- Email: [email protected]
Effect of the carbon source on the fermentative performance of Dekkera bruxellensis, contaminant yeasts from the alcoholic fermentations
Special Abstracts / Journal of Biotechnology 150S (2010) S1–S576
strategy yielded similar specific productivities when compared to a typical fermentation at 37 ◦ C but with a lower metabolic burden, due to the high percentage of healthy cells at the end of the fermentation. In conclusion, amino acid limitation based strategies seemed to be a suitable approach to be implemented at a large scale level since it is cheaper (does not require any additional energy) and it has proved to be efficient in the amplification of several plasmids. doi:10.1016/j.jbiotec.2010.09.861 [PUB-O.1] Effect of the carbon source on the fermentative performance of Dekkera bruxellensis, contaminant yeasts from the alcoholic fermentations S.R. Ceccato-Antonini ∗ , A.P.G. Bassi, V.R. Reis Universidade Federal de São Carlos, Brazil Keywords: alcoholic fermentation; Dekkera bruxellensis; contaminant yeast; fermentative performance The yeasts Dekkera bruxellensis are important contaminants in alcoholic fermentations for beverage and fuel alcohol production. In the latter very little is known about their role in the process and which conditions may trigger or influence their growth. In this work the effect of the carbon source (glucose or sucrose) on the fermentative performance of three strains of D. bruxellensis was evaluated. The yeasts (isolated from ethanol-producing units) were grown in YEPD medium with cell recycle until enough wet mass was achieved to inoculate three 500-mL Erlenmeyer flasks with 200 mL of final medium volume, in a concentration of 10 g/L of mass (washed in saline solution repeatedly) in each. The fermentation medium was constituted of salts, yeast extract (0.6%) and glucose or sucrose (10%), pH 5.0, and flasks were maintained at 30 ◦ C, 100 rpm for 48 hours. Samples were taken each 12 hours to evaluate pH, alcoholic content (%), Brix (◦ ), cell number (cells/mL) and viability (%). The fermentation rate was slower with sucrose, with alcohol production as much as 20% higher with glucose for two strains. An intense medium acidification was achieved after 48 hours, which should have contributed to the remarkable decrease in the cell viability especially with glucose. Values of pH as low as 1.8-1.9 were observed for all three strains at the end of fermentation. Despite of the low fermentative efficiency (around 1-1.5% of alcohol), in a previous study a similar result was obtained only after 3-4 days of fermentation in sugar cane juice in batch system with cell recycle in static cultures. The carbon source influenced the fermentation rate stimulating acid production but the flask agitation favoring aeration is also an important parameter to be considered in the managing of these yeasts during the fermentation process (Support: Fapesp 09/14617-4 and 09/07061-0). doi:10.1016/j.jbiotec.2010.09.862
S531
[PUB-O.2] Potentiality of phytopathogen-controlling yeasts isolated from sugar cane as growth plant promoters M.M. Rosa 1,2 , S.M. Tauk-Tornisielo 2 , M.L.R. Lopes-Assad 1 , S.R. Ceccato-Antonini 1,∗ 1
Universidade Federal de São Carlos, Brazil Universidade Estadual Paulista, Brazil Keywords: growth plant promoter; biological control; Colletotrichum; yeasts 2
Microorganisms known as growth plant promoters (GPPM) are naturally found in rhizosphere and on plant surfaces, producing substances capable to stimulate the vegetal development by different mechanisms as siderophore and fitohormone production, biological control, resistance induction and mineral solubilization with the release of nutrients in soil solution. Yeasts participate actively in diverse and important biotechnology processes and although they are widely found in agricultural areas, little is known about their function in these environments. The aim of this work was to evaluate the potentiality of yeasts isolated from sugar cane and exhibiting control of fungal phytopathogen development as growth plant promoters and their application in sustainable crop management. Yeasts were isolated from rhizosphere soil and leaves of sugar cane and after a screening process three strains were selected due to the biocontrol of Colletotrichum sublineolum, sorghum pathogen causing anthracnose, by direct antagonism in Petri dish. The yeasts were identified by ITS region sequencing as Torulaspora globosa (strain 1S112, isolated from soil rhizosphere), Rhodotorula globosa (strain 2F32, isolated from leaves) and Candida intermedia (strain 2S02, isolated from leaves). Evaluations of indole acetic acid (auxin fitohormone) and siderophore production as well as in vitro solubilization of phosphate and potassium were taken. Not even a yeast produced siderophore compounds but the strain of T. globosa was able to produce indole acetic acid and solubilize phosphate in vitro. Potassium was significantly released from insoluble rock probably due to the intense acid production. No previous report was found about T. globosa in soil and its function in that habitat. This strain may be a potential organism to be used to promote plant growth, but further studies should be conducted to get a field evaluation of its potential. (Support: CNPq grant) doi:10.1016/j.jbiotec.2010.09.863 [PUB-O.3] Isolation and screening of pentose-fermenting yeasts for the bioethanol production Sandra Regina Ceccato-Antonini 1,∗ , Cristina Martini 2 , Maisa Helena Heluany 1 , Ana Ligia Buzolin 1 , Sâmia Maria TaukTornisielo 2 , Márcia Maria Rosa-Magri 1 1 2
Universidade Federal de São Carlos, Brazil Universidade Estadual Paulista, Brazil
The bioethanol produced from lignocellulosic substrates is different from the first-generation ethanol concerning the technology to release the simple sugars from the biomass and the microorganism to ferment them. Pentoses as xylose and arabinose are not utilized by Saccharomyces cerevisiae, the well-known yeast used in industrial processes. For the production of ethanol from these abundant raw materials a search for yeasts able to ferment the pentoses is required. This work aimed to isolate yeasts from soil and from sugar cane bagasse and juice, using selective media with xylose or
strategy yielded similar specific productivities when compared to a typical fermentation at 37 ◦ C but with a lower metabolic burden, due to the high percentage of healthy cells at the end of the fermentation. In conclusion, amino acid limitation based strategies seemed to be a suitable approach to be implemented at a large scale level since it is cheaper (does not require any additional energy) and it has proved to be efficient in the amplification of several plasmids. doi:10.1016/j.jbiotec.2010.09.861 [PUB-O.1] Effect of the carbon source on the fermentative performance of Dekkera bruxellensis, contaminant yeasts from the alcoholic fermentations S.R. Ceccato-Antonini ∗ , A.P.G. Bassi, V.R. Reis Universidade Federal de São Carlos, Brazil Keywords: alcoholic fermentation; Dekkera bruxellensis; contaminant yeast; fermentative performance The yeasts Dekkera bruxellensis are important contaminants in alcoholic fermentations for beverage and fuel alcohol production. In the latter very little is known about their role in the process and which conditions may trigger or influence their growth. In this work the effect of the carbon source (glucose or sucrose) on the fermentative performance of three strains of D. bruxellensis was evaluated. The yeasts (isolated from ethanol-producing units) were grown in YEPD medium with cell recycle until enough wet mass was achieved to inoculate three 500-mL Erlenmeyer flasks with 200 mL of final medium volume, in a concentration of 10 g/L of mass (washed in saline solution repeatedly) in each. The fermentation medium was constituted of salts, yeast extract (0.6%) and glucose or sucrose (10%), pH 5.0, and flasks were maintained at 30 ◦ C, 100 rpm for 48 hours. Samples were taken each 12 hours to evaluate pH, alcoholic content (%), Brix (◦ ), cell number (cells/mL) and viability (%). The fermentation rate was slower with sucrose, with alcohol production as much as 20% higher with glucose for two strains. An intense medium acidification was achieved after 48 hours, which should have contributed to the remarkable decrease in the cell viability especially with glucose. Values of pH as low as 1.8-1.9 were observed for all three strains at the end of fermentation. Despite of the low fermentative efficiency (around 1-1.5% of alcohol), in a previous study a similar result was obtained only after 3-4 days of fermentation in sugar cane juice in batch system with cell recycle in static cultures. The carbon source influenced the fermentation rate stimulating acid production but the flask agitation favoring aeration is also an important parameter to be considered in the managing of these yeasts during the fermentation process (Support: Fapesp 09/14617-4 and 09/07061-0). doi:10.1016/j.jbiotec.2010.09.862
S531
[PUB-O.2] Potentiality of phytopathogen-controlling yeasts isolated from sugar cane as growth plant promoters M.M. Rosa 1,2 , S.M. Tauk-Tornisielo 2 , M.L.R. Lopes-Assad 1 , S.R. Ceccato-Antonini 1,∗ 1
Universidade Federal de São Carlos, Brazil Universidade Estadual Paulista, Brazil Keywords: growth plant promoter; biological control; Colletotrichum; yeasts 2
Microorganisms known as growth plant promoters (GPPM) are naturally found in rhizosphere and on plant surfaces, producing substances capable to stimulate the vegetal development by different mechanisms as siderophore and fitohormone production, biological control, resistance induction and mineral solubilization with the release of nutrients in soil solution. Yeasts participate actively in diverse and important biotechnology processes and although they are widely found in agricultural areas, little is known about their function in these environments. The aim of this work was to evaluate the potentiality of yeasts isolated from sugar cane and exhibiting control of fungal phytopathogen development as growth plant promoters and their application in sustainable crop management. Yeasts were isolated from rhizosphere soil and leaves of sugar cane and after a screening process three strains were selected due to the biocontrol of Colletotrichum sublineolum, sorghum pathogen causing anthracnose, by direct antagonism in Petri dish. The yeasts were identified by ITS region sequencing as Torulaspora globosa (strain 1S112, isolated from soil rhizosphere), Rhodotorula globosa (strain 2F32, isolated from leaves) and Candida intermedia (strain 2S02, isolated from leaves). Evaluations of indole acetic acid (auxin fitohormone) and siderophore production as well as in vitro solubilization of phosphate and potassium were taken. Not even a yeast produced siderophore compounds but the strain of T. globosa was able to produce indole acetic acid and solubilize phosphate in vitro. Potassium was significantly released from insoluble rock probably due to the intense acid production. No previous report was found about T. globosa in soil and its function in that habitat. This strain may be a potential organism to be used to promote plant growth, but further studies should be conducted to get a field evaluation of its potential. (Support: CNPq grant) doi:10.1016/j.jbiotec.2010.09.863 [PUB-O.3] Isolation and screening of pentose-fermenting yeasts for the bioethanol production Sandra Regina Ceccato-Antonini 1,∗ , Cristina Martini 2 , Maisa Helena Heluany 1 , Ana Ligia Buzolin 1 , Sâmia Maria TaukTornisielo 2 , Márcia Maria Rosa-Magri 1 1 2
Universidade Federal de São Carlos, Brazil Universidade Estadual Paulista, Brazil
The bioethanol produced from lignocellulosic substrates is different from the first-generation ethanol concerning the technology to release the simple sugars from the biomass and the microorganism to ferment them. Pentoses as xylose and arabinose are not utilized by Saccharomyces cerevisiae, the well-known yeast used in industrial processes. For the production of ethanol from these abundant raw materials a search for yeasts able to ferment the pentoses is required. This work aimed to isolate yeasts from soil and from sugar cane bagasse and juice, using selective media with xylose or