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Improvement of ethanol production by ethanol-tolerant Saccharomyces cerevisiae UVNR56.

Thammasittirong SN, Thirasaktana T, Thammasittirong A, Srisodsuk M - Springerplus (2013)

Bottom Line: One ethanol-tolerant mutant, UVNR56, displayed a significantly improved ethanol tolerance in the presence of 15% (v/v) ethanol and showed a considerably higher viability during ethanol fermentation from sugarcane molasses and sugarcane molasses with initial ethanol supplementation.A maximum ethanol concentration produced from molasses medium at 37°C by UVNR56 was 10.3% (v/v), productivity of 1.7 g/l/h and a theoretical yield of 98.7%, while the corresponding values for the wild-type were 8.6% (v/v), 1.4 g/l/h and 83.3%, respectively.In addition, during molasses fermentation under initial supplementation of 5% (v/v) ethanol, the maximum ethanol concentration and productivity of UVNR56 was 25.7% and 42.9% higher than the wild-type, respectively.

View Article: PubMed Central - PubMed

Affiliation: Microbial Biotechnology Unit, Department of Microbiology, Faculty of Liberal Arts and Science, Kasetsart University Kamphaeng Saen Campus, Nakorn Pathom, 73140 Thailand.

ABSTRACT
Ethanol tolerance is one of the important characteristics of ethanol-producing yeast. This study focused on the improvement of ethanol tolerance of Saccharomyces cerevisiae NR1 for enhancing ethanol production by random UV-C mutagenesis. One ethanol-tolerant mutant, UVNR56, displayed a significantly improved ethanol tolerance in the presence of 15% (v/v) ethanol and showed a considerably higher viability during ethanol fermentation from sugarcane molasses and sugarcane molasses with initial ethanol supplementation. A maximum ethanol concentration produced from molasses medium at 37°C by UVNR56 was 10.3% (v/v), productivity of 1.7 g/l/h and a theoretical yield of 98.7%, while the corresponding values for the wild-type were 8.6% (v/v), 1.4 g/l/h and 83.3%, respectively. In addition, during molasses fermentation under initial supplementation of 5% (v/v) ethanol, the maximum ethanol concentration and productivity of UVNR56 was 25.7% and 42.9% higher than the wild-type, respectively.

No MeSH data available.


Comparison of viable cells during cultivation in YPD medium containing 15% (v/v) ethanol of UVNR56 (filled triangle) and the wild-type (filled square). All experiments were performed at 30°C with 100 rpm. Cell samples were taken and spreading serially diluted samples on YPD agar. Colonies were counted after 48 h incubation at 30°C. Data represent the mean ± standard deviation from three independent experiments.
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Fig1: Comparison of viable cells during cultivation in YPD medium containing 15% (v/v) ethanol of UVNR56 (filled triangle) and the wild-type (filled square). All experiments were performed at 30°C with 100 rpm. Cell samples were taken and spreading serially diluted samples on YPD agar. Colonies were counted after 48 h incubation at 30°C. Data represent the mean ± standard deviation from three independent experiments.

Mentions: The results of the shake-flask fermentation of the mutants from our previous UV-C mutant library were that five of 16 colonies fermented in sugarcane molasses medium produced 3-10% more ethanol than the wild-type (NR1) (data not shown). In order to increase ethanol production from sugarcane molasses by improving ethanol tolerance, the selected five mutants were pooled and then subjected to further UV-C mutagenesis. The colonies that grew in molasses medium at the higher ethanol concentration on 12% (v/v) ethanol gradient plate, relative to the wild-type, were selected and analyzed for their ethanol tolerance ability according to the effect of ethanol on yeast viability. One ethanol-tolerant mutant, UVNR56, showed higher numbers of viable cells comparing to the wild-type in the presence of 15% (v/v) ethanol in YPD medium (Figure 1). YPD medium had been used as a growth medium in order to avoid the complexity and adaptation to environmental stresses of sugarcane molasses and to ensure that viability are directly connected with any ethanol effect. The high cell count indicated that UVNR56 possessed improved tolerance against ethanol. This ethanol-tolerant mutant strain retained its tolerant phenotype, even after twenty cycles of growth.Figure 1


Improvement of ethanol production by ethanol-tolerant Saccharomyces cerevisiae UVNR56.

Thammasittirong SN, Thirasaktana T, Thammasittirong A, Srisodsuk M - Springerplus (2013)

Comparison of viable cells during cultivation in YPD medium containing 15% (v/v) ethanol of UVNR56 (filled triangle) and the wild-type (filled square). All experiments were performed at 30°C with 100 rpm. Cell samples were taken and spreading serially diluted samples on YPD agar. Colonies were counted after 48 h incubation at 30°C. Data represent the mean ± standard deviation from three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4320205&req=5

Fig1: Comparison of viable cells during cultivation in YPD medium containing 15% (v/v) ethanol of UVNR56 (filled triangle) and the wild-type (filled square). All experiments were performed at 30°C with 100 rpm. Cell samples were taken and spreading serially diluted samples on YPD agar. Colonies were counted after 48 h incubation at 30°C. Data represent the mean ± standard deviation from three independent experiments.
Mentions: The results of the shake-flask fermentation of the mutants from our previous UV-C mutant library were that five of 16 colonies fermented in sugarcane molasses medium produced 3-10% more ethanol than the wild-type (NR1) (data not shown). In order to increase ethanol production from sugarcane molasses by improving ethanol tolerance, the selected five mutants were pooled and then subjected to further UV-C mutagenesis. The colonies that grew in molasses medium at the higher ethanol concentration on 12% (v/v) ethanol gradient plate, relative to the wild-type, were selected and analyzed for their ethanol tolerance ability according to the effect of ethanol on yeast viability. One ethanol-tolerant mutant, UVNR56, showed higher numbers of viable cells comparing to the wild-type in the presence of 15% (v/v) ethanol in YPD medium (Figure 1). YPD medium had been used as a growth medium in order to avoid the complexity and adaptation to environmental stresses of sugarcane molasses and to ensure that viability are directly connected with any ethanol effect. The high cell count indicated that UVNR56 possessed improved tolerance against ethanol. This ethanol-tolerant mutant strain retained its tolerant phenotype, even after twenty cycles of growth.Figure 1

Bottom Line: One ethanol-tolerant mutant, UVNR56, displayed a significantly improved ethanol tolerance in the presence of 15% (v/v) ethanol and showed a considerably higher viability during ethanol fermentation from sugarcane molasses and sugarcane molasses with initial ethanol supplementation.A maximum ethanol concentration produced from molasses medium at 37°C by UVNR56 was 10.3% (v/v), productivity of 1.7 g/l/h and a theoretical yield of 98.7%, while the corresponding values for the wild-type were 8.6% (v/v), 1.4 g/l/h and 83.3%, respectively.In addition, during molasses fermentation under initial supplementation of 5% (v/v) ethanol, the maximum ethanol concentration and productivity of UVNR56 was 25.7% and 42.9% higher than the wild-type, respectively.

View Article: PubMed Central - PubMed

Affiliation: Microbial Biotechnology Unit, Department of Microbiology, Faculty of Liberal Arts and Science, Kasetsart University Kamphaeng Saen Campus, Nakorn Pathom, 73140 Thailand.

ABSTRACT
Ethanol tolerance is one of the important characteristics of ethanol-producing yeast. This study focused on the improvement of ethanol tolerance of Saccharomyces cerevisiae NR1 for enhancing ethanol production by random UV-C mutagenesis. One ethanol-tolerant mutant, UVNR56, displayed a significantly improved ethanol tolerance in the presence of 15% (v/v) ethanol and showed a considerably higher viability during ethanol fermentation from sugarcane molasses and sugarcane molasses with initial ethanol supplementation. A maximum ethanol concentration produced from molasses medium at 37°C by UVNR56 was 10.3% (v/v), productivity of 1.7 g/l/h and a theoretical yield of 98.7%, while the corresponding values for the wild-type were 8.6% (v/v), 1.4 g/l/h and 83.3%, respectively. In addition, during molasses fermentation under initial supplementation of 5% (v/v) ethanol, the maximum ethanol concentration and productivity of UVNR56 was 25.7% and 42.9% higher than the wild-type, respectively.

No MeSH data available.