| 1. |
- Bettiga, Maurizio, 1978, et al.
(författare)
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Robust S. cerevisiae strain for next generation bio-processes: concepts and case-studies
- 2013
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Ingår i: Cell Factories and Biosustainability (Hilleroed, Denmark, May 5-8 2013).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The realization of an oil independent economy relies on the development of competitive processes for the production of fuels and chemicals from renewable resources. The extensive research on second-generation ethanol has paved the way to a new concept of bio-based industry, where lignocellulosic material is the primary source of sugars, to be converted to a number of fuels and chemicals. Harsh conditions during the bioconversion of lignocellulose-derived sugars to the desired products drastically hamper cell viability and therefore productivity. Microbial inhibition limits bioprocesses to an extent such that it can be said that understanding and harnessing microbial robustness is a prerequisite for the feasibility of new bioprocess and the production of renewable fuels and chemicals.Current research carried out by our group focuses on the yeast Saccharomyces cerevisiae and aims at investigating the molecular bases of microbial robustness. Our efforts include the identification of the molecular targets of different classes of fermentation inhibitors aiming at understanding the complex responses of the cells to these compounds. The final goal is to engineer more robust strains. The concept of robustness will be discussed and examples of key features for S. cerevisiae robustness as well as examples of successful engineering to increase robustness will be presented.
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| 2. |
- Bettiga, Maurizio, 1978, et al.
(författare)
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Robust S. cerevisiae strain for next generation bio-processes: concepts and case-studies
- 2013
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Ingår i: 35th Symposium on Biotechnology for Fuels and Chemicals (Portland, OR. April 29-May 2, 2013).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The realization of an oil independent economy relies on the development of competitive processes for the production of fuels and chemicals from renewable resources. The extensive research on second-generation ethanol has paved the way to a new concept of bio-based industry, where lignocellulosic material is the primary source of sugars, to be converted to a number of fuels and chemicals. Sugars are released from cellulose and hemicellulose by pretreatment and hydrolysis steps. Harsh conditions result in the formation of a number of compounds, originating from sugars and lignin breakdown and acting as microorganism inhibitors. Weak organic acids, furaldehydes and phenolic compounds are sources of stress for the fermenting microorganism, as they influence cellular metabolism in a number of ways, including direct damage on cellular functions or by perturbations of the cellular energy and redox metabolism. In addition, the product of interest can act as a potent inhibitor. Regardless of the product, robust microorganisms are a prerequisite for the feasibility of lignocellulose-based bioprocesses.Current research carried out by our group focuses on the yeast Saccharomyces cerevisiae and aims at investigating the molecular bases of microbial robustness. Our efforts include the identification of the molecular targets of different classes of fermentation inhibitors aiming at understanding the complex responses of the cells to these compounds. The final goal is to engineer more robust strains. The concept of robustness will be discussed and examples of key features for S. cerevisiae robustness as well as examples of successful engineering to increase robustness will be presented.
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| 3. |
- Bettiga, Maurizio, 1978, et al.
(författare)
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Robust yeast strains as prerequisite for feasible biofuels production from renewable biomass resources
- 2013
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Ingår i: FEMS-V congress of European Microbiologists.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The extensive research on second-generation ethanol has paved the way to a new concept of industry, where lignocellulosic material is the primary source of sugars for the bio-based production of a number of fuels and chemicals. The technological achievements in biomass pretreatment and hydrolysis allow today to efficiently obtain sugars from cellulose and hemicellulose. However, a number of unwanted compounds, acting as microorganism inhibitors, are released from sugars and lignin breakdown as well. In addition, the product of interest can act as a potent inhibitor. Regardless of the product, robust microorganisms are a prerequisite for the feasibility of lignocellulose-based bioprocesses.Current research carried out by our group aims at investigating the molecular bases of microbial robustness, with a major focus on the yeast Saccharomyces cerevisiae. The molecular targets of different classes of fermentation inhibitors can be identified and used as cues for new strategies to engineer more robust strains. During the presentation, the concept of robustness will be discussed and examples of key features for S. cerevisiae robustness will be presented.
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| 4. |
- Bettiga, Maurizio, 1978, et al.
(författare)
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Yeast physiology studies and metabolic engineering for enhanced robustness
- 2014
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Ingår i: Enzitec 2014- XI Seminário Brasileiro de Tecnologia Enzimática. Barra da Tijuca-Rio de Janeiro, April 14th to 16th, 2014.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The extensive research on second-generation ethanol has paved the way to a new concept of bio-based industry, where lignocellulosic material is the primary source of sugars, to be converted to a number of fuels and chemicals. Sugars are released from cellulose and hemicellulose by pretreatment and hydrolysis steps. Harsh conditions during pretreatment promote the formation of a number of inhibitory compounds, among which weak organic acids, furaldehydes and phenolic compounds. In addition, the product of interest can act as a potent inhibitor. Regardless of the product, robust microorganisms are a prerequisite for the feasibility of lignocellulose-based bioprocesses.Current research carried out by our group focuses on the yeast Saccharomyces cerevisiae and aims at investigating the molecular bases of microbial robustness. Our efforts include the identification of the molecular targets of different classes of fermentation inhibitors aiming at understanding the complex responses of the cells to these compounds. The final goal is to engineer more robust strains. The concept of robustness will be discussed and examples of key features for S. cerevisiae robustness as well as examples of successful engineering to increase robustness will be presented.In particular, during this presentation, the following results will be discussed i) the study of redox and energy metabolism as key determinants of tolerance; ii) conversion routes of in S. cerevisiae as a way of detoxification from phenolic compounds; iii) cell membrane engineering as a strategy to achieve enhanced tolerance to weak acids.
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| 5. |
- Lindberg, Lina, 1984, et al.
(författare)
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Comparative lipidomic profiling of Saccharomyces cerevisiae to reveal lipid composition changes in the plasma membrane upon exposure to lignocellulose inhibitors
- 2012
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Ingår i: 2nd Eur. Symp. on Microbial Lipids: Diversity in Structure and Function, Bern, Switzerland, 16. - 19. May 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During pretreatment of lignocellulose raw material, compounds that severely inhibit microbial activity including Saccharomyces cerevisiae strains are released [1]. These compounds, which include furaldehydes and weak organic acids, inhibit yeast metabolism and affect yeast viability and, as a consequence, reduces the overallproductivity of an ethanol production process [2].Elucidation of the molecular mechanisms behind inhibition can suggest new strategies to prevent the inhibitory effect. In the present study, the possible effect on the plasma membrane in S. cerevisiae is studied as a response to inhibitors present in lignocellulose raw material.A comparative lipidomic profiling will be carried out on S. cerevisiae cultured in the absence and presence of lignocellulose inhibitors. LC-CAD and GC-MS will be used toextensively characterize the composition of the plasma membrane. Changes in membrane composition will be correlated with the presence of specific inhibitors.References1. Palmqvist E, Hahn-Hägerdal B: Fermentation of lignocellulosic hydrolysates. II: Inhibitorsand mechanisms of inhibition. Bioresource Technology 2000, 74(1):25-33.2. Klinke HB, Thomsen AB, Ahring BK: Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. AppliedMicrobiology and Biotechnology 2004, 66(1):10-26
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| 6. |
- Lindberg, Lina, 1984, et al.
(författare)
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Fundamental studies reveal membrane engineering as strain engineering target for enhanced robustness towards lignocellulose hydrolysate inhibitors.
- 2014
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Ingår i: 36th Symposium on Biotechnology for Fuels and Chemicals, April 2-May 1st, Clearwater Beach, Florids, USA.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Bio-processes for the production of fuels and chemicals will contribute to the so-called bioeconomy, where biomass will represent an important source of hydrocarbons. A new concept of bio-based industry is now under development, where lignocellulosic material is the primary source of sugars to be converted in a biorefinery concept not to ethanol or fuels only, but to a portfolio of chemicals. Regardless of the product, robust microorganisms are a prerequisite for the feasibility of lignocellulose bioconversion.Current research carried out by our group focuses on the yeast Saccharomyces cerevisiae and aims at investigating the molecular bases of microbial robustness. The goal is to identify successful strain engineering strategies to confer yeast higher robustness. Zygosaccharomyces bailii is a yeast specie that tolerates low pH and high concentrations of weak organic acids. Thus, in order to elucidate a possible link between lipid composition and acetic acid tolerance, a comparative lipidomic profiling of the major lipid species found in the plasma membrane of S. cerevisiae and Z. bailii was performed. The study revealed remarkable changes in glycerolphospholipids and sphingolipids pools in Z. bailii compared to S. cerevisiae, suggesting lipid saturation, high sphingolipid levels as possible determinants of acetic acid tolerance.
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| 7. |
- Lindberg, Lina, 1984, et al.
(författare)
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Investigation of weak organic acid tolerance mechanisms by lipidomic profiling of Saccharomyces cerevisiae and Zygosaccaromyces bailii
- 2012
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Ingår i: Life Science Engineering Area of Advance Conference. From Human health to Biosustainability – Future challenges for Life Science at Chalmers.Gothenburg, Sweden.November 19, 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During pretreatment of lignocellulose raw material, compounds such as furaldehydes, phenolics and weak organic acids, severely inhibiting Saccharomyces cerevisiae, are released. Decrease of intracellular pH after diffusion through the plasma membrane is thought to be one of the effects mediating the cellular toxicity of weak organic acids.The aim of the present study is to investigate the relationship between plasma membrane composition and acid tolerance, in order to develop a strategy for engineering a S. cerevisiae strain more tolerant to acetic acid. Zygosaccharomyces bailii, a well-known food spoilage yeast, is highly tolerant to acetic acid and will be used as a model for weak organic acid tolerance.A complete lipidomic profiling of S. cerevisiae and Z. bailii in the presence and absence of acetic acid will be carried out using LC-MS/MS. Similarities and differences in the two profiles will be correlated with acid tolerance.
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| 8. |
- Lindberg, Lina, 1984, et al.
(författare)
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Lipidomic Profiling of Saccharomyces cerevisiae and Zygosaccharomyces bailii Reveals Critical Changes in Lipid Composition in Response to Acetic Acid Stress
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 8:9
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Tidskriftsartikel (refereegranskat)abstract
- When using microorganisms as cell factories in the production of bio-based fuels or chemicals from lignocellulosic hydrolysate, inhibitory concentrations of acetic acid, released from the biomass, reduce the production rate. The undissociated form of acetic acid enters the cell by passive diffusion across the lipid bilayer, mediating toxic effects inside the cell. In order to elucidate a possible link between lipid composition and acetic acid stress, the present study presents detailed lipidomic profiling of the major lipid species found in the plasma membrane, including glycerophospholipids, sphingolipids and sterols, in Saccharomyces cerevisiae (CEN.PK 113_7D) and Zygosaccharomyces bailii (CBS7555) cultured with acetic acid. Detailed physiological characterization of the response of the two yeasts to acetic acid has also been performed in aerobic batch cultivations using bioreactors. Physiological characterization revealed, as expected, that Z. bailii is more tolerant to acetic acid than S. cerevisiae. Z. bailii grew at acetic acid concentrations above 24 g L−1, while limited growth of S. cerevisiae was observed after 11 h when cultured with only 12 g L−1 acetic acid. Detailed lipidomic profiling using electrospray ionization, multiple-reaction-monitoring mass spectrometry (ESI-MRM-MS) showed remarkable changes in the glycerophospholipid composition of Z. bailii, including an increase in saturated glycerophospholipids and considerable increases in complex sphingolipids in both S. cerevisiae (IPC 6.2×, MIPC 9.1×, M(IP)2C 2.2×) and Z. bailii (IPC 4.9×, MIPC 2.7×, M(IP)2C 2.7×), when cultured with acetic acid. In addition, the basal level of complex sphingolipids was significantly higher in Z. bailii than in S. cerevisiae, further emphasizing the proposed link between lipid saturation, high sphingolipid levels and acetic acid tolerance. The results also suggest that acetic acid tolerance is associated with the ability of a given strain to generate large rearrangements in its lipid profile.
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| 9. |
- Lindberg, Lina, 1984, et al.
(författare)
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Molecular mechanisms behind acetic acid resistance: Insights from Zygosaccharomyces bailii
- 2013
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Ingår i: 5th Conference on Physiology of Yeast and Filamentous Fungi (PYFF).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Biomass derived products will play a significant role in the development towards a sustainable society. The feasibility of the production of bio-based chemicals relies on robust industrial microorganisms. One major issue reducing process productivity is the high concentration of acetic acid, released during pretreatment of lignocellulose raw material. Acetic acid effect on yeast has been widely investigated: reduced intracellular pH [1], accumulation of the acetate anion [2], and signaling effects triggering cell death [3] are some of the mechanisms indicated as responsible for its toxicity. Zygosaccharomyces bailii is a yeast species that tolerates low pH and high concentrations of weak organic acids [4]. It is a common food spoilage yeast, typically isolated from acetic acid rich environments such as vinegar or pickles. Z. bailii is extensively investigated from a food science perspective, for the development of food preservatives. Its potential for industrial applications as a model organism for acetic acid resistance has been less investigated. Its tolerance has been explained to some extent by retained intracellular pH and plasma membrane integrity [5,6], specific acetate transporter supporting growth on acetate even in the presence of glucose [7], and higher metabolic flux through the unique ZbACS2 acetyl-CoA syntethase [8]. In the present study, the metabolic response of Z.bailii (CBS 7555) to acetic acid was characterized in a comparative investigation together with Saccharomyces cerevisiae (CEN.PK.0113_7D). Fermentation results indicate that S. cerevisiae tolerates significantly lower acetic acid concentrations compared to Z. bailii. Acetic acid affected S. cerevisiae mainly by decreasing maximum specific growth rate and specific substrate consumption rate. Z. bailii on the other hand was mainly affected by an increased lag phase. Z. bailii displayed sustained growth at acetic acid concentrations as high as 36 g/L, while concentrations above 9 g/L severely decreased the maximum specific growth rate of S. cerevisiae. The molecular mechanisms behind acetic acid resistance in Z. bailii are currently being investigated in order to formulate strategies to improve acetic acid tolerance in S. cerevisiae.References[1] Casal et al. FEMS Microbiol Rev (2008) 32(6): 974[2] Russel. J. Appl Bacteriol (1992) 73: 363[3] Ludovico et al. Microbiology (2001) 147:2409[4] Fleet G. Crit. Rev. Biotechnol (1992) 12: 1[5] Arneborg et al. Arch Microbiol (2000) 174:125[6] Prudenico et al. Cytometry (1998) 31:307[7] Sousa et al. Appl. Environ. Microbiol. (1996) 62:3152[8] Rodrigues et al. PLOSone (2012) 7(12): e52402
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| 10. |
- Lindberg, Lina, 1984, et al.
(författare)
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Sphingolipids: A potential key to acetic acid resistance in Zygosaccharomyces bailii
- 2013
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Ingår i: Biomembranes: Molecular Architecture, Dynamics and Function, Joint FEBS – EMBO Advanced Lecture Course.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Biomass derived products will play a significant role in the development towards a sustainable society. One major issue in the production of bio-based chemicals, using microorganisms as cell-factories, is the high and therefore inhibitory concentration of acetic acid, released during pretreatment of lignocellulose raw material. Acetic acid toxicity in Saccharomyces cerevisiae has been explained by reduced intracellular pH [1], accumulation of the acetate anion [2], and signaling effects triggering cell death [3]. The undissociated form of acetic acid enters the cell by passive diffusion over the lipid bilayer, although recent publications also suggest the involvement of Fps1p, aquaglyceroporin channel in the acetate uptake [4].The aim of the present study is to investigate the potential relationship between plasma membrane lipid composition and acetic acid resistance, in the two yeasts S. cerevisiae and Zygosaccharomyces bailii. Z. bailii is a common food spoilage yeast, typically isolated from acetic acid rich environments such as vinegar or pickles and is used in this study as a model for acetic acid resistance. Previous publications demonstrated that Z. bailii unlike S. cerevisiae exhibit retained intracellular pH [5] and plasma membrane integrity [6] upon exposure to acetic acid. Detailed lipidomic profiling of glycerophospholipids, sphingolipids and sterols using multiple-reaction-monitoring mass spectrometry (MRM-MS) has been performed with total lipids extracts from S. cerevisiae and Z. bailii cultured in the absence and presence of acetic acid. Lipidome analysis pointed out sphingolipids as a key mediator in acetic acid resistance with strong increase in both S. cerevisiae and Z. bailii, when cultured with acetic acid. First, the basal levels of complex sphingolipids were 13 times higher in Z. bailii, possibly explaining the higher acetic acid resistance of this yeast species in comparison to S. cerevisiae. Moreover Z. bailii showed an astounding ability to remodel its membrane composition upon acetic acid stress, with strong increase in complex sphingolipids and a drastic reduction of glycerophospholipids. The next step of this study will be to use the lipid data to develop a strategy to engineer the lipid metabolism of S. cerevisiae towards increased acetic acid resistance. [1] Casal et al. FEMS Microbiol Rev (2008) 32(6): 974; [2] Russel. J. Appl Bacteriol (1992) 73: 363, [3] Ludovico et al. Microbiology (2001) 147:2409, [4] Mollapour et al. Mol Cell Biol (2007) 27(18):6446, [5] Arneborg et al. Archives of Microbiology (2000) 174(1-2):125, [6] Prudêncio et al. Cytometry (1998) 31(4):307
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