Microbiology

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Start date: 2020

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Now showing 1 - 10 of 26
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    Screening and characterisation of yeast species for citric acid production using glycerol and agro-waste
    (The Nigerian Society for Microbiology (NSM), 2025) Afolabi, F. T.; Adeoye, A. E.
    The present study was aimed to isolate and screen yeast species for the production of citric acid using glycerol and agro-waste. Fruit samples (orange, lime, lemon and pineapple) were collected from Bodija market in Ibadan. The samples were subjected to microbiological and physicochemical analyses. A total of 43 yeast isolates were recovered from the fruit and 17 isolates had the potential to produce citric acid after screening. Yeast isolates were identified as: Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2. The best incubation period for citric acid production by Candida tropicalis PiB10 was 120 hours (18.02 g/l), highest citric acid production (33.53 g/l) at pH 5.0, maximum citric acid production (20.84 g/l) was at 30°C, Glucose was the best carbon source, yielding 18.00 g/l of citric acid. Yeast extract was the best nitrogen source with citric acid production of 19.20 g/l and the highest production of 19.58 g/l at 200 rpm from glycerol. Meyerozyma guilliermondii LeB1 showed the highest citric acid production at 120 hours of incubation, yielding 17.02 g/l. The best pH was 5.5, yielding 35.90 g/l of citric acid. The best temperature was 30°C, with a production of 15.80 g/l, Glucose was also the preferred carbon source for this isolate, with a production of 20.13 g/l. Yeast extract was the best nitrogen source for Pichia guilliermondii LeB1, yielding 18.85 g/l. At 200 rpm from glycerol, the highest production was 22.37 g/l. This study demonstrated that Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2 yielded high amount of citric acid using glycerol and agro-industrial wastes as substrates.
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    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.
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    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.
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    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.
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    Screening and characterisation of yeast species for citric acid production using glycerol and agro-waste
    (The Nigerian Society for Microbiology (NSM), 2025) Afolabi, F. T.; Adeoye, A. E.
    The present study was aimed to isolate and screen yeast species for the production of citric acid using glycerol and agro-waste. Fruit samples (orange, lime, lemon and pineapple) were collected from Bodija market in Ibadan. The samples were subjected to microbiological and physicochemical analyses. A total of 43 yeast isolates were recovered from the fruit and 17 isolates had the potential to produce citric acid after screening. Yeast isolates were identified as: Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2. The best incubation period for citric acid production by Candida tropicalis PiB10 was 120 hours (18.02 g/l), highest citric acid production (33.53 g/l) at pH 5.0, maximum citric acid production (20.84 g/l) was at 30°C, Glucose was the best carbon source, yielding 18.00 g/l of citric acid. Yeast extract was the best nitrogen source with citric acid production of 19.20 g/l and the highest production of 19.58 g/l at 200 rpm from glycerol. Meyerozyma guilliermondii LeB1 showed the highest citric acid production at 120 hours of incubation, yielding 17.02 g/l. The best pH was 5.5, yielding 35.90 g/l of citric acid. The best temperature was 30°C, with a production of 15.80 g/l, Glucose was also the preferred carbon source for this isolate, with a production of 20.13 g/l. Yeast extract was the best nitrogen source for Pichia guilliermondii LeB1, yielding 18.85 g/l. At 200 rpm from glycerol, the highest production was 22.37 g/l. This study demonstrated that Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2 yielded high amount of citric acid using glycerol and agro-industrial wastes as substrates.
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    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.
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    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.
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    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.
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    Screening and characterisation of yeast species for citric acid production using glycerol and agro-waste
    (The Nigerian Society for Microbiology (NSM), 2025) Afolabi, F. T.; Adeoye, A. E.
    The present study was aimed to isolate and screen yeast species for the production of citric acid using glycerol and agro-waste. Fruit samples (orange, lime, lemon and pineapple) were collected from Bodija market in Ibadan. The samples were subjected to microbiological and physicochemical analyses. A total of 43 yeast isolates were recovered from the fruit and 17 isolates had the potential to produce citric acid after screening. Yeast isolates were identified as: Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2. The best incubation period for citric acid production by Candida tropicalis PiB10 was 120 hours (18.02 g/l), highest citric acid production (33.53 g/l) at pH 5.0, maximum citric acid production (20.84 g/l) was at 30°C, Glucose was the best carbon source, yielding 18.00 g/l of citric acid. Yeast extract was the best nitrogen source with citric acid production of 19.20 g/l and the highest production of 19.58 g/l at 200 rpm from glycerol. Meyerozyma guilliermondii LeB1 showed the highest citric acid production at 120 hours of incubation, yielding 17.02 g/l. The best pH was 5.5, yielding 35.90 g/l of citric acid. The best temperature was 30°C, with a production of 15.80 g/l, Glucose was also the preferred carbon source for this isolate, with a production of 20.13 g/l. Yeast extract was the best nitrogen source for Pichia guilliermondii LeB1, yielding 18.85 g/l. At 200 rpm from glycerol, the highest production was 22.37 g/l. This study demonstrated that Candida tropicalis, Meyerozyma guilliermondii and Candida tropicalis2 yielded high amount of citric acid using glycerol and agro-industrial wastes as substrates.
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    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.