Microbiology
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Item Isolation and screening of phytase-producing fungi for phytase production by solid state fermentation using agro wastes(Plovdiv University Press, 2025) Afolabi, F. T.; Atunwa S. O.Phytases are phosphatase enzymes that catalyze the hydrolysis of phytic acid and its salts. This study aimed to isolate and screen for phytase-producing fungi from cereals, fruits, palm kernel cake and soil samples by solid state fermentation. Isolation and identification was done using standard methods. The fungal isolates were screened for phytase production using phytase screening medium (PSM) agar. The isolates with the highest and consistent zone of hydrolysis were used. Eighty seven (87) fungal isolates were obtained while eighteen showed consistent zone of hydrolysis. These were screened to five (5) isolates: Aspergillus niger PKruw7, Aspergillus awamori Pkruw5, Aspergillus flavus PBDJ7, Aspergillus niger MOJ5b and Penicillium chrysogenum OBDJ1.They were used for solid state fermentation using rice bran, soy bean and wheat bran for phytase production. The optimized conditions for phytase production were: 40ºC temperature, 5.5 pH, 1% w/w fructose and 0.5% w/w yeast extract by both Aspergillus niger PKruw7 and Aspergillus flavus PBDJ7, 40ºC, 4.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus awamori Pkruw5, 25ºC, 6.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus niger MOJ5b and 40ºC, 4.5 pH, 1% w/w sucrose and 0.5% w/w (NH4) 2SO4: Penicillium chrysogenum OBDJ1with incubation period of 120 hours optimal for all the isolates. Maximum phytase production from optimized culture conditions include; incubation period of 5 days, temperature of 40°C, pH of 4.5 to 6.5, fructose (1% w/w), yeast extract and ammonium nitrate (0.5% w/w). Phytase can be applied in animal feed to enhance digestibility and nutrient availability.Item 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.Item Screening of yeasts obtained from different fermented foods for their ability to produce pectinase(Joanna Bródka, Poland, 2020) Afolabi, F. T.; Shitta Y. O.In the present study, Citrus pectin was used for the production of pectinase enzyme by yeast isolates using submerged fermentation. Fifty yeasts were isolated from different fermented foods and screened for their producing ability. Candida sp. OG2 and Candida tropicalis strain AUMC 10275 were the yeast isolates with the best potential of pectinase production. Fermentation parameters such as incubation period, pH, temperature, carbon and nitrogen source were optimized under submerged fermentation. The optimal conditions for pectinase production were found to be incubation time 48 hours, pH 6.0 and temperature 40°C. Citrus pectin best induced the production of pectinase while yeast extract/peptone (1:1) was the best source of nitrogen. Pectinase produced by Candida tropicalis strain AUMC 10275 was purified at 4.00 folds with a specific activity of 63.99 U/ml. The yeasts obtained from fermented foods have the ability to produce pectinase enzyme under optimized conditions and can be used for industrial purposes.Item Isolation and characterization of ethanol-tolerant yeasts from decaying oranges for the production of bioethanol(Institute of Ecology and Environmental Studies, Faculty of Science, Obafemi Awolowo University (OAU), Ile-Ife, Osun State, Nigeria., 2017) Adeyemo, S. M.; Afolabi, F. T.; Awojobi, K. O.; Ojo, O. O.Decaying orange fruits are readily available agricultural waste in Nigeria, yet they seem to be underutilized as potential growth medium for local yeasts strains, despite their rich carbohydrate content that can support yeast growth. The ability of different strains of yeasts to grow on orange biomass and its utilization as raw material for the production of bio-ethanol was investigated in this study. Five replicate samples of decaying oranges were collected at different time intervals from dump sites at five different local markets in Ile-Ife from which different species of yeasts were isolated. Standard biochemical tests were conducted to identify and confirm their identities. Fermentation of orange juice was done with the yeast strains singly and in combination at 30°C for seven days and parameters essential for ethanol production such as titratable acidity, pH, specific gravity, Brix and Ethanol tolerance and content were determined following Association of Official Analytical Chemist procedures. Data were analysed using ANOVA at p=0.05. A total of thirty yeast isolates were isolated and identified as Saccharomyces cerevisiae, Schizosaccharomyces japanicus, Candida valida, Candida fructus, Candida krusei, Kluyveromyces africanus and Rhodotorula gramis. Abundant production of bioethanol was derived from S. cerevisiae, C. fructus and C. valida (C. fructus and C. valida were used singly while C. fructus and Saccharomyces were combined in the ratio 1:1). The highest alcohol value (7.65%) was derived from the mixed strain (Candida fructus and Saccharomyces cerevisiae) and the lowest value of alcohol (6.98%) from a single culture of Candida fructus. Decaying oranges, its juice and its biomass could be used to produce bio-ethanol which is of a good quality. The method is effective and efficient with high yield eco-friendly ethanol. The fruit waste which provides readily available and cheap substrates for industrial use and at the same time solves the problem of environmental pollution that the decaying oranges cause if not disposed appropriately.Item Isolation and screening of phytase-producing fungi for phytase production by solid state fermentation using agro wastes(Plovdiv University Press, 2025) Afolabi, F. T.; Atunwa S. O.Phytases are phosphatase enzymes that catalyze the hydrolysis of phytic acid and its salts. This study aimed to isolate and screen for phytase-producing fungi from cereals, fruits, palm kernel cake and soil samples by solid state fermentation. Isolation and identification was done using standard methods. The fungal isolates were screened for phytase production using phytase screening medium (PSM) agar. The isolates with the highest and consistent zone of hydrolysis were used. Eighty seven (87) fungal isolates were obtained while eighteen showed consistent zone of hydrolysis. These were screened to five (5) isolates: Aspergillus niger PKruw7, Aspergillus awamori Pkruw5, Aspergillus flavus PBDJ7, Aspergillus niger MOJ5b and Penicillium chrysogenum OBDJ1.They were used for solid state fermentation using rice bran, soy bean and wheat bran for phytase production. The optimized conditions for phytase production were: 40ºC temperature, 5.5 pH, 1% w/w fructose and 0.5% w/w yeast extract by both Aspergillus niger PKruw7 and Aspergillus flavus PBDJ7, 40ºC, 4.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus awamori Pkruw5, 25ºC, 6.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus niger MOJ5b and 40ºC, 4.5 pH, 1% w/w sucrose and 0.5% w/w (NH4) 2SO4: Penicillium chrysogenum OBDJ1with incubation period of 120 hours optimal for all the isolates. Maximum phytase production from optimized culture conditions include; incubation period of 5 days, temperature of 40°C, pH of 4.5 to 6.5, fructose (1% w/w), yeast extract and ammonium nitrate (0.5% w/w). Phytase can be applied in animal feed to enhance digestibility and nutrient availability.Item Isolation and screening of phytate-degrading yeasts from cereals(Federal University Dutsin-Ma, 2025) Afolabi, F. T.; Gyegweh K. T.Application of phytase (myo-inositol hexakisphosphate phosphohydrolase) to catalyze the release of phosphate from phytates contained on grain-based feed has been used widely. This study was carried out to isolate, identify, screen and produce yeast phytase from cereals using submerged fermentation. Two hundred and twenty seven (227) yeast isolates were obtained from maize, sorghum and millet and identified based on various characteristics such as colony morphology, microscopy, biochemical tests, sugar fermentation tests and molecular analysis. The isolates were then screened for phytase production by growing them on Phytase Screening Medium (PSM) and observing the formation of a clear zone around their colonies, indicating their ability to degrade phytate. It was found that yeast species such as Pichia membranefaciens, Meyerozyma guilliermondii SWS81, Candida krusei, M. guilliermondii M122, Pichia fermentans, M. guilliermondii WM226 and Schwanniomyces occidentalis, were capable of phytate degradation. M. guilliermondii M122, M. guilliermondii SWS81, and M. guilliermondii WM226 with higher solubilizing indices (4.52 mm, 3.64 mm and 5.14 mm respectively) were selected for production and assay. The results showed that crude enzymes from these yeast strains had phytase activity ranging from 44.70 U/mL to 97.70 U/mL, making them potential supplements for animal feeds to improve nutritional status and combat environmental phosphorus pollution.Item Isolation and screening of phytate-degrading yeasts from cereals(Federal University Dutsin-Ma, 2025) Afolabi, F. T.; Gyegweh K. T.Application of phytase (myo-inositol hexakisphosphate phosphohydrolase) to catalyze the release of phosphate from phytates contained on grain-based feed has been used widely. This study was carried out to isolate, identify, screen and produce yeast phytase from cereals using submerged fermentation. Two hundred and twenty seven (227) yeast isolates were obtained from maize, sorghum and millet and identified based on various characteristics such as colony morphology, microscopy, biochemical tests, sugar fermentation tests and molecular analysis. The isolates were then screened for phytase production by growing them on Phytase Screening Medium (PSM) and observing the formation of a clear zone around their colonies, indicating their ability to degrade phytate. It was found that yeast species such as Pichia membranefaciens, Meyerozyma guilliermondii SWS81, Candida krusei, M. guilliermondii M122, Pichia fermentans, M. guilliermondii WM226 and Schwanniomyces occidentalis, were capable of phytate degradation. M. guilliermondii M122, M. guilliermondii SWS81, and M. guilliermondii WM226 with higher solubilizing indices (4.52 mm, 3.64 mm and 5.14 mm respectively) were selected for production and assay. The results showed that crude enzymes from these yeast strains had phytase activity ranging from 44.70 U/mL to 97.70 U/mL, making them potential supplements for animal feeds to improve nutritional status and combat environmental phosphorus pollution.Item Isolation and screening of phytase-producing fungi for phytase production by solid state fermentation using agro wastes(Plovdiv University Press, 2025) Afolabi, F. T.; Atunwa S. O.Phytases are phosphatase enzymes that catalyze the hydrolysis of phytic acid and its salts. This study aimed to isolate and screen for phytase-producing fungi from cereals, fruits, palm kernel cake and soil samples by solid state fermentation. Isolation and identification was done using standard methods. The fungal isolates were screened for phytase production using phytase screening medium (PSM) agar. The isolates with the highest and consistent zone of hydrolysis were used. Eighty seven (87) fungal isolates were obtained while eighteen showed consistent zone of hydrolysis. These were screened to five (5) isolates: Aspergillus niger PKruw7, Aspergillus awamori Pkruw5, Aspergillus flavus PBDJ7, Aspergillus niger MOJ5b and Penicillium chrysogenum OBDJ1.They were used for solid state fermentation using rice bran, soy bean and wheat bran for phytase production. The optimized conditions for phytase production were: 40ºC temperature, 5.5 pH, 1% w/w fructose and 0.5% w/w yeast extract by both Aspergillus niger PKruw7 and Aspergillus flavus PBDJ7, 40ºC, 4.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus awamori Pkruw5, 25ºC, 6.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus niger MOJ5b and 40ºC, 4.5 pH, 1% w/w sucrose and 0.5% w/w (NH4) 2SO4: Penicillium chrysogenum OBDJ1with incubation period of 120 hours optimal for all the isolates. Maximum phytase production from optimized culture conditions include; incubation period of 5 days, temperature of 40°C, pH of 4.5 to 6.5, fructose (1% w/w), yeast extract and ammonium nitrate (0.5% w/w). Phytase can be applied in animal feed to enhance digestibility and nutrient availability.Item Isolation and screening of phytase-producing fungi for phytase production by solid state fermentation using agro wastes(Plovdiv University Press, 2025) Afolabi, F. T.; Atunwa S. O.Phytases are phosphatase enzymes that catalyze the hydrolysis of phytic acid and its salts. This study aimed to isolate and screen for phytase-producing fungi from cereals, fruits, palm kernel cake and soil samples by solid state fermentation. Isolation and identification was done using standard methods. The fungal isolates were screened for phytase production using phytase screening medium (PSM) agar. The isolates with the highest and consistent zone of hydrolysis were used. Eighty seven (87) fungal isolates were obtained while eighteen showed consistent zone of hydrolysis. These were screened to five (5) isolates: Aspergillus niger PKruw7, Aspergillus awamori Pkruw5, Aspergillus flavus PBDJ7, Aspergillus niger MOJ5b and Penicillium chrysogenum OBDJ1.They were used for solid state fermentation using rice bran, soy bean and wheat bran for phytase production. The optimized conditions for phytase production were: 40ºC temperature, 5.5 pH, 1% w/w fructose and 0.5% w/w yeast extract by both Aspergillus niger PKruw7 and Aspergillus flavus PBDJ7, 40ºC, 4.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus awamori Pkruw5, 25ºC, 6.5 pH, 1% w/w fructose and 0.5% w/w NH4NO3: Aspergillus niger MOJ5b and 40ºC, 4.5 pH, 1% w/w sucrose and 0.5% w/w (NH4) 2SO4: Penicillium chrysogenum OBDJ1with incubation period of 120 hours optimal for all the isolates. Maximum phytase production from optimized culture conditions include; incubation period of 5 days, temperature of 40°C, pH of 4.5 to 6.5, fructose (1% w/w), yeast extract and ammonium nitrate (0.5% w/w). Phytase can be applied in animal feed to enhance digestibility and nutrient availability.Item Utilization of Date palm (Phoenix dactylifera L.) wastes for bioethanol production using Pichia kudriavzevii strains(Researchers Links (United Kingdom), 2022) Afolabi, F. T.; Ola, I. E.Tons of Date palm (Phoenix dactylifera L.) fruit wastes are discarded daily by the date palm processing industries thus leading to serious environmental problems. This study aimed to investigate the potential of date palm fruit wastes as sugary feedstock for bioethanol production using yeasts. Proximate analysis of the date fruit wastes revealed a moisture content of 8.98 %; crude protein (4.39 %), ash (2.35 %), fat (0.2 %), fiber (0.8 %) and carbohydrate (84.28 %). Sulphuric acid was used for pre-treatment of the date palm fruit substrate. Fermentation was carried out under shaking and static conditions using Pichia kudriavzevii yeast strains isolated from date palm fruit wastes. Greater bioethanol yield was observed when the substrates were fermented under shaking condition. Optimization of the physical conditions improved the fermentation process faster, and significantly enhanced the production of bioethanol. An appropriate temperature of 30oC and pH 5 produced high yield of ethanol (5 %) by Pichia kudriavzevii SGD21, whereas pH 6 for Pichia kudriavzevii SGD30 recorded a higher ethanol yield of 6 %. Under the optimal physical conditions, the fermentation process resulted in the production of 4 % ethanol after an incubation period of 96 h. Moreover, the Pichia kudriavzevii strains could be recommended for bioethanol production at 30 % inoculum size, on using sucrose as a carbon source and yeast extract as a nitrogen source. On using the Fourier-Transform Infrared (FTI) spectroscopy, the detected functional group of the produced bioethanol was O-H group. Finally, utilization of date palm fruit wastes and the yeasts strains of Pichia kudriavzevii SGD21 and Pichia kudriavzevii SGD30 can be exploited for bioethanol production and this could be an effective way for management and utilization of date palm fruit wastes.