inoculums age) for β-galactosidase production was carried out using o-nitrophenyl-β-D-galactopyranoside (ONPG). The enzyme produced was characterized using pH, temperature, metal and non-metal ions, and inhibitors. Purification of the enzyme was carried out using dialysis and chromatographic methods. Hydrolytic effects of the purified β–galactosidase were determined in different concentrations of lactose using standard method. Data were analyzed using descriptive statistics. The isolated bacteria were identified as Lactobacillus plantarum (G11, E13 and E36), L. brevis, L. casei, L. lactis, Leuconostoc lactis, Streptococcus sp, and Bacillus subtilis. Lactobacillus plantarum (G11) had optimum growth value of 4.2 at 20°C and pH 7.0 with maximum enzyme value of 6.2U/mL at 30 hrs. The optimal β-galactosidase production occurred at neutral pH and 6% inoculum size. The best inoculums age varied between 18 hrs and 36 hrs. The best carbon source for enzyme production was raffinose with maximum value of 0.3U/mL while minimum activity was found in fructose with 0.2U/mL. The best nitrogen source was NH4NO3 with maximum value of 0.5U/mL and yeast extract had minimum value of 0.1U/mL. β–galactosidase activity increased with increase in molar concentration of the mono-valent chloride ions in which the highest was recorded in KCl at maximum value of 0.08U/mL while the minimum value of 0.001U/mL was obtained by NaCl at a concentration of 0.2 mmol respectively. The best sulfate ion was CuSO4 with maximum activity value of 0.2 U/mL at 0.2 mmol concentration and minimum value of 0.007 U/mL at 0.1 mmol by ZnSO4. The best enzyme inhibitor was KCN with maximum activity of 0.2U/mL at 0.2 mmol. The specific activity of β-galactosidase was 292.5 U/mg, 104.2 U/mg and 585.46 U/mg for G11, E13 and E36 respectively. The hydrolytic effects of the purified β-galactosidase showed a maximum yield of 35.8% glucose, 19.3% galactose and 35.3% glucose and 18.5% galactose at 80% and 60% lactose concentration respectively. β-galactosidase produced by Lactobacillus plantarum strain achieved lactose hydrolysis and could be of potential application for production of low lactose dairy products for consumption by lactose intolerant people.
Comparative study of bioethanol production and reducing sugar yields from cassava peels using fungi
(Bulgarian Society for Microbilogist, 2020) Afolabi, F. T.; Ayodele E. O.
This study compared the yields of bioethanol from the fermentation of pretreated cassava peels using yeasts isolated from palm wine, and a pretreatment method with methanol + acid before solid-state fermentation of cassava peels using Trichoderma reesei for 5 days optimally yielded 1.78 g/mL of reducing sugar. The hydrolysate was fermented for bioethanol production using Saccharomyces cerevisiae and Candida tropicalis. S. cerevisiae performed optimally at 30oC, pH 4.5, and produced ethanol with a concentration of about 40.72 g/L, while C. tropicalis produced 29.90 g/L of ethanol concentration at 35oC, and pH 5. Both yeast isolates took the same fermentation time of 96 h. In conclusion, cassava peels are agricultural waste that is a degradable material suitable to produce simple reducing sugars, which can be fermented by yeast to produce bioethanol. The yield of ethanol was higher for S. cerevisiae than C. tropicalis.
DEGRADATION OF POLYAMIDE-6 BY MICROBIAL ISOLATES FROM SOLID WASTE DUMPSITES IN LAGOS STATE, NIGERIA
(2012-10) SANUTH, H. A.
Polyamide-6 (also known as nylon-6) is one of the biodegradation-resistant synthetic polymers used in the manufacturing of commodity plastic materials. The environmental effects of the persistence of this material in landfill and on surface water bodies pose global problems that endanger public health. Knowledge of the microbial distribution and pattern of their interaction with these plastics will provide the biological resources and scientific basis for the development of sustainable disposal and treatment method. Therefore, microbial degradation of polyamide-6 and its monomers were investigated. Soil samples were randomly collected at five spots to a depth of 15cm and mixed to form composites from each of the three selected dumpsites at Olusosun, Abule-Egba and Isheri-Igando in Lagos state. Microbiological analysis was carried out on the samples on bimonthly intervals over a period of eight months. The fungal and bacterial isolates were screened for their ability to utilize ε-caprolactam (the monomer of the nylon-6) as a sole source of carbon and nitrogen for growth on a synthetic solid medium and were phenotypically characterized. The 16SrRNA gene sequences were used for the molecular typing of the isolates. The isolates with the best growth within 120hrs in ε-caprolactam medium were tested for nylon-6 degradation. Intermediate products in the culture medium were monitored using High Performance Liquid Chromatography (HPLC) while biodegradation of the nylon-6 was monitored using Fourier Transform Infrared Spectroscopy (FTIR), average number molecular mass (Mn) and weight loss. An un-inoculated experiment served as the control. Data obtained were analysed using ANOVA. A total of 64 bacteria and 22 fungi were isolated from the soil samples. Sixteen species of the bacterial isolates made up of the genera Pseudomonas (5), Alcaligenes (3), Corynebacterium (2), Leucobacter (2), Bordetella (1), Proteus (1), Providencia (1) and Lysinibacillus (1) were capable of utilising ε-caprolactam as the sole source of carbon and nitrogen up to a minimum inhibitory concentration of 20 gL-1. The fungi were identified as five species of Aspergillus and a species of Penicillium. Proteus vulgaris utilized 97.2%, Bordetella petrii 92.5%, Pseudomonas aeruginosa (NTS1) 90.5% and Alcaligenes faecalis (2ABA2) 82.3% of 10 gL-1 ε-caprolactam within 120hrs compared to the control experiment. The HPLC analysis of the culture supernatant revealedthe presence of 6-aminohexanoic acid, ε-caprolactam and some un-identified oligomers as the degradation products of the nylon-6 fibre. The changes observed in the FTIR spectra of different functional groups confirmed the effect of microbial degradation of the nylon-6 fibre. Aspergillus niger was the most efficient of the fungi isolates in degrading the polyamide-6. It achieved 29.77 % reduction in polyamide-6 Mn and 23.95 % weight loss. Moreover, P. aeruginosa (NTS1) degraded Polyamide-6 with 12.82 % reduction in Mn and 5.23% weight loss. These changes were found to be significant at p = 0.05. Aspergillus niger and Pseudomonas aeruginosa degraded nylon-6 fibre and this serves as baseline information for the bio-treatment of the nylon polymer.
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.
ENVIRONMENTAL HYGIENE AND MICROBIOLOGICAL ASSESSMENT OF FOOD SERVICE ESTABLISHMENTS IN SELECTED BOARDING HIGH SCHOOLS IN IBADAN, NIGERIA
(2023-07) ADEBAYO, K.A
Schools’ Food Service Establishments (FSEs) have been incriminated in numerous foodborne diseases outbreaks globally and have been linked to the environment and food handling procedures in the establishments. Despite this, FSEs in Nigerian boarding schools have been poorly investigated. In order to provide baseline data for infection control, this study was designed to assess environmental hygiene and food handlers’ Knowledge, Attitude and Practices (KAP) and investigate food-related microbial contamination from selected boarding schools’ FSEs in Ibadan, Nigeria.Observational checklist and interviewer-administered questionnaire were used to evaluate environmental hygiene parameters, food handlers’ KAP in four schools’ FSEs out of forty-three schools by inclusion criteria and balloting. Swabs from Food Contact Surfaces (FCS): utensils and surfaces; 20 food handlers’ hands and samples of Ready to-Eat (RTE) foods were examined for Aerobic Plate Count (APC), Total Coliform (TC), Faecal Coliform (FC) and selected important foodborne pathogens counts using standard methods. Isolated bacteria were characterised phenotypically and subjected to 16S rRNA sequencing. Antibiotic susceptibility testing was determined using disc diffusion and E-strip techniques based on CLSI and EUCAST standards, respectively. Data were analysed using descriptive statistics and ANOVA at α0.05. Schools FSEs’ compliance mean scores for environmental hygiene parameters were 82.2, 56.8, 52.7 and 65.6% for toilets, dining areas, kitchens and observed food handlers at work, respectively. The food handlers had good knowledge (61.9%), positive attitude (81.4%) to ensure food safety, but poor hygiene practices (52.6%) which differed significantly among schools (p=0.012, χ2=10.15). Major unsanitary practices observed were: use of basins and buckets for dish washing, uncovered solid waste receptacles, non-availability of sanitising agents and inadequate handwashing. Mean logCFU/cm2 of APC for counter tops, chopping boards, grinders, trays and knives were 5.59±1.56, 4.38±2.62, 4.01±0.77, 2.47±2.23 and 2.38±1.75, respectively. Food handlers’ hands’ mean logCFU/cm2 of APC, TC, FC, Staphylococcus and Bacillus species were 3.10±1.78, 2.62±1.23, 2.80±1.74, 1.94±1.04 and 1.97±1.39, respectively. Seventy-eight percent of RTE foods conformed to acceptable limit of < 4logCFU/g for APC. The distribution of bacteria from schools FSEs were 62.0% (FCS), 19.0% (food handlers’ hands) and 19.0% (RTE foods). The identified food-related bacteria were Alcaligenes faecalis, Achromobacter xylosoxidans, Bacillus cereus, Ochrobactrum anthropi,viiiProteus mirabilis, Serratia marcescens, Staphylococcus saprophyticus and Bordetella species. Alcaligenes faecalis resistance (%) to cefixime, cefuroxime, ceftazidime, gentamicin, augmentin, nitrofurantoin, ofloxacin and ciprofloxacin were 76.2, 71.4, 66.7, 61.9, 57.1, 42.9, 4.8 and 4.8, while for Bacillus cereus, they were 85.7,100.0, 57.1, 85.7, 28.6, 57.1, 0.0 and 0.0, respectively. The minimum inhibitory concentration of colistin for Alcaligenes faecalis ranged from 1.5 µg/mL to >256 µg/mL which was highly significant (F=9.194, p<0.05) compared to other antibiotics. Two Bacillus cereuswere resistant to imipenem, 81.0% were multi-antibiotic resistant, while none of the identified bacteria showed resistance to piperacillin/tazobactam.Food contact surfaces and food handlers’ hands were grossly contaminated. The presence of colistin-resistant Alcaligenes faecalis and resistance of Bacillus cereus to imipenem in boarding schools’ food service establishments is a serious public health concern. These findings will be useful in policy formulation and the development of food safety guidelines in boarding schools.
Environmental Impact Assessment Studies (EIA)
(Ajayi Crowther University,, 2009) Dada, S. S.; Awe, S.; Ojo, F. T.
Fermentation conditions and process optimization of citric acid production by yeasts
(Conscientia Beam, 2018) Afolabi, F. T.; Adeyemo, S. M.; Balogun, H. O.
The aim of this study was to isolate and screen citric acid producing yeasts using low cost substrates. Thirty three yeast isolates were obtained from pineapple, plantain and sugar cane waste and identified as; Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida tropicalis, Pichia guilliiermondii, Debaromyces sp., Candida parapsilosis, Candida rugosa, and Candida krusei. Candida tropicalis had zone of clearance of 49±2.1 mm in diameter, Pichia guilliermondii had 40±1.2mm. Saccharomyces cerevisiae produced citric acid with glucose with 105.0 mg/l. C. tropicalis yielded 132.2 mg/l with sodium nitrate. S. cerevisiae and C. tropicalis produced citric acid at pH 6 with 23.70mg/l and 23.80mg/l. P. gulliermondii at pH 4 produced 23.00mg/l. The temperature of 30°C favoured S. cerevisiae and C. tropicalis yielding 40.80mg/l and 39.80 mg/l. After extraction, the yield of the citric acid was 4.231g, 3g of which was recrystallized to yield 2.16g of pure citric acid resulting into 72% recovery. The result indicated that pineapple wastes, plantain wastes and sugarcane cane are potential sources of yeasts that can be used for the production of citric acid.
FERMENTATION OF COCOA (Theobroma cacao L.) POD HUSK AND ITS HYDROLYSATE FOR ETHANOL PRODUCTION USING IMPROVED STARTER CULTURES
(2012-07) IGBINADOLOR, R. O.
Fossil fuel, a main but dwindling energy source for automobiles, causes emission of environment unfriendly oxides of carbon. These contribute substantially to greenhouse gases which bring about climate change. There is therefore the need for sustainable source of energy like ethanol an environmental friendly bioenergy. Hence this study was aimed at the fermentation of cocoa pod husk for ethanol production. Isolates of yeast were obtained from sun-dried Cocoa Pod Husk (CPH), subjected to spontaneous submerged fermentation for 7 days. Five strains of Saccharomyces sp. (MX1, MX2, MX3, MX4 and MX5) with high frequency of occurrence were selected for further studies. The MX1 and MX2 were used for genetic modifications. Dried CPH was subjected to chemical analysis and pretreatment using particle size reduction and high pressure liquid hot water at 130oC for 30 minutes. Acid and enzymatic hydrolysis of the pretreated CPH was carried out using standard method. Products of the hydrolysis were analysed with high performance liquid chromatography. Two genes XL1 (xylose reductase) and XL2 (xylitol dehydrogenase) encoding pentose utilization were obtained from genomic DNA of Pichia stipitis (CBS 6054) using basic local alignment search tool. Primers of these genes were designed with Saccharomyces genome database, amplified with Polymerase Chain Reaction (PCR) and purified. The amplicon (genes) were ligated into plasmid vectors (pGAPZA and pVT100-U). Strains MX1 and MX2 were transformed with these construct using lithium acetate method. Physiological characterization of the selected unmodified yeast strains and the two genetically-modified strains was done under different environmental conditions including temperatures, pH and varied concentrations of acetic acid. The CPH hydrolysates were fermented for 120 hours using the unmodified and genetically-modified yeast strains respectively and the ethanol yield determined. Data were analysed using ANOVA. Twenty yeast isolates identified as Saccharomyces cerevisiae (80%) and Saccharomyces uvarum (20%) were obtained. Chemical composition of CPH included hemicellulose (13.9%) cellulose (18.6%) and lignin content (14.2%). Acid hydrolysis yielded 50.1% glucose, 11.97% xylose, 11.2% mannose while enzymatic hydrolysis gave 31.7% glucose, 4.8% mannose and 16.8% galactose. The inserted gene XL1 had 318 amino acids polypeptides while XL2 had 363 amino acid polypeptides. Restriction enzyme analysis and colony PCR confirmed the transformational integration of these constructs into Saccharomyces cerevisiae MX1 and MX2. The five isolates had optimal growth at 30 – 40oC and pH of 4.0 – 5.5. However the genetically-modified yeast strains were able to utilize xylose and arabinose carbon sources better than the unmodified types and also tolerated low concentration of acetic acid than the unmodified types. Ethanol production was highly significant (p0.05) in the modified starters (29.7g/L) than the unmodified strains (14.0g/L). Genetically-modified organisms performed better in ethanol production than the non-modified organisms. The application of genetic modification of microorganisms will aid the potential use of waste biomass like cocoa pod husk for bioenergy production and this will contribute significantly to reducing greenhouse gases associated with climate change.
Fungi associated with fermented cocoa beans during sun-drying in a farm settlement in Edo State, Nigeria
(Globeedu Group, 2017) Igbinadolor, R. O.; Afolabi, F. T.; Okunade, A. F.
Fungi associated with cocoa beans during sun drying were carried out for eight days in a village in Edo State of Nigeria during the month of September, 2016. Raised platform of local mat constructed with bamboo was used for the sun-drying. Eight fungi were encountered at different time interval from the drying cocoa bean and identified as A. niger, Penicillium sp. A. flavus, Rhizopus sp., Phytophthora sp., Fusarium sp, A. fumigatus and Botryodiploda sp, respectively. The frequency of occurrences of the different fungal isolates in the work showed that A. niger (27.8%) and Penicillium sp (20.4%) had the highest frequency of occurrence during the period of sun drying. This was followed by A. flavus (16.7%), Rhizopus sp (11.1%), Phytophthora sp. (7.4%), Fusarium sp (7,4%), A. fumigatus (5.6%) while Botryodiploda sp had the lowest frequency of occurrence (3.7%).Observation of good agricultural and sun-drying practices is therefore necessary to reduce the mould population on the beans and thus limit the risk of contamination.