scholarly journals Enhancement of Ethanol Fermentation in Saccharomyces cerevisiae Sake Yeast by Disrupting Mitophagy Function

2013 ◽  
Vol 80 (3) ◽  
pp. 1002-1012 ◽  
Author(s):  
Shodai Shiroma ◽  
Lahiru Niroshan Jayakody ◽  
Kenta Horie ◽  
Koji Okamoto ◽  
Hiroshi Kitagaki
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Strain ◽  
Parent Strain ◽  
Ethanol Yield ◽  
Synthetic Medium ◽  
Nutrient Concentrations ◽  
Content Type ◽  
Fermentative Capacity ◽  
Limiting Nutrient ◽  
Biomass Resources

ABSTRACTSaccharomyces cerevisiaesake yeast strain Kyokai no. 7 has one of the highest fermentation rates among brewery yeasts used worldwide; therefore, it is assumed that it is not possible to enhance its fermentation rate. However, in this study, we found that fermentation by sake yeast can be enhanced by inhibiting mitophagy. We observed mitophagy in wild-type sake yeast during the brewing of Ginjo sake, but not when the mitophagy gene (ATG32) was disrupted. During sake brewing, the maximum rate of CO2production and final ethanol concentration generated by theatg32Δ laboratory yeast mutant were 7.50% and 2.12% higher than those of the parent strain, respectively. This mutant exhibited an improved fermentation profile when cultured under limiting nutrient concentrations such as those used during Ginjo sake brewing as well as in minimal synthetic medium. The mutant produced ethanol at a concentration that was 2.76% higher than the parent strain, which has significant implications for industrial bioethanol production. The ethanol yield of theatg32Δ mutant was increased, and its biomass yield was decreased relative to the parent sake yeast strain, indicating that theatg32Δ mutant has acquired a high fermentation capability at the cost of decreasing biomass. Because natural biomass resources often lack sufficient nutrient levels for optimal fermentation, mitophagy may serve as an important target for improving the fermentative capacity of brewery yeasts.

scholarly journals New Lager Brewery Strains Obtained by Crossing Techniques Using Cachaça (Brazilian Spirit) Yeasts

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Bruna Inez Carvalho Figueiredo ◽  
Margarete Alice Fontes Saraiva ◽  
Paloma Patrick de Souza Pimenta ◽  
Miriam Conceição de Souza Testasicca ◽  
Geraldo Magela Santos Sampaio ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperature ◽  
Yeast Strain ◽  
Genetically Modified ◽  
Acetate Esters ◽  
Content Type ◽  
Yeast Strains ◽  
Lager Beer ◽  
New Yeast ◽  
Beer Production

ABSTRACT The development of hybrids has been an effective approach to generate novel yeast strains with optimal technological profile for use in beer production. This study describes the generation of a new yeast strain for lager beer production by direct mating between two Saccharomyces cerevisiae strains isolated from cachaça distilleries: one that was strongly flocculent, and the other with higher production of acetate esters. The first step in this procedure was to analyze the sporulation ability and reproductive cycle of strains belonging to a specific collection of yeasts isolated from cachaça fermentation vats. Most strains showed high rates of sporulation, spore viability, and homothallic behavior. In order to obtain new yeast strains with desirable properties useful for lager beer production, we compare haploid-to-haploid and diploid-to-diploid mating procedures. Moreover, an assessment of parental phenotype traits showed that the segregant diploid C2-1d generated from a diploid-to-diploid mating experiment showed good fermentation performance at low temperature, high flocculation capacity, and desirable production of acetate esters that was significantly better than that of one type lager strain. Therefore, strain C2-1d might be an important candidate for the production of lager beer, with distinct fruit traces and originating using a non-genetically modified organism (GMO) approach. IMPORTANCE Recent work has suggested the utilization of hybridization techniques for the generation of novel non-genetically modified brewing yeast strains with combined properties not commonly found in a unique yeast strain. We have observed remarkable traits, especially low temperature tolerance, maltotriose utilization, flocculation ability, and production of volatile aroma compounds, among a collection of Saccharomyces cerevisiae strains isolated from cachaça distilleries, which allow their utilization in the production of beer. The significance of our research is in the use of breeding/hybridization techniques to generate yeast strains that would be appropriate for producing new lager beers by exploring the capacity of cachaça yeast strains to flocculate and to ferment maltose at low temperature, with the concomitant production of flavoring compounds.

scholarly journals Ethanol Production from Nondetoxified Dilute-Acid Lignocellulosic Hydrolysate by Cocultures of Saccharomyces cerevisiae Y5 and Pichia stipitis CBS6054

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Ping Wan ◽  
Dongmei Zhai ◽  
Zhen Wang ◽  
Xiushan Yang ◽  
Shen Tian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Production ◽  
Ethanol Concentration ◽  
Ethanol Yield ◽  
Synthetic Medium ◽  
Pichia Stipitis ◽  
Dilute Acid ◽  
Acid Hydrolysate ◽  
Issatchenkia Orientalis ◽  
Final Ethanol Concentration

Saccharomyces cerevisiae Y5 (CGMCC no. 2660) and Issatchenkia orientalis Y4 (CGMCC no. 2159) were combined individually with Pichia stipitis CBS6054 to establish the cocultures of Y5 + CBS6054 and Y4 + CBS6054. The coculture Y5 + CBS6054 effectively metabolized furfural and HMF and converted xylose and glucose mixture to ethanol with ethanol concentration of 16.6 g/L and ethanol yield of 0.46 g ethanol/g sugar, corresponding to 91.2% of the maximal theoretical value in synthetic medium. Accordingly, the nondetoxified dilute-acid hydrolysate was used to produce ethanol by co-culture Y5 + CBS6054. The co-culture consumed glucose along with furfural and HMF completely in 12 h, and all xylose within 96 h, resulting in a final ethanol concentration of 27.4 g/L and ethanol yield of 0.43 g ethanol/g sugar, corresponding to 85.1% of the maximal theoretical value. The results indicated that the co-culture of Y5 + CBS6054 was a satisfying combination for ethanol production from non-detoxified dilute-acid lignocellulosic hydrolysates. This co-culture showed a promising prospect for industrial application.

Ethanol Production from Different Substrates by a Flocculent Saccharomyces cerevisiae Strain

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
José Duarte ◽  
Vera Lourenço ◽  
Belina Ribeiro ◽  
Maria Céu Saagua ◽  
Joana Pereira ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Production ◽  
Yeast Strain ◽  
Fossil Fuels ◽  
Ethanol Yield ◽  
Corn Fiber ◽  
Production Costs ◽  
Raw Material ◽  
Continuous Reactor ◽  
Different Strains

During the last years there has been an increasing interest in using ethanol as a substitute for fossil fuels. The bioethanol used today is mainly produced from sugar cane and cereals, but reducing the production costs of ethanol is still crucial for a viable economic process. Cellulose from vegetable biomass will be the next cheap raw material for second generation fuel ethanol production and agricultural by-products with a low commercial value, as corn stover, corn fiber and cane bagasses would become an attractive feedstock for bioethanol production.In this study, different strains of Saccharomyces cerevisiae have been screened for the ability of bioethanol production. Yeasts were grown in a synthetic liquid medium containing sucrose in batch regime and the growth rates, ethanol and biomass productions were determined as well as their growth ability in cane molasses.The results indicate that a flocculent yeast, isolated in our lab and designated by strain F, was the most promising yeast strain among those tested for continuous ethanol production. This strain was isolated from corn hydrolysates, obtained from a Portuguese distillery facility (DVT, Torres Novas, Portugal) showing highest growth rate (0.49h-1), highest ethanol yield (0.35g/g) and high flocculation capacity.The study on ethanol production in continuous reactor process with the selected yeast strain (strain F) was made on sucrose and cane molasses at different dilution rates (0.05-0.42 h-1). A steady flocculating yeast fluidized bed reactor system was established allowing the functioning of the reactor for 1000 h. Data shows that when the dilution rate rose to 0.42h-1, the highest productivity (20g/Lh) was obtained attaining an ethanol concentration in the reactor of 47g/L for sucrose and molasses media.

scholarly journals Cofermentation of Cellobiose and Galactose by an Engineered Saccharomyces cerevisiae Strain

2011 ◽  
Vol 77 (16) ◽  
pp. 5822-5825 ◽  
Author(s):  
Suk-Jin Ha ◽  
Qiaosi Wei ◽  
Soo Rin Kim ◽  
Jonathan M. Galazka ◽  
Jamie Cate ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Neurospora Crassa ◽  
Plant Biomass ◽  
Ethanol Yield ◽  
Content Type ◽  
Marine Plant ◽  
Cellodextrin Transporter ◽  
Engineered Saccharomyces Cerevisiae

ABSTRACTWe demonstrate improved ethanol yield and productivity through cofermentation of cellobiose and galactose by an engineeredSaccharomyces cerevisiaestrain expressing genes coding for cellodextrin transporter (cdt-1) and intracellular β-glucosidase (gh1-1) fromNeurospora crassa. Simultaneous fermentation of cellobiose and galactose can be applied to producing biofuels from hydrolysates of marine plant biomass.

scholarly journals Directed Evolution of Xylose Isomerase for Improved Xylose Catabolism and Fermentation in the Yeast Saccharomyces cerevisiae

2012 ◽  
Vol 78 (16) ◽  
pp. 5708-5716 ◽  
Author(s):  
Sun-Mi Lee ◽  
Taylor Jellison ◽  
Hal S. Alper
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Production ◽  
Directed Evolution ◽  
Ethanol Yield ◽  
Xylose Isomerase ◽  
Mutant Enzyme ◽  
Xylose Utilization ◽  
Xylose Consumption ◽  
Content Type ◽  
Consumption Rates

ABSTRACTThe heterologous expression of a highly functional xylose isomerase pathway inSaccharomyces cerevisiaewould have significant advantages for ethanol yield, since the pathway bypasses cofactor requirements found in the traditionally used oxidoreductase pathways. However, nearly all reported xylose isomerase-based pathways inS. cerevisiaesuffer from poor ethanol productivity, low xylose consumption rates, and poor cell growth compared with an oxidoreductase pathway and, additionally, often require adaptive strain evolution. Here, we report on the directed evolution of thePiromycessp. xylose isomerase (encoded byxylA) for use in yeast. After three rounds of mutagenesis and growth-based screening, we isolated a variant containing six mutations (E15D, E114G, E129D, T142S, A177T, and V433I) that exhibited a 77% increase in enzymatic activity. When expressed in a minimally engineered yeast host containing agre3knockout andtal1andXKS1overexpression, the strain expressing this mutant enzyme improved its aerobic growth rate by 61-fold and both ethanol production and xylose consumption rates by nearly 8-fold. Moreover, the mutant enzyme enabled ethanol production by these yeasts under oxygen-limited fermentation conditions, unlike the wild-type enzyme. Under microaerobic conditions, the ethanol production rates of the strain expressing the mutant xylose isomerase were considerably higher than previously reported values for yeast harboring a xylose isomerase pathway and were also comparable to those of the strains harboring an oxidoreductase pathway. Consequently, this study shows the potential to evolve a xylose isomerase pathway for more efficient xylose utilization.

scholarly journals Cocoa’s Residual Honey: Physicochemical Characterization and Potential as a Fermentative Substrate by Saccharomyces cerevisiae AWRI726

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Paula Bacelar Leite ◽  
Wanderson Mariano Machado ◽  
Alaíse Gil Guimarães ◽  
Giovani Brandão Mafra de Carvalho ◽  
Karina Teixeira Magalhães-Guedes ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Crude Protein ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Starter Culture ◽  
Physicochemical Characterization ◽  
Specific Cell ◽  
Minor Components ◽  
Fermentative Capacity ◽  
Commercial Applications

This study aims to characterize the physicochemical properties of cocoa’s residual honey and evaluate its fermentative capacity as a substrate, using Saccharomyces cerevisiae AWRI726 as the starter culture for alcoholic fermentation. The research hypothesis was that cocoa’s residual honey can be used for the production of fermented beverages. Cocoa’s honey has 14.14 g.100 mL−1 of dry material, containing 11.80 g.100 mL−1 of carbohydrates and 1.20% crude protein, in addition to other minor components, such as pectin, lipids, and Fe, Mn, Na, and Zn, with a carbon-to-nitrogen (C/N) ratio (9.8) most suitable for fermentation. Fermentation at 20°C for 240 hours produced a liquid with 16% v/v ethanol (14 g.L−1 in 144 h). However, 24 hours of fermentation produced the maximum ethanol yield (0.373 g.g−1) and volumetric productivity (0.168 g.L−1.h−1), which were associated with a significant increase in the specific cell growth rate. Saccharomyces cerevisiae AWR1726 performed satisfactorily in the alcoholic fermentation of cocoa’s residual honey, similar to that observed in other fruit beverages, thus suggesting the suitability of cocoa’s residual honey for future commercial applications.

scholarly journals Improving Acetic Acid and Furfural Resistance of Xylose-Fermenting Saccharomyces cerevisiae Strains by Regulating Novel Transcription Factors Revealed via Comparative Transcriptomic Analysis

2021 ◽  
Vol 87 (10) ◽  
Author(s):  
Bo Li ◽  
Li Wang ◽  
Ya-Jing Wu ◽  
Zi-Yuan Xia ◽  
Bai-Xue Yang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Transcription Factors ◽  
Ethanol Yield ◽  
Regulation Mechanism ◽  
Lignocellulosic Hydrolysate ◽  
Inhibitor Tolerance ◽  
Xylose Consumption ◽  
Content Type ◽  
Beneficial Effects

ABSTRACT Acetic acid and furfural are the two prevalent inhibitors coexisting with glucose and xylose in lignocellulosic hydrolysate. The transcriptional regulations of Saccharomyces cerevisiae in response to acetic acid (Aa), furfural (Fur), and the mixture of acetic acid and furfural (Aa_Fur) were revealed during mixed glucose and xylose fermentation. Carbohydrate metabolism pathways were significantly enriched in response to Aa, while pathways of xenobiotic biodegradation and metabolism were significantly enriched in response to Fur. In addition to these pathways, other pathways were activated in response to Aa_Fur, i.e., cofactor and vitamin metabolism and lipid metabolism. Overexpression of Haa1p or Tye7p improved xylose consumption rates by nearly 50%, while the ethanol yield was enhanced by nearly 8% under acetic acid and furfural stress conditions. Co-overexpression of Haa1p and Tye7p resulted in a 59% increase in xylose consumption rate and a 12% increase in ethanol yield, revealing the beneficial effects of Haa1p and Tye7p on improving the tolerance of yeast to mixed acetic acid and furfural. IMPORTANCE Inhibitor tolerance is essential for S. cerevisiae when fermenting lignocellulosic hydrolysate with various inhibitors, including weak acids, furans, and phenols. The details regarding how xylose-fermenting S. cerevisiae strains respond to multiple inhibitors during fermenting mixed glucose and xylose are still unknown. This study revealed the transcriptional regulation mechanism of an industrial xylose-fermenting S. cerevisiae strain in response to acetic acid and furfural. The transcription factor Haa1p was found to be involved in both acetic acid and furfural tolerance. In addition to Haa1p, four other transcription factors, Hap4p, Yox1p, Tye7p, and Mga1p, were identified as able to improve the resistance of yeast to these two inhibitors. This study underscores the feasibility of uncovering effective transcription factors for constructing robust strains for lignocellulosic bioethanol production.

scholarly journals Fermentation Temperature Modulates Phosphatidylethanolamine and Phosphatidylinositol Levels in the Cell Membrane of Saccharomyces cerevisiae

2013 ◽  
Vol 79 (17) ◽  
pp. 5345-5356 ◽  
Author(s):  
Clark M. Henderson ◽  
Wade F. Zeno ◽  
Larry A. Lerno ◽  
Marjorie L. Longo ◽  
David E. Block
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Membrane ◽  
Lipid Composition ◽  
Yeast Strain ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Content Type ◽  
Fermentation Temperature ◽  
Yeast Strains ◽  
Cell Membrane Fluidity

ABSTRACTDuring alcoholic fermentation,Saccharomyces cerevisiaeis exposed to a host of environmental and physiological stresses. Extremes of fermentation temperature have previously been demonstrated to induce fermentation arrest under growth conditions that would otherwise result in complete sugar utilization at “normal” temperatures and nutrient levels. Fermentations were carried out at 15°C, 25°C, and 35°C in a defined high-sugar medium using threeSaccharomyces cerevisiaestrains with diverse fermentation characteristics. The lipid composition of these strains was analyzed at two fermentation stages, when ethanol levels were low early in stationary phase and in late stationary phase at high ethanol concentrations. Several lipids exhibited dramatic differences in membrane concentration in a temperature-dependent manner. Principal component analysis (PCA) was used as a tool to elucidate correlations between specific lipid species and fermentation temperature for each yeast strain. Fermentations carried out at 35°C exhibited very high concentrations of several phosphatidylinositol species, whereas at 15°C these yeast strains exhibited higher levels of phosphatidylethanolamine and phosphatidylcholine species with medium-chain fatty acids. Furthermore, membrane concentrations of ergosterol were highest in the yeast strain that experienced stuck fermentations at all three temperatures. Fluorescence anisotropy measurements of yeast cell membrane fluidity during fermentation were carried out using the lipophilic fluorophore diphenylhexatriene. These measurements demonstrate that the changes in the lipid composition of these yeast strains across the range of fermentation temperatures used in this study did not significantly affect cell membrane fluidity. However, the results from this study indicate that fermentingS. cerevisiaemodulates its membrane lipid composition in a temperature-dependent manner.

scholarly journals The Cytosolic pH of Individual Saccharomyces cerevisiae Cells Is a Key Factor in Acetic Acid Tolerance

2015 ◽  
Vol 81 (22) ◽  
pp. 7813-7821 ◽  
Author(s):  
Miguel Fernández-Niño ◽  
Maribel Marquina ◽  
Steve Swinnen ◽  
Boris Rodríguez-Porrata ◽  
Elke Nevoigt ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Synthetic Medium ◽  
Acid Tolerance ◽  
Population Level ◽  
Acetic Acid Tolerance ◽  
Cytosolic Ph ◽  
Content Type ◽  
Key Factor ◽  
The Difference

ABSTRACTIt was shown recently that individual cells of an isogenicSaccharomyces cerevisiaepopulation show variability in acetic acid tolerance, and this variability affects the quantitative manifestation of the trait at the population level. In the current study, we investigated whether cell-to-cell variability in acetic acid tolerance could be explained by the observed differences in the cytosolic pHs of individual cells immediately before exposure to the acid. Results obtained with cells of the strain CEN.PK113-7D in synthetic medium containing 96 mM acetic acid (pH 4.5) showed a direct correlation between the initial cytosolic pH and the cytosolic pH drop after exposure to the acid. Moreover, only cells with a low initial cytosolic pH, which experienced a less severe drop in cytosolic pH, were able to proliferate. A similar correlation between initial cytosolic pH and cytosolic pH drop was also observed in the more acid-tolerant strain MUCL 11987-9. Interestingly, a fraction of cells in the MUCL 11987-9 population showed initial cytosolic pH values below the minimal cytosolic pH detected in cells of the strain CEN.PK113-7D; consequently, these cells experienced less severe drops in cytosolic pH. Although this might explain in part the difference between the two strains with regard to the number of cells that resumed proliferation, it was observed that all cells from strain MUCL 11987-9 were able to proliferate, independently of their initial cytosolic pH. Therefore, other factors must also be involved in the greater ability of MUCL 11987-9 cells to endure strong drops in cytosolic pH.

scholarly journals Increasing Anaerobic Acetate Consumption and Ethanol Yields in Saccharomyces cerevisiae with NADPH-Specific Alcohol Dehydrogenase

2015 ◽  
Vol 81 (23) ◽  
pp. 8108-8117 ◽  
Author(s):  
Brooks M. Henningsen ◽  
Shuen Hon ◽  
Sean F. Covalla ◽  
Carolina Sonu ◽  
D. Aaron Argyros ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Alcohol Dehydrogenase ◽  
Ethanol Yield ◽  
Pentose Phosphate ◽  
Wild Type ◽  
Bifidobacterium Adolescentis ◽  
Acetaldehyde Dehydrogenase ◽  
Content Type ◽  
Sugar Fermentation ◽  
Ethanol Yields

ABSTRACTSaccharomyces cerevisiaehas recently been engineered to use acetate, a primary inhibitor in lignocellulosic hydrolysates, as a cosubstrate during anaerobic ethanolic fermentation. However, the original metabolic pathway devised to convert acetate to ethanol uses NADH-specific acetylating acetaldehyde dehydrogenase and alcohol dehydrogenase and quickly becomes constrained by limited NADH availability, even when glycerol formation is abolished. We present alcohol dehydrogenase as a novel target for anaerobic redox engineering ofS. cerevisiae. Introduction of an NADPH-specific alcohol dehydrogenase (NADPH-ADH) not only reduces the NADH demand of the acetate-to-ethanol pathway but also allows the cell to effectively exchange NADPH for NADH during sugar fermentation. Unlike NADH, NADPH can be freely generated under anoxic conditions, via the oxidative pentose phosphate pathway. We show that an industrial bioethanol strain engineered with the original pathway (expressing acetylating acetaldehyde dehydrogenase fromBifidobacterium adolescentisand with deletions of glycerol-3-phosphate dehydrogenase genesGPD1andGPD2) consumed 1.9 g liter−1acetate during fermentation of 114 g liter−1glucose. Combined with a decrease in glycerol production from 4.0 to 0.1 g liter−1, this increased the ethanol yield by 4% over that for the wild type. We provide evidence that acetate consumption in this strain is indeed limited by NADH availability. By introducing an NADPH-ADH fromEntamoeba histolyticaand with overexpression ofACS2andZWF1, we increased acetate consumption to 5.3 g liter−1and raised the ethanol yield to 7% above the wild-type level.

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