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Shan C, Xia T, Liu J, Wang Y, Bai P, Xu L, Li Z, Zhao J, Bao X. The impacts of nicotinamide and inositol on the available cells and product performance of industrial baker's yeasts. BIORESOUR BIOPROCESS 2023; 10:41. [PMID: 38647809 PMCID: PMC10991249 DOI: 10.1186/s40643-023-00661-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/25/2023] [Indexed: 04/25/2024] Open
Abstract
A suitable nutrient supply, especially of vitamins, is very significant for the deep display of the inherent genetic properties of microorganisms. Here, using the chemically defined minimal medium (MM) for yeast, nicotinamide and inositol were confirmed to be more beneficial for the performance of two industrial baker's yeasts, a conventional and a high-sugar-tolerant strain. Increasing nicotinamide or inositol to proper levels could enhance the both strains on cell growth and activity and product performance, including trehalose accumulation and leavening performance. The activity of key enzymes (PCK, TPS) and the content of intermediate metabolites (G6P, UDPG) in the trehalose synthesis pathway were promoted by a moderate supply of nicotinamide and inositol. That were also proved that an appropriate amount of niacinamide promoted the transcription of longevity-related genes (PNC1, SIR2), and the proper concentration of inositol altered the phospholipid composition in cells, namely, phosphatidylinositol and phosphatidyl choline. Furthermore, the cell growth and the leavening performance of the both strains were promoted after adjusting inositol to choline to the proper ratio, resulting directly in content changes of phosphatidylinositol and phosphatidyl choline in the cells. While the two strains responded to the different proper ratio of inositol to choline probably due to their specific physiological characteristics. Such beneficial effects of increased nicotinamide levels were confirmed in natural media, molasses and corn starch hydrolyzed sugar media. Meanwhile, such adjustment of inositol to choline ratio could lessen the inhibition of excess inositol on cell growth of the two tested strains in corn starch hydrolyzed sugar media. However, in molasse, such phenomenon was not observed probably since there was higher Ca2+ in it. The results indicated that the effects of nutrient factors, such as vitamins, on cell growth and other properties found out from the simple chemically defined minimal medium were an effective measure to use in improving the recipe of natural media at least for baker's yeast.
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Affiliation(s)
- Chengpeng Shan
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Tianqing Xia
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Jiao Liu
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China.
- Shandong Shouguang Juneng Golden Corn Co., Ltd, Shouguang, 262711, Shandong, People's Republic of China.
| | - Ying Wang
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Penggang Bai
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Lili Xu
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Zailu Li
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
| | - Jianzhi Zhao
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China.
| | - Xiaoming Bao
- State Key Laboratory of Biobased Material and Green Papermaking, School of Bioengineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, Shandong, People's Republic of China
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Dymond MK. A Membrane Biophysics Perspective on the Mechanism of Alcohol Toxicity. Chem Res Toxicol 2023. [PMID: 37186813 DOI: 10.1021/acs.chemrestox.3c00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Motivations for understanding the underlying mechanisms of alcohol toxicity range from economical to toxicological and clinical. On the one hand, acute alcohol toxicity limits biofuel yields, and on the other hand, acute alcohol toxicity provides a vital defense mechanism to prevent the spread of disease. Herein the role that stored curvature elastic energy (SCE) in biological membranes might play in alcohol toxicity is discussed, for both short and long-chain alcohols. Structure-toxicity relationships for alcohols ranging from methanol to hexadecanol are collated, and estimates of alcohol toxicity per alcohol molecule in the cell membrane are made. The latter reveal a minimum toxicity value per molecule around butanol before alcohol toxicity per molecule increases to a maximum around decanol and subsequently decreases again. The impact of alcohol molecules on the lamellar to inverse hexagonal phase transition temperature (TH) is then presented and used as a metric to assess the impact of alcohol molecules on SCE. This approach suggests the nonmonotonic relationship between alcohol toxicity and chain length is consistent with SCE being a target of alcohol toxicity. Finally, in vivo evidence for SCE-driven adaptations to alcohol toxicity in the literature are discussed.
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Affiliation(s)
- Marcus K Dymond
- Chemistry Research and Enterprise Group, University of Brighton, Huxley Building, Lewes Road, Brighton BN2 4GJ, United Kingdom
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Zheng ZY, Xie G, Tan GL, Liu WL. Proteolysis modification targeting protein corona affects ultrasound-induced membrane homeostasis of saccharomyces cerevisiae: Analysis of lipid relative contributions on membrane properties. Front Microbiol 2023; 14:1082666. [PMID: 36778851 PMCID: PMC9909265 DOI: 10.3389/fmicb.2023.1082666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/09/2023] [Indexed: 01/27/2023] Open
Abstract
Introduction Protein corona (PCN) adsorbed on the surface of nanoparticles has brought new research perspectives for the interaction between nanoparticles and microorganisms. In this study, the responses of saccharomyces cerevisiae' membrane lipid composition, the average length of the fatty acyl chains and the average number of unsaturation of fatty acids to ultrasound combined with nano-Fe3O4@PCN with time-limited proteolysis (nano-Fe3O4@TLP-PCN) was investigated. Methods Lipidomic data was obtained using Ultra-high performance liquid chromatography coupled with a Q-Exactive plus mass spectrometer. The membrane potential, proton motive force assay and the membrane lipid oxidation were measured using Di-BAC4(3), DISC3(5) and C11-BODIPY581/591 as the probes. Combined with the approach of feasible virtual samples generation, the back propagation artificial neural network (BP-ANN) model was adopted to establish the mapping relationship between lipids and membrane properties. Results The time-limited proteolysis targeting wheat PCN-coated Fe3O4 nanoparticles resulted in regular changes of hydrodynamic diameters, ζ-potentials, and surface hydrophobicity. In addition, with the prolongation of PCN proteolysis time, disturbances of 3 S.cerevisiae membrane characteristics, and membrane lipidomic remodeling in response to ultrasound+ nano-Fe3O4@PCN were observed. The analysis of relative importance which followed revealed that ergosterol, phosphatidylserine, and phosphatidylinositol phosphate had the greatest influence on membrane potential. For membrane lipid oxidation, ceramide, phosphatidylethanolamine, and sitosterol ester contribute 16.2, 14.9, and 13.1%, respectively. The relative contributions of six lysolecithins to the dissipation of proton motive force remained limited. Discussion An adaptation mechanism of cell membrane to proteolyzed PCN, wherein lipidome remodeling could preserved functional membrane phenotypes was revealed. Furthermore, it is highlighted that the relative importances of SiE, Cer, PE and PIP in determining membrane potential, PMF dissipation and membrane lipid oxidation by establishing FVSG-BP-ANN model.
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Wu N, Xing M, Chen Y, Zhang C, Li Y, Song P, Xu Q, Liu H, Huang H. Improving the productivity of malic acid by alleviating oxidative stress during Aspergillus niger fermentation. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:151. [PMID: 36581946 PMCID: PMC9801644 DOI: 10.1186/s13068-022-02250-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/15/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND As an attractive platform chemical, malic acid has been commonly used in the food, feed and pharmaceutical field. Microbial fermentation of biobased sources to produce malic acid has attracted great attention because it is sustainable and environment-friendly. However, most studies mainly focus on improving yield and ignore shortening fermentation time. A long fermentation period means high cost, and hinders the industrial applications of microbial fermentation. Stresses, especially oxidative stress generated during fermentation, inhibit microbial growth and production, and prolong fermentation period. Previous studies have shown that polypeptides could effectively relieve stresses, but the underlying mechanisms were poorly understood. RESULTS In this study, polypeptides (especially elastin peptide) addition improves the productivity of malic acid in A. niger, resulting in shortening of fermentation time from 120 to 108 h. Transcriptome and biochemical analyses demonstrated that both antioxidant enzyme-mediated oxidative stress defense system, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and nonenzymatic antioxidant system, such as glutathione, were enhanced in the presence of elastin peptide, suggesting elastin peptide relieving oxidative stresses is involved in many pathways. In order to further investigate the relationship between oxidative stress defense and malic acid productivity, we overexpressed three enzymes (Sod1, CAT, Tps1) related to oxidation resistance in A. niger, respectively, and these resulting strains display varying degree of improvement in malic acid productivity. Especially, the strain overexpressing the Sod1 gene achieved a malate titer of 91.85 ± 2.58 g/L in 96 h, corresponding to a productivity of 0.96 g/L/h, which performs better than elastin peptide addition. CONCLUSIONS Our investigation provides an excellent reference for alleviating the stress of the fungal fermentation process and improving fermentation efficiency.
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Affiliation(s)
- Na Wu
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China ,grid.260474.30000 0001 0089 5711College of Life Sciences, Nanjing Normal University, Nanjing, 210046 China
| | - Mingyan Xing
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China
| | - Yaru Chen
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China
| | - Chi Zhang
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China
| | - Yingfeng Li
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China ,grid.260474.30000 0001 0089 5711College of Life Sciences, Nanjing Normal University, Nanjing, 210046 China
| | - Ping Song
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China
| | - Qing Xu
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China
| | - Hao Liu
- grid.413109.e0000 0000 9735 6249Tianjin Engineering Research Center of Microbial Metabolism and Fermentation Process Control, Tianjin University of Science & Technology, Tianjin, 300457 China
| | - He Huang
- grid.260474.30000 0001 0089 5711School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, 210023 China ,grid.412022.70000 0000 9389 5210College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, 211800 China
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Yang T, Zhang S, Li L, Tian J, Li X, Pan Y. Screening and transcriptomic analysis of the ethanol-tolerant mutant Saccharomyces cerevisiae YN81 for high-gravity brewing. Front Microbiol 2022; 13:976321. [PMID: 36090078 PMCID: PMC9453260 DOI: 10.3389/fmicb.2022.976321] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
Ethanol stress is one of the major limiting factors for high-gravity brewing. Breeding of yeast strain with high ethanol tolerance, and revealing the ethanol tolerance mechanism of Saccharomyces cerevisiae is of great significance to the production of high-gravity beer. In this study, the mutant YN81 was obtained by ultraviolet-diethyl sulfate (UV-DES) cooperative mutagenesis from parental strain CS31 used in high-gravity craft beer brewing. The ethanol tolerance experiment results showed that cell growth and viability of YN81 were significantly greater than that of CS31 under ethanol stress. The ethanol tolerance mechanisms of YN81 were studied through observation of cell morphology, intracellular trehalose content, and transcriptomic analysis. Results from scanning electron microscope (SEM) showed alcohol toxicity caused significant changes in the cell morphology of CS31, while the cell morphology of YN81 changed slightly, indicating the cell morphology of CS31 got worse (the formation of hole and cell wrinkle). In addition, compared with ethanol-free stress, the trehalose content of YN81 and CS31 increased dramatically under ethanol stress, but there was no significant difference between YN81 and CS31, whether with or without ethanol stress. GO functional annotation analysis showed that under alcohol stress, the number of membrane-associated genes in YN81 was higher than that without alcohol stress, as well as CS31, while membrane-associated genes in YN81 were expressed more than CS31 under alcohol stress. KEGG functional enrichment analysis showed unsaturated fatty acid synthesis pathways and amino acid metabolic pathways were involved in ethanol tolerance of YN81. The mutant YN81 and its ethanol tolerance mechanism provide an optimal strain and theoretical basis for high-gravity craft beer brewing.
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Adaptation of Ancient Techniques to Recreate ‘Wines’ and ‘Beverages’ Using Withered Grapes of Muscat of Alexandria. FERMENTATION 2022. [DOI: 10.3390/fermentation8020085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The production of wines using ancient techniques is a present trend with commercial interest among consumers valorising their historical background. Therefore, the objective of the present work was to recreate wines and piquettes produced from dehydrated grapes, vinified according to the techniques described in classical Roman agricultural manuals. Muscat of Alexandria grapes were harvested and subjected to greenhouse drying under ambient temperature for 7 days, during the 2020 and 2021 harvests. When weight loss was approximately 30%, grapes were processed according to different protocols, including a rehydration step using saltwater or white wine (2020 harvest). Fermentation was conducted with the addition of commercial yeast without sulphur dioxide supplementation. The piquettes were obtained from the pressed pomaces diluted with water solution (5 g/L tartaric acid). The 2020 wines showed alcoholic content and residual sugar ranging from 14.8 to 17.0% (v/v), and 0.8 g/L to 18 g/L, respectively. Volatile acidity was less than 1 g/L (as acetic acid) in all wines, except for the fermentation of crushed grapes alone, which yielded 2.3 g/L volatile acidity. The fermentation of dehydrated crushed grapes in the semi-industrial trial run in the harvest of 2021 yielded 1.1 g/L volatile acidity. The piquettes analysis showed ethanol ranging from 10.2% (v/v) to 16.0% (v/v), reducing substances less than 2 g/L and volatile acidity less than 0.8 g/L. Overall, the physicochemical analysis showed that it was possible to recreate ancient winemaking techniques that may be further improved to produce commercially and legally acceptable wines.
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Matsuda F, Komori S, Yamada Y, Hara D, Okahashi N. Data Processing of Product Ion Spectra: Quality Improvement by Averaging Multiple Similar Spectra of Small Molecules. Mass Spectrom (Tokyo) 2022; 11:A0106. [PMID: 36713802 PMCID: PMC9853114 DOI: 10.5702/massspectrometry.a0106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
In metabolomics studies using high-resolution mass spectrometry (MS), a set of product ion spectra is comprehensively acquired from observed ions using the data-dependent acquisition (DDA) mode of various tandem MS. However, especially for low-intensity signals, it is sometimes difficult to distinguish artifact signals from true fragment ions derived from a precursor ion. Inadequate precision in the measured m/z value is also one of the bottlenecks to narrowing down the candidate compositional formula. In this study, we report that averaging multiple product ion spectra can improve m/z precision as well as the reliability of fragment ions that are observed in such spectra. A graph-based method was applied to cluster a set of similar spectra from multiple DDA data files resulting in creating an averaged product-ion spectrum. The error levels for the m/z values declined following the central limit theorem, which allowed us to reduce the number of candidate compositional formulas. The improved reliability and precision of the averaged spectra will contribute to a more efficient annotation of product ion spectral data.
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Affiliation(s)
- Fumio Matsuda
- Graduate School of Information Science and Technology, Osaka University, Osaka, Japan,Osaka University Shimadzu Omics Innovation Research Laboratories, Osaka University, Osaka, Japan,Correspondence to: Fumio Matsuda, Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1–5 Yamadaoka, Suita, Osaka 565–0871, Japan, e-mail:
| | - Shuka Komori
- Graduate School of Information Science and Technology, Osaka University, Osaka, Japan
| | - Yuki Yamada
- Graduate School of Information Science and Technology, Osaka University, Osaka, Japan
| | - Daiki Hara
- Graduate School of Information Science and Technology, Osaka University, Osaka, Japan
| | - Nobuyuki Okahashi
- Graduate School of Information Science and Technology, Osaka University, Osaka, Japan,Osaka University Shimadzu Omics Innovation Research Laboratories, Osaka University, Osaka, Japan
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Scott WT, Smid EJ, Block DE, Notebaart RA. Metabolic flux sampling predicts strain-dependent differences related to aroma production among commercial wine yeasts. Microb Cell Fact 2021; 20:204. [PMID: 34674718 PMCID: PMC8532357 DOI: 10.1186/s12934-021-01694-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 10/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Metabolomics coupled with genome-scale metabolic modeling approaches have been employed recently to quantitatively analyze the physiological states of various organisms, including Saccharomyces cerevisiae. Although yeast physiology in laboratory strains is well-studied, the metabolic states under industrially relevant scenarios such as winemaking are still not sufficiently understood, especially as there is considerable variation in metabolism between commercial strains. To study the potential causes of strain-dependent variation in the production of volatile compounds during enological conditions, random flux sampling and statistical methods were used, along with experimental extracellular metabolite flux data to characterize the differences in predicted intracellular metabolic states between strains. RESULTS It was observed that four selected commercial wine yeast strains (Elixir, Opale, R2, and Uvaferm) produced variable amounts of key volatile organic compounds (VOCs). Principal component analysis was performed on extracellular metabolite data from the strains at three time points of cell cultivation (24, 58, and 144 h). Separation of the strains was observed at all three time points. Furthermore, Uvaferm at 24 h, for instance, was most associated with propanol and ethyl hexanoate. R2 was found to be associated with ethyl acetate and Opale could be associated with isobutanol while Elixir was most associated with phenylethanol and phenylethyl acetate. Constraint-based modeling (CBM) was employed using the latest genome-scale metabolic model of yeast (Yeast8) and random flux sampling was performed with experimentally derived fluxes at various stages of growth as constraints for the model. The flux sampling simulations allowed us to characterize intracellular metabolic flux states and illustrate the key parts of metabolism that likely determine the observed strain differences. Flux sampling determined that Uvaferm and Elixir are similar while R2 and Opale exhibited the highest degree of differences in the Ehrlich pathway and carbon metabolism, thereby causing strain-specific variation in VOC production. The model predictions also established the top 20 fluxes that relate to phenotypic strain variation (e.g. at 24 h). These fluxes indicated that Opale had a higher median flux for pyruvate decarboxylase reactions compared with the other strains. Conversely, R2 which was lower in all VOCs, had higher median fluxes going toward central metabolism. For Elixir and Uvaferm, the differences in metabolism were most evident in fluxes pertaining to transaminase and hexokinase associated reactions. The applied analysis of metabolic divergence unveiled strain-specific differences in yeast metabolism linked to fusel alcohol and ester production. CONCLUSIONS Overall, this approach proved useful in elucidating key reactions in amino acid, carbon, and glycerophospholipid metabolism which suggest genetic divergence in activity in metabolic subsystems among these wine strains related to the observed differences in VOC formation. The findings in this study could steer more focused research endeavors in developing or selecting optimal aroma-producing yeast stains for winemaking and other types of alcoholic fermentations.
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Affiliation(s)
- William T Scott
- Department of Chemical Engineering, University of California, Davis, CA, USA.,Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Eddy J Smid
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - David E Block
- Department of Chemical Engineering, University of California, Davis, CA, USA.,Department of Viticulture and Enology, University of California, Davis, CA, USA
| | - Richard A Notebaart
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands.
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Scott WT, van Mastrigt O, Block DE, Notebaart RA, Smid EJ. Nitrogenous Compound Utilization and Production of Volatile Organic Compounds among Commercial Wine Yeasts Highlight Strain-Specific Metabolic Diversity. Microbiol Spectr 2021; 9:e0048521. [PMID: 34287034 PMCID: PMC8562342 DOI: 10.1128/spectrum.00485-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 06/14/2021] [Indexed: 11/20/2022] Open
Abstract
Genetic background and environmental conditions affect the production of sensory impact compounds by Saccharomyces cerevisiae. The relative importance of the strain-specific metabolic capabilities for the production of volatile organic compounds (VOCs) remains unclear. We investigated which amino acids contribute to VOC production and whether amino acid-VOC relations are conserved among yeast strains. Amino acid consumption and production of VOCs during grape juice fermentation was investigated using four commercial wine yeast strains: Elixir, Opale, R2, and Uvaferm. Principal component analysis of the VOC data demonstrated that Uvaferm correlated with ethyl acetate and ethyl hexanoate production, R2 negatively correlated with the acetate esters, and Opale positively correlated with fusel alcohols. Biomass formation was similar for all strains, pointing to metabolic differences in the utilization of nutrients to form VOCs. Partial least-squares linear regression showed that total aroma production is a function of nitrogen utilization (R2 = 0.87). We found that glycine, tyrosine, leucine, and lysine utilization were positively correlated with fusel alcohols and acetate esters. Mechanistic modeling of the yeast metabolic network via parsimonious flux balance analysis and flux enrichment analysis revealed enzymes with crucial roles, such as transaminases and decarboxylases. Our work provides insights in VOC production in wine yeasts. IMPORTANCE Saccharomyces cerevisiae is widely used in grape juice fermentation to produce wines. Along with the genetic background, the nitrogen in the environment in which S. cerevisiae grows impacts its regulation of metabolism. Also, commercial S. cerevisiae strains exhibit immense diversity in their formation of aromas, and a desirable aroma bouquet is an essential characteristic for wines. Since nitrogen affects aroma formation in wines, it is essential to know the extent of this connection and how it leads to strain-dependent aroma profiles in wines. We evaluated the differences in the production of key aroma compounds among four commercial wine strains. Moreover, we analyzed the role of nitrogen utilization on the formation of various aroma compounds. This work illustrates the unique aroma-producing differences among industrial yeast strains and suggests more intricate, nitrogen-associated routes influencing those aroma-producing differences.
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Affiliation(s)
- William T. Scott
- Department of Chemical Engineering, University of California, Davis, California, USA
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Oscar van Mastrigt
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - David E. Block
- Department of Chemical Engineering, University of California, Davis, California, USA
- Department of Viticulture and Enology, University of California, Davis, California, USA
| | - Richard A. Notebaart
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Eddy J. Smid
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
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Contribution of Grape Skins and Yeast Choice on the Aroma Profiles of Wines Produced from Pinot Noir and Synthetic Grape Musts. FERMENTATION 2021. [DOI: 10.3390/fermentation7030168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The aroma profile is a key component of Pinot noir wine quality, and this is influenced by the diversity, quantity, and typicity of volatile compounds present. Volatile concentrations are largely determined by the grape itself and by microbial communities that produce volatiles during fermentation, either from grape-derived precursors or as byproducts of secondary metabolism. The relative degree of aroma production from grape skins compared to the juice itself, and the impact on different yeasts on this production, has not been investigated for Pinot noir. The influence of fermentation media (Pinot noir juice or synthetic grape must (SGM), with and without inclusion of grape skins) and yeast choice (commercial Saccharomyces cerevisiae EC1118, a single vineyard mixed community (MSPC), or uninoculated) on aroma chemistry was determined by measuring 39 volatiles in finished wines using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS). Fermentation medium clearly differentiated the volatile profile of wines with and without yeast, while differences between EC1118 and MSPC wines were only distinct for Pinot noir juice without skins. SGM with skins produced a similar aroma profile to Pinot noir with skins, suggesting that grape skins, and not the pulp, largely determine the aroma of Pinot noir wines.
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Xiang X, Su C, Shi Q, Wu J, Zeng Z, Zhang L, Jin S, Huang R, Gao T, Song C. Potential hypoglycemic metabolites in dark tea fermented by Eurotium cristatum based on UPLC-QTOF-MS/MS combining global metabolomic and spectrum-effect relationship analyses. Food Funct 2021; 12:7546-7556. [PMID: 34227645 DOI: 10.1039/d1fo00836f] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The preventive and therapeutic effects of dark tea fermented by Eurotium cristatum (DTE) in glucose metabolism have been demonstrated. However, few studies have investigated comprehensive changes in the chemical composition and activity in DTE before and after fermentation. In this study, the metabolic profiling of raw samples and fermented samples was determined by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). Furthermore, a systematic analytical strategy combining global metabolomics and the spectrum-effect relationship based on α-glucosidase inhibition was employed for screening discriminant metabolites. As a result, 15 discriminant metabolites were identified in DTE samples. Among them, 10 metabolites (4 fatty acids, 1 dyphylline derivative, 3 lysophosphatidylcholines, and 2 triterpenes) increased in relative contents and the contents of the other 5 polyphenol metabolites decreased after fermentation. These metabolites were critical constituents possibly associated with DTE's hypoglycemic activity, which also might be suitable as quality evaluation indicators. This study provided a worthy insight into the exploration of representative active constituents or quality indicators of DTE.
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Affiliation(s)
- Xingliang Xiang
- College of Pharmacy, Hubei University of Chinese Medicine, 16 Huangjiahu West Road, Hongshan District, 430065, Wuhan, Hubei, China.
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Industrially Applicable De Novo Lager Yeast Hybrids with a Unique Genomic Architecture: Creation and Characterization. Appl Environ Microbiol 2021; 87:AEM.02434-20. [PMID: 33188002 PMCID: PMC7848916 DOI: 10.1128/aem.02434-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 11/07/2020] [Indexed: 12/30/2022] Open
Abstract
All lager beer is produced using two related lager yeast types: group I and group II, which are highly similar, resulting in a lack of strain diversity for lager beer production. To date, approaches for generating new lager yeasts have generated strains possessing undesirable brewing characteristics which render them commercially inviable. Lager beer is produced by Saccharomyces pastorianus, which is a natural allopolyploid hybrid between Saccharomyces cerevisiae and Saccharomyces eubayanus. Lager strains are classified into two major groups based largely on genomic composition: group I and group II. Group I strains are allotriploid, whereas group II strains are allotetraploid. A lack of phenotypic diversity in commercial lager strains has led to substantial interest in the reconstitution of de novo allotetraploid lager strains by hybridization of S. cerevisiae and S. eubayanus strains. Such strategies rely on the hybridization of wild S. eubayanus isolates, which carry unacceptable traits for commercial lager beer such as phenolic off flavors and incomplete utilization of carbohydrates. Using an alternative breeding strategy, we have created de novo lager hybrids containing the domesticated S. eubayanus subgenome from an industrial S. pastorianus strain by hybridizing diploid meiotic segregants of this strain to a variety of S. cerevisiae ale strains. Five de novo hybrids were isolated which had fermentation characteristics similar to those of prototypical commercial lager strains but with unique phenotypic variation due to the contributions of the S. cerevisiae parents. Genomic analysis of these de novo lager hybrids identified novel allotetraploid genomes carrying three copies of the S. cerevisiae genome and one copy of the S. eubayanus genome. Most importantly, these hybrids do not possess the negative traits which result from breeding wild S. eubayanus. The de novo lager strains produced using industrial S. pastorianus in this study are immediately suitable for industrial lager beer production. IMPORTANCE All lager beer is produced using two related lager yeast types: group I and group II, which are highly similar, resulting in a lack of strain diversity for lager beer production. To date, approaches for generating new lager yeasts have generated strains possessing undesirable brewing characteristics which render them commercially inviable. We have used an alternative approach that circumvents this issue and created new lager strains that are directly suitable for lager beer production. These novel lager strains also possess a unique genomic architecture, which may lead to a better understanding of industrial yeast hybrids. We propose that strains created using our approach be classified as a third group of lager strains (group III). We anticipate that these novel lager strains will be of great industrial relevance and that this technique will be applicable to the creation of additional novel lager strains that will help broaden the diversity in commercial lager beer strains.
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Li X, Cen N, Liu L, Chen Y, Yang X, Yu K, Guo J, Liao X, Shi B. Collagen Peptide Provides Saccharomyces cerevisiae with Robust Stress Tolerance for Enhanced Bioethanol Production. ACS APPLIED MATERIALS & INTERFACES 2020; 12:53879-53890. [PMID: 33211491 DOI: 10.1021/acsami.0c18919] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Efficient production of bioethanol is desirable for bioenergy large-scale applications, but it is severely challenged by ethanol and sugar stresses. Here, collagen peptide (CP), as a renewable nitrogen-containing biomass, remarkably enhanced the stress resistance of Saccharomyces cerevisiae SLL-510 against ethanol challenge, based on its unique amino acid composition. Transcriptome analysis showed that the energy, lipid, cofactor, and vitamin metabolism may involve in stress tolerance provided by CP. When CP was added into the media containing 249.99 mg/mL glucose, the bioethanol yield increased from 8.03 to 12.25% (v/v) and 11.35 to 12.29% (v/v) at 43 and 120 h, respectively. Moreover, at 286.79 mg/mL glucose, the highest yield reached 14.48% (v/v), with 99.58% glucose utilization rate. The protection and promotion effects of CP were also shown by four other industrial S. cerevisiae strains. These results coupled with the advantages of abundant reserves, cleanliness, and renewability revealed that CP is a promising economically viable and industrially scalable enhancer for bioethanol fermentation.
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Affiliation(s)
- Xia Li
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Nengkai Cen
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Lu Liu
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Yongle Chen
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Xi Yang
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Kang Yu
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Junling Guo
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
| | - Xuepin Liao
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
- The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, PR China
| | - Bi Shi
- Department of Biomass and Leather Engineering, Sichuan University, Chengdu 610065, PR China
- The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University, Chengdu 610065, PR China
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Walker GA, Henderson CM, Luong P, Block DE, Bisson LF. Downshifting Yeast Dominance: Cell Physiology and Phospholipid Composition Are Altered With Establishment of the [ GAR +] Prion in Saccharomyces cerevisiae. Front Microbiol 2020; 11:2011. [PMID: 32983023 PMCID: PMC7477300 DOI: 10.3389/fmicb.2020.02011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/29/2020] [Indexed: 11/13/2022] Open
Abstract
Establishment of the [GAR +] prion in Saccharomyces cerevisiae reduces both transcriptional expression of the HXT3 hexose transporter gene and fermentation capacity in high sugar conditions. We evaluated the impact of deletion of the HXT3 gene on the expression of [GAR +] prion phenotype in a vineyard isolate, UCD932, and found that changes in fermentation capacity were observable even with complete loss of the Hxt3 transporter, suggesting other cellular functions affecting fermentation rate may be impacted in [GAR +] strains. In a comparison of isogenic [GAR +] and [gar -] strains, localization of the Pma1 plasma membrane ATPase showed differences in distribution within the membrane. In addition, plasma membrane lipid composition varied between the two cell types. Oxygen uptake was decreased in prion induced cells suggesting membrane changes affect plasma membrane functionality beyond glucose transport. Thus, multiple cell surface properties are altered upon induction of the [GAR +] prion in addition to changes in expression of the HXT3 gene. We propose a model wherein [GAR +] prion establishment within a yeast population is associated with modulation of plasma membrane functionality, fermentation capacity, niche dominance, and cell physiology to facilitate growth and mitigate cytotoxicity under certain environmental conditions. Down-regulation of expression of the HXT3 hexose transporter gene is only one component of a suite of physiological differences. Our data show the [GAR +] prion state is accompanied by multiple changes in the yeast cell surface that prioritize population survivability over maximizing metabolic capacity and enable progeny to establish an alternative adaptive state while maintaining reversibility.
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Affiliation(s)
- Gordon A Walker
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Clark M Henderson
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Peter Luong
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - David E Block
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
| | - Linda F Bisson
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, United States
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15
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Gibson B, Dahabieh M, Krogerus K, Jouhten P, Magalhães F, Pereira R, Siewers V, Vidgren V. Adaptive Laboratory Evolution of Ale and Lager Yeasts for Improved Brewing Efficiency and Beer Quality. Annu Rev Food Sci Technol 2020; 11:23-44. [DOI: 10.1146/annurev-food-032519-051715] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Yeasts directly impact the efficiency of brewery fermentations as well as the character of the beers produced. In recent years, there has been renewed interest in yeast selection and development inspired by the demand to utilize resources more efficiently and the need to differentiate beers in a competitive market. Reviewed here are the different, non-genetically modified (GM) approaches that have been considered, including bioprospecting, hybridization, and adaptive laboratory evolution (ALE). Particular emphasis is placed on the latter, which represents an extension of the processes that have led to the domestication of strains already used in commercial breweries. ALE can be used to accentuate the positive traits of brewing yeast as well as temper some of the traits that are less desirable from a modern brewer's perspective. This method has the added advantage of being non-GM and therefore suitable for food and beverage production.
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Affiliation(s)
- B. Gibson
- VTT Technical Research Centre of Finland Ltd, FI-02044 Espoo, Finland
| | - M. Dahabieh
- Renaissance BioScience, Vancouver, British Columbia, Canada, V6T1Z3
| | - K. Krogerus
- VTT Technical Research Centre of Finland Ltd, FI-02044 Espoo, Finland
| | - P. Jouhten
- VTT Technical Research Centre of Finland Ltd, FI-02044 Espoo, Finland
| | - F. Magalhães
- VTT Technical Research Centre of Finland Ltd, FI-02044 Espoo, Finland
| | - R. Pereira
- Division of Systems and Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - V. Siewers
- Division of Systems and Synthetic Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - V. Vidgren
- VTT Technical Research Centre of Finland Ltd, FI-02044 Espoo, Finland
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16
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Susceptibility of biomembrane structure towards amphiphiles, ionic liquids, and deep eutectic solvents. ADVANCES IN BIOMEMBRANES AND LIPID SELF-ASSEMBLY 2020. [DOI: 10.1016/bs.abl.2020.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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17
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Tesnière C. Importance and role of lipids in wine yeast fermentation. Appl Microbiol Biotechnol 2019; 103:8293-8300. [PMID: 31402425 DOI: 10.1007/s00253-019-10029-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/09/2019] [Accepted: 07/12/2019] [Indexed: 01/14/2023]
Abstract
This review summarizes the current knowledge on the importance and role of lipids in wine yeast fermentation. Lipids play an important role in membrane structure, adaptation to stress, or as signaling molecules. They are also essential nutrients whose availability can vary depending on winemaking technology, with major effects on yeast alcoholic fermentation. Moreover, lipid supplementation can greatly stimulate the formation of yeast volatile metabolites.
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Affiliation(s)
- Catherine Tesnière
- UMR SPO, INRA, Montpellier SupAgro, Université de Montpellier, Montpellier, France.
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18
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Pre-fermentative supplementation of fatty acids alters the metabolic activity of wine yeasts. Food Res Int 2019; 121:835-844. [PMID: 31108815 DOI: 10.1016/j.foodres.2019.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 12/15/2022]
Abstract
Fatty acids play important roles in the maintenance of cell membrane, viability and overall metabolism of wine yeasts (particularly Saccharomyces cerevisiae) during adverse winemaking conditions. We previously showed that linoleic acid supplementation markedly affect aroma compound production of S. cerevisiae wine strains. However, very little is known about how other commonly found fatty acids in grape juice modulate the growth and metabolism of S. cerevisiae. We aimed to determine the individual effect of five fatty acids on fermentation patterns and metabolism of two wine yeast strains (S. cerevisiae EC1118 and X5). Microvinification was performed at 15 °C by supplementing a grape juice (individually) with three different concentrations of saturated (palmitic acid), unsaturated (oleic, linoleic and γ-linolenic acids) and short-chain (hexanoic acid) fatty acids. Metabolite profiles of the resulting wines were determined using Gas-chromatography coupled to Mass-spectrometry (GC-MS). Our data show that the addition of γ-linolenic acid to the juice caused the production of higher amounts of amino and organic acids (except isoleucine and 2-oxoglutaric acid) in wines when fermented by EC1118, while palmitic acid supplementation showed similar trends when fermented by X5. The effect of linoleic acid was independent of yeast strains and we observed a global reduction of amino and organic acids (except pyruvic acid) while increased production of most of the fatty acids other than the supplemented ones. Our data clearly suggest that pre-fermentative supplementation of different fatty acids indeed influenced the growth and metabolism of wine yeasts in a different way. Thus, attention needs to be paid not only to the wine yeast strain used during the winemaking but also to the overall grape juice composition, including fatty acids, to obtain the desired wine characteristics.
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Genotype-by-Environment-by-Environment Interactions in the Saccharomyces cerevisiae Transcriptomic Response to Alcohols and Anaerobiosis. G3-GENES GENOMES GENETICS 2018; 8:3881-3890. [PMID: 30301737 PMCID: PMC6288825 DOI: 10.1534/g3.118.200677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Next generation biofuels including longer-chain alcohols such as butanol are attractive as renewable, high-energy fuels. A barrier to microbial production of butanols is the increased toxicity compared to ethanol; however, the cellular targets and microbial defense mechanisms remain poorly understood, especially under anaerobic conditions used frequently in industry. Here we took a comparative approach to understand the response of Saccharomyces cerevisiae to 1-butanol, isobutanol, or ethanol, across three genetic backgrounds of varying tolerance in aerobic and anaerobic conditions. We find that strains have different growth properties and alcohol tolerances with and without oxygen availability, as well as unique and common responses to each of the three alcohols. Our results provide evidence for strain-by-alcohol-by-oxygen interactions that moderate how cells respond to alcohol stress.
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20
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Lipidomics Studies on Mitochondrial Damage of Saccharomyces cerevisiae Induced by Heavy Ion Beam Radiation. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2018. [DOI: 10.1016/s1872-2040(18)61123-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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21
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Chou HC, Šuklje K, Antalick G, Schmidtke LM, Blackman JW. Late-Season Shiraz Berry Dehydration That Alters Composition and Sensory Traits of Wine. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:7750-7757. [PMID: 29962206 DOI: 10.1021/acs.jafc.8b01646] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Late-season berry dehydration (LSD) is a common occurrence in Shiraz grapes, particularly those grown in hot climates. LSD results in significant yield reductions; however, the effects on wine composition and sensory characteristics are not well-documented. Wines made of 100% nonshriveled clusters (control) were related to red fruit flavors by the sensory panel, whereas wines made of 80% shriveled clusters (S-VCT) were perceived as more alcoholic and associated with dark fruit and dead/stewed fruit characters. The latter wines also resulted in higher concentrations of massoia lactone and γ-nonalactone, compounds known to contribute to prune and stewed-fruit aromas. Wines made of shriveled grapes were also characterized by an increase in C6-alcohols and a decrease in esters, whereas wine terpenoids were altered compound-specific. An increase in orange pigments and wine chemical age in S-VCT wines indicated faster oxidative aging compared to the control. LSD appeared to alter final wine composition directly but also appeared to influence yeast metabolism, potentially due to an alteration of the composition of lipids in the grape juice. This study emphasized the relevance of sorting shriveled and nonshriveled berries for final wine chemical composition and wine style.
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Affiliation(s)
| | | | | | - Leigh M Schmidtke
- The Australian Research Council Training Centre for Innovative Wine Production , The University of Adelaide , Glen Osmond , South Australia 5064 , Australia
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22
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du Plessis M, Franken J, Bauer FF. Carnitine Requires Choline to Exert Physiological Effects in Saccharomyces cerevisiae. Front Microbiol 2018; 9:1362. [PMID: 30034373 PMCID: PMC6043790 DOI: 10.3389/fmicb.2018.01362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/05/2018] [Indexed: 11/25/2022] Open
Abstract
L-Carnitine is a key metabolite in the energy metabolism of eukaryotic cells, functioning as a shuttling molecule for activated acyl-residues between cellular compartments. In higher eukaryotes this function is essential, and defects in carnitine metabolism has severe effects on fatty acid and carbon metabolism. Carnitine supplementation has been associated with an array of mostly beneficial impacts in higher eukaryotic cells, including stress protection and regulation of redox metabolism in diseased cells. Some of these phenotypes have no obvious link to the carnitine shuttle, and suggest that carnitine has as yet unknown shuttle-independent functions. The existence of shuttle-independent functions has also been suggested in Saccharomyces cerevisiae, including a beneficial effect during hydrogen peroxide stress and a detrimental impact when carnitine is co-supplemented with the reducing agent dithiothreitol (DTT). Here we used these two distinct yeast phenotypes to screen for potential genetic factors that suppress the shuttle independent physiological effects of carnitine. Two deletion strains, Δcho2 and Δopi3, coding for enzymes that catalyze the sequential conversion of phosphatidylethanolamine to phosphatidylcholine were identified for suppressing the phenotypic effects of carnitine. Additional characterisation indicated that the suppression cannot be explained by differences in phospholipid homeostasis. The phenotypes could be reinstated by addition of extracellular choline, but show that the requirement for choline is not based on some overlapping function or the structural similarities of the two molecules. This is the first study to suggest a molecular link between a specific metabolite and carnitine-dependent, but shuttle-independent phenotypes in eukaryotes.
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Affiliation(s)
| | | | - Florian F. Bauer
- Department of Viticulture and Oenology, Institute for Wine Biotechnology, Stellenbosch University, Stellenbosch, South Africa
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23
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Hafenstine GR, Harris AW, Ma K, Cha JN, Goodwin AP. Conversion of Ethanol to 2-Ethylhexenal at Ambient Conditions Using Tandem, Biphasic Catalysis. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2017; 5:10483-10489. [PMID: 33224638 PMCID: PMC7678241 DOI: 10.1021/acssuschemeng.7b02487] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Ethanol is a ubiquitous fermentation product well-tolerated by microbes, but purification from growth media requires multiple distillations or other energy intensive processes. Converting such metabolites to larger, hydrophobic products would both yield higher energy products and facilitate separation. Here, we demonstrate the conversion of C2 ethanol to C8 2-ethylhexenal via a sequential oxidation-aldol-hydrogenation-aldol process with solar energy as the only required input. Photocatalysis was utilized to drive enzymatic oxidation of ethanol, while biphasic media in conjunction with aldol coupling and Pd assisted hydrogenation kept the oxidation and reduction processes physically and chemically separated. Using this process, 2-ethylhexenal was produced from ethanol in both buffer and diluted yeast media.
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Affiliation(s)
- Glenn R. Hafenstine
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
| | - Alexander W. Harris
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
| | - Ke Ma
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
| | - Jennifer N. Cha
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
- Materials Science and Engineering Program, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
| | - Andrew P. Goodwin
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
- Materials Science and Engineering Program, University of Colorado Boulder, 3145 Colorado Avenue, 596 UCB, Boulder, Colorado 80303, United States
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Qiu Z, Jiang R. Improving Saccharomyces cerevisiae ethanol production and tolerance via RNA polymerase II subunit Rpb7. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:125. [PMID: 28515784 PMCID: PMC5433082 DOI: 10.1186/s13068-017-0806-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 04/27/2017] [Indexed: 05/31/2023]
Abstract
BACKGROUND Classical strain engineering methods often have limitations in altering multigenetic cellular phenotypes. Here we try to improve Saccharomyces cerevisiae ethanol tolerance and productivity by reprogramming its transcription profile through rewiring its key transcription component RNA polymerase II (RNAP II), which plays a central role in synthesizing mRNAs. This is the first report on using directed evolution method to engineer RNAP II to alter S. cerevisiae strain phenotypes. RESULTS Error-prone PCR was employed to engineer the subunit Rpb7 of RNAP II to improve yeast ethanol tolerance and production. Based on previous studies and the presumption that improved ethanol resistance would lead to enhanced ethanol production, we first isolated variant M1 with much improved resistance towards 8 and 10% ethanol. The ethanol titers of M1 was ~122 g/L (96.58% of the theoretical yield) under laboratory very high gravity (VHG) fermentation, 40% increase as compared to the control. DNA microarray assay showed that 369 genes had differential expression in M1 after 12 h VHG fermentation, which are involved in glycolysis, alcoholic fermentation, oxidative stress response, etc. CONCLUSIONS This is the first study to demonstrate the possibility of engineering eukaryotic RNAP to alter global transcription profile and improve strain phenotypes. Targeting subunit Rpb7 of RNAP II was able to bring differential expression in hundreds of genes in S. cerevisiae, which finally led to improvement in yeast ethanol tolerance and production.
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Affiliation(s)
- Zilong Qiu
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459 Singapore
| | - Rongrong Jiang
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459 Singapore
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25
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Krogerus K, Seppänen-Laakso T, Castillo S, Gibson B. Inheritance of brewing-relevant phenotypes in constructed Saccharomyces cerevisiae × Saccharomyces eubayanus hybrids. Microb Cell Fact 2017; 16:66. [PMID: 28431563 PMCID: PMC5399851 DOI: 10.1186/s12934-017-0679-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/09/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Interspecific hybridization has proven to be a potentially valuable technique for generating de novo lager yeast strains that possess diverse and improved traits compared to their parent strains. To further enhance the value of hybridization for strain development, it would be desirable to combine phenotypic traits from more than two parent strains, as well as remove unwanted traits from hybrids. One such trait, that has limited the industrial use of de novo lager yeast hybrids, is their inherent tendency to produce phenolic off-flavours; an undesirable trait inherited from the Saccharomyces eubayanus parent. Trait removal and the addition of traits from a third strain could be achieved through sporulation and meiotic recombination or further mating. However, interspecies hybrids tend to be sterile, which impedes this opportunity. RESULTS Here we generated a set of five hybrids from three different parent strains, two of which contained DNA from all three parent strains. These hybrids were constructed with fertile allotetraploid intermediates, which were capable of efficient sporulation. We used these eight brewing strains to examine two brewing-relevant phenotypes: stress tolerance and phenolic off-flavour formation. Lipidomics and multivariate analysis revealed links between several lipid species and the ability to ferment in low temperatures and high ethanol concentrations. Unsaturated fatty acids, such as oleic acid, and ergosterol were shown to positively influence growth at high ethanol concentrations. The ability to produce phenolic off-flavours was also successfully removed from one of the hybrids, Hybrid T2, through meiotic segregation. The potential application of these strains in industrial fermentations was demonstrated in wort fermentations, which revealed that the meiotic segregant Hybrid T2 not only didn't produce any phenolic off-flavours, but also reached the highest ethanol concentration and consumed the most maltotriose. CONCLUSIONS Our study demonstrates the possibility of constructing complex yeast hybrids that possess traits that are relevant to industrial lager beer fermentation and that are derived from several parent strains. Yeast lipid composition was also shown to have a central role in determining ethanol and cold tolerance in brewing strains.
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Affiliation(s)
- Kristoffer Krogerus
- VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, 02044 Espoo, Finland
- Department of Biotechnology and Chemical Technology, Aalto University, School of Chemical Technology, Kemistintie 1, Aalto, P.O. Box 16100, 00076 Espoo, Finland
| | | | - Sandra Castillo
- VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, 02044 Espoo, Finland
| | - Brian Gibson
- VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, 02044 Espoo, Finland
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26
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García-Ríos E, Morard M, Parts L, Liti G, Guillamón JM. The genetic architecture of low-temperature adaptation in the wine yeast Saccharomyces cerevisiae. BMC Genomics 2017; 18:159. [PMID: 28196526 PMCID: PMC5310122 DOI: 10.1186/s12864-017-3572-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 02/09/2017] [Indexed: 12/25/2022] Open
Abstract
Background Low-temperature growth and fermentation of wine yeast can enhance wine aroma and make them highly desirable traits for the industry. Elucidating response to cold in Saccharomyces cerevisiae is, therefore, of paramount importance to select or genetically improve new wine strains. As most enological traits of industrial importance in yeasts, adaptation to low temperature is a polygenic trait regulated by many interacting loci. Results In order to unravel the genetic determinants of low-temperature fermentation, we mapped quantitative trait loci (QTLs) by bulk segregant analyses in the F13 offspring of two Saccharomyces cerevisiae industrial strains with divergent performance at low temperature. We detected four genomic regions involved in the adaptation at low temperature, three of them located in the subtelomeric regions (chromosomes XIII, XV and XVI) and one in the chromosome XIV. The QTL analysis revealed that subtelomeric regions play a key role in defining individual variation, which emphasizes the importance of these regions’ adaptive nature. Conclusions The reciprocal hemizygosity analysis (RHA), run to validate the genes involved in low-temperature fermentation, showed that genetic variation in mitochondrial proteins, maintenance of correct asymmetry and distribution of phospholipid in the plasma membrane are key determinants of low-temperature adaptation. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3572-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Estéfani García-Ríos
- Departamento de Biotecnología de los alimentos, Instituto de Agroquímica y Tecnología de los Alimentos (CSIC), Avda. Agustín Escardino, 7, E-46980-Paterna, Valencia, Spain
| | - Miguel Morard
- Departamento de Biotecnología de los alimentos, Instituto de Agroquímica y Tecnología de los Alimentos (CSIC), Avda. Agustín Escardino, 7, E-46980-Paterna, Valencia, Spain.,Departament de Genètica, Facultat de Ciències Biològiques, Universitat de València, Dr. Moliner, 50, E-46100 Burjassot, València, Spain
| | - Leopold Parts
- European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg, 69117, Germany.,Wellcome Trust Sanger Institute, Hinxton, CB101SA, UK
| | - Gianni Liti
- Institute of Research on Cancer and Ageing of Nice (IRCAN), CNRS UMR 7284-INSERM U1081, Faculté de Médecine, Université de Nice Sophia Antipolis, Nice, France
| | - José M Guillamón
- Departamento de Biotecnología de los alimentos, Instituto de Agroquímica y Tecnología de los Alimentos (CSIC), Avda. Agustín Escardino, 7, E-46980-Paterna, Valencia, Spain.
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27
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Jain S, Dholakia H, Kirtley W, Oelkers P. Energy Storage in Yeast: Regulation and Competition with Ethanol Production. Curr Microbiol 2016; 73:851-858. [PMID: 27620384 DOI: 10.1007/s00284-016-1127-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/18/2016] [Indexed: 10/21/2022]
Abstract
Mechanisms that may regulate the storage of energy as triacylglycerol in Saccharomyces cerevisiae were examined. First, the kinetics of Dga1p, which mediates the majority of diacylglycerol esterification, the lone committed step in triacylglycerol synthesis, was measured in vitro. With an apparent K m of 17.0 μM, Dga1p has higher affinity for oleoyl-CoA than the only S. cerevisiae acyltransferase previously kinetically characterized, Lpt1p. Lpt1p is a 1-acylglycerol-3-phosphate O-acyltransferase that produces phosphatidate, a precursor to diacylglycerol. Therefore, limiting triacylglycerol synthesis to situations of elevated acyl-CoA concentration is unlikely. However, Dga1p's apparent V max of 5.8 nmol/min/mg was 20 times lower than Lpt1p's. This supports Dga1p being rate limiting for TAG synthesis. Dga1p activity was not activated or inhibited when seven different molecules (e.g., ATP) which reflect cellular energy status were provided at physiological concentrations. Thus, allosteric regulation was not found. Coordination between triacylglycerol and glycogen synthesis was also tested. Yeast genetically deficient in triacylglycerol synthesis did not store more energy in glycogen and vice versa. Lastly, we tested whether genetically limiting energy storage in triacylglycerol, glycogen, steryl esters, or combinations of these will increase ethanol production efficiency. In nutrient-rich media containing 5 % glucose, solely limiting glycogen synthesis had the greatest affect, increasing ethanol production efficiency by 12 %. Since limiting glycogen synthesis only had a modest effect on growth in media containing 10 % ethanol, such genetic manipulation may improve commercial ethanol production.
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Affiliation(s)
- Shilpa Jain
- Department of Bioscience and Biotechnology, Drexel University, 3245 Chestnut Street, Philadelphia, PA, 19104, USA.,Trac Services Ltd, Trevenson Road, TR153, Truro, Cornwall, UK
| | - Hemal Dholakia
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA
| | - Winston Kirtley
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA
| | - Peter Oelkers
- Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, MI, 48128, USA.
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28
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Ofosu Appiah C, Zakpaa HD, Mak Mensah E, Bentil JA. Evaluation of ethanol production from pito mash using Zymomonas mobilis and Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2016. [DOI: 10.5897/ajb2015.15042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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29
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Evidence for a Role for the Plasma Membrane in the Nanomechanical Properties of the Cell Wall as Revealed by an Atomic Force Microscopy Study of the Response of Saccharomyces cerevisiae to Ethanol Stress. Appl Environ Microbiol 2016; 82:4789-4801. [PMID: 27235439 DOI: 10.1128/aem.01213-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/23/2016] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED A wealth of biochemical and molecular data have been reported regarding ethanol toxicity in the yeast Saccharomyces cerevisiae However, direct physical data on the effects of ethanol stress on yeast cells are almost nonexistent. This lack of information can now be addressed by using atomic force microscopy (AFM) technology. In this report, we show that the stiffness of glucose-grown yeast cells challenged with 9% (vol/vol) ethanol for 5 h was dramatically reduced, as shown by a 5-fold drop of Young's modulus. Quite unexpectedly, a mutant deficient in the Msn2/Msn4 transcription factor, which is known to mediate the ethanol stress response, exhibited a low level of stiffness similar to that of ethanol-treated wild-type cells. Reciprocally, the stiffness of yeast cells overexpressing MSN2 was about 35% higher than that of the wild type but was nevertheless reduced 3- to 4-fold upon exposure to ethanol. Based on these and other data presented herein, we postulated that the effect of ethanol on cell stiffness may not be mediated through Msn2/Msn4, even though this transcription factor appears to be a determinant in the nanomechanical properties of the cell wall. On the other hand, we found that as with ethanol, the treatment of yeast with the antifungal amphotericin B caused a significant reduction of cell wall stiffness. Since both this drug and ethanol are known to alter, albeit by different means, the fluidity and structure of the plasma membrane, these data led to the proposition that the cell membrane contributes to the biophysical properties of yeast cells. IMPORTANCE Ethanol is the main product of yeast fermentation but is also a toxic compound for this process. Understanding the mechanism of this toxicity is of great importance for industrial applications. While most research has focused on genomic studies of ethanol tolerance, we investigated the effects of ethanol at the biophysical level and found that ethanol causes a strong reduction of the cell wall rigidity (or stiffness). We ascribed this effect to the action of ethanol perturbing the cell membrane integrity and hence proposed that the cell membrane contributes to the cell wall nanomechanical properties.
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30
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Sugar and Glycerol Transport in Saccharomyces cerevisiae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 892:125-168. [PMID: 26721273 DOI: 10.1007/978-3-319-25304-6_6] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In Saccharomyces cerevisiae the process of transport of sugar substrates into the cell comprises a complex network of transporters and interacting regulatory mechanisms. Members of the large family of hexose (HXT) transporters display uptake efficiencies consistent with their environmental expression and play physiological roles in addition to feeding the glycolytic pathway. Multiple glucose-inducing and glucose-independent mechanisms serve to regulate expression of the sugar transporters in yeast assuring that expression levels and transporter activity are coordinated with cellular metabolism and energy needs. The expression of sugar transport activity is modulated by other nutritional and environmental factors that may override glucose-generated signals. Transporter expression and activity is regulated transcriptionally, post-transcriptionally and post-translationally. Recent studies have expanded upon this suite of regulatory mechanisms to include transcriptional expression fine tuning mediated by antisense RNA and prion-based regulation of transcription. Much remains to be learned about cell biology from the continued analysis of this dynamic process of substrate acquisition.
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31
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Improving conversion yield of fermentable sugars into fuel ethanol in 1st generation yeast-based production processes. Curr Opin Biotechnol 2015; 33:81-6. [DOI: 10.1016/j.copbio.2014.12.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/08/2014] [Accepted: 12/14/2014] [Indexed: 11/22/2022]
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32
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Yeast toxicogenomics: lessons from a eukaryotic cell model and cell factory. Curr Opin Biotechnol 2015; 33:183-91. [DOI: 10.1016/j.copbio.2015.03.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 02/16/2015] [Accepted: 03/05/2015] [Indexed: 12/21/2022]
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33
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Correlation between ethanol stress and cellular fatty acid composition of alcohol producing non-Saccharomyces in comparison with Saccharomyces cerevisiae by multivariate techniques. Journal of Food Science and Technology 2015; 52:6770-6. [PMID: 26396428 DOI: 10.1007/s13197-015-1762-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 01/14/2015] [Accepted: 02/02/2015] [Indexed: 10/24/2022]
Abstract
Wine production is a complex process both from biochemical and microbiological point of view in which yeast plays a central role. The use of the wine yeast Saccharomyces cerevisiae and non- Saccharomyces yeasts as mixed starter cultures for wine fermentations is of increasing interest to enhance the quality of wine.The most common stress, yeast cells encounter during wine fermentation is the increase in ethanol concentration.To enhance ethanol tolerance, alteration in the cellular lipid composition is one of its defence mechanism. Ethanol tolerance and cellular fatty acid composition of alcohol producing non Saccharomyces forms were compared with enological strains of Sacccharomyces cerevisiae. Saccharomyces cerevisiae used for the study, tolerated 15 % of ethanol and the non Saccharomyces strains such as, Issatchenkia occidentalis and Issatchenkia orientalis tolerated 10 % of ethanol. On exposure of Saccharomyces cerevisiae to ethanol stress, the proportion of monounsaturated fatty acids increased with concomitant decrease in saturated fatty acids. Decrease in monounsaturated fatty acids, exhibited by non-Saccharomyces yeasts when exposed to ethanol stress, could be one of the reasons for their inability to withstand more than 10 % of alcohol. Multivariate techniques of data analysis - principal component analysis and linear discriminant analysis were employed in order to establish differentiation criteria as function of yeast strains, alcohol stress and their fatty acid profile. Based on the data, Chemometrics, such as principal component analysis and discriminant function analysis, can be successfully applied to fatty acid data to categorize the yeast.
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34
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New lager yeast strains generated by interspecific hybridization. J Ind Microbiol Biotechnol 2015; 42:769-78. [PMID: 25682107 PMCID: PMC4412690 DOI: 10.1007/s10295-015-1597-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/30/2015] [Indexed: 12/24/2022]
Abstract
The interspecific hybrid Saccharomyces pastorianus is the most commonly used yeast in brewery fermentations worldwide. Here, we generated de novo lager yeast hybrids by mating a domesticated and strongly flocculent Saccharomyces cerevisiae ale strain with the Saccharomyces eubayanus type strain. The hybrids were characterized with respect to the parent strains in a wort fermentation performed at temperatures typical for lager brewing (12 °C). The resulting beers were analysed for sugar and aroma compounds, while the yeasts were tested for their flocculation ability and α-glucoside transport capability. These hybrids inherited beneficial properties from both parent strains (cryotolerance, maltotriose utilization and strong flocculation) and showed apparent hybrid vigour, fermenting faster and producing beer with higher alcohol content (5.6 vs 4.5 % ABV) than the parents. Results suggest that interspecific hybridization is suitable for production of novel non-GM lager yeast strains with unique properties and will help in elucidating the evolutionary history of industrial lager yeast.
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35
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Sitepu IR, Garay LA, Sestric R, Levin D, Block DE, German JB, Boundy-Mills KL. Oleaginous yeasts for biodiesel: Current and future trends in biology and production. Biotechnol Adv 2014; 32:1336-1360. [DOI: 10.1016/j.biotechadv.2014.08.003] [Citation(s) in RCA: 251] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 07/25/2014] [Accepted: 08/18/2014] [Indexed: 10/24/2022]
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36
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Examining the role of membrane lipid composition in determining the ethanol tolerance of Saccharomyces cerevisiae. Appl Environ Microbiol 2014; 80:2966-72. [PMID: 24610851 DOI: 10.1128/aem.04151-13] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Yeast (Saccharomyces cerevisiae) has an innate ability to withstand high levels of ethanol that would prove lethal to or severely impair the physiology of other organisms. Significant efforts have been undertaken to elucidate the biochemical and biophysical mechanisms of how ethanol interacts with lipid bilayers and cellular membranes. This research has implicated the yeast cellular membrane as the primary target of the toxic effects of ethanol. Analysis of model membrane systems exposed to ethanol has demonstrated ethanol's perturbing effect on lipid bilayers, and altering the lipid composition of these model bilayers can mitigate the effect of ethanol. In addition, cell membrane composition has been correlated with the ethanol tolerance of yeast cells. However, the physical phenomena behind this correlation are likely to be complex. Previous work based on often divergent experimental conditions and time-consuming low-resolution methodologies that limit large-scale analysis of yeast fermentations has fallen short of revealing shared mechanisms of alcohol tolerance in Saccharomyces cerevisiae. Lipidomics, a modern mass spectrometry-based approach to analyze the complex physiological regulation of lipid composition in yeast and other organisms, has helped to uncover potential mechanisms for alcohol tolerance in yeast. Recent experimental work utilizing lipidomics methodologies has provided a more detailed molecular picture of the relationship between lipid composition and ethanol tolerance. While it has become clear that the yeast cell membrane composition affects its ability to tolerate ethanol, the molecular mechanisms of yeast alcohol tolerance remain to be elucidated.
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37
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Zingaro KA, Nicolaou SA, Papoutsakis ET. Dissecting the assays to assess microbial tolerance to toxic chemicals in bioprocessing. Trends Biotechnol 2013; 31:643-53. [DOI: 10.1016/j.tibtech.2013.08.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/14/2013] [Accepted: 08/19/2013] [Indexed: 11/15/2022]
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38
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Gibson BR, Storgårds E, Krogerus K, Vidgren V. Comparative physiology and fermentation performance of Saaz and Frohberg lager yeast strains and the parental species Saccharomyces eubayanus. Yeast 2013; 30:255-66. [PMID: 23695993 DOI: 10.1002/yea.2960] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/03/2013] [Accepted: 05/07/2013] [Indexed: 01/30/2023] Open
Abstract
Two distinct genetic groups (Saaz and Frohberg) exist within the hybrid Saccharomyces pastorianus (S. cerevisiae × S. eubayanus) taxon. However, physiological/technological differences that exist between the two groups are not known. Fermentative capability of the parental S. eubayanus has likewise never been studied. Here, 58 lager strains were screened to determine which hybrid group they belonged to, and selected strains were characterized to determine salient characteristics. In 15 °P all-malt wort fermentations at 22 °C, Frohberg strains showed greater growth and superior fermentation (80% apparent attenuation, 6.5% alcohol by volume in 3-4 days) compared to all other strains and maintained highest viability values (>93%). Fermentation with S. eubayanus was poor at the same temperature (33% apparent attenuation, 2.7% alcohol by volume at 6 days and viability reduced to 75%). Saaz strains and S. eubayanus were the least sensitive to cold (10 °C), though this did not translate to greater fermentation performance. Fermentation with S. eubayanus was poor at 10 °C but equal to or greater than that of the Saaz strains. Performance of Saaz yeast/S. eubayanus was limited by an inability to use wort maltotriose. [(14)C]-Maltotriose transport assays also showed negligible activity in these strains (≤0.5 µmol min(-1) g(-1) dry yeast). Beers from Saaz fermentations were characterized by two- to sixfold lower production of the flavour compounds methyl butanol, ethyl acetate and 3-methylbutyl acetate compared to Frohberg strains. Higher alcohol and ester production by S. eubayanus was similar to that of Frohberg strains.
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Affiliation(s)
- Brian R Gibson
- VTT Technical Research Centre of Finland, FI-02044 VTT, Finland.
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39
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Fermentation temperature modulates phosphatidylethanolamine and phosphatidylinositol levels in the cell membrane of Saccharomyces cerevisiae. Appl Environ Microbiol 2013; 79:5345-56. [PMID: 23811519 DOI: 10.1128/aem.01144-13] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
During alcoholic fermentation, Saccharomyces cerevisiae is 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 three Saccharomyces cerevisiae strains 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 fermenting S. cerevisiae modulates its membrane lipid composition in a temperature-dependent manner.
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