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Topaloğlu A, Esen Ö, Turanlı-Yıldız B, Arslan M, Çakar ZP. From Saccharomyces cerevisiae to Ethanol: Unlocking the Power of Evolutionary Engineering in Metabolic Engineering Applications. J Fungi (Basel) 2023; 9:984. [PMID: 37888240 PMCID: PMC10607480 DOI: 10.3390/jof9100984] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/25/2023] [Accepted: 09/28/2023] [Indexed: 10/28/2023] Open
Abstract
Increased human population and the rapid decline of fossil fuels resulted in a global tendency to look for alternative fuel sources. Environmental concerns about fossil fuel combustion led to a sharp move towards renewable and environmentally friendly biofuels. Ethanol has been the primary fossil fuel alternative due to its low carbon emission rates, high octane content and comparatively facile microbial production processes. In parallel to the increased use of bioethanol in various fields such as transportation, heating and power generation, improvements in ethanol production processes turned out to be a global hot topic. Ethanol is by far the leading yeast output amongst a broad spectrum of bio-based industries. Thus, as a well-known platform microorganism and native ethanol producer, baker's yeast Saccharomyces cerevisiae has been the primary subject of interest for both academic and industrial perspectives in terms of enhanced ethanol production processes. Metabolic engineering strategies have been primarily adopted for direct manipulation of genes of interest responsible in mainstreams of ethanol metabolism. To overcome limitations of rational metabolic engineering, an alternative bottom-up strategy called inverse metabolic engineering has been widely used. In this context, evolutionary engineering, also known as adaptive laboratory evolution (ALE), which is based on random mutagenesis and systematic selection, is a powerful strategy to improve bioethanol production of S. cerevisiae. In this review, we focus on key examples of metabolic and evolutionary engineering for improved first- and second-generation S. cerevisiae bioethanol production processes. We delve into the current state of the field and show that metabolic and evolutionary engineering strategies are intertwined and many metabolically engineered strains for bioethanol production can be further improved by powerful evolutionary engineering strategies. We also discuss potential future directions that involve recent advancements in directed genome evolution, including CRISPR-Cas9 technology.
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Affiliation(s)
- Alican Topaloğlu
- Department of Molecular Biology and Genetics, Faculty of Science and Letters, Istanbul Technical University, Istanbul 34469, Türkiye; (A.T.); (Ö.E.)
- Dr. Orhan Öcalgiray Molecular Biology, Biotechnology and Genetics Research Center (ITU-MOBGAM), Istanbul Technical University, Istanbul 34469, Türkiye;
| | - Ömer Esen
- Department of Molecular Biology and Genetics, Faculty of Science and Letters, Istanbul Technical University, Istanbul 34469, Türkiye; (A.T.); (Ö.E.)
- Dr. Orhan Öcalgiray Molecular Biology, Biotechnology and Genetics Research Center (ITU-MOBGAM), Istanbul Technical University, Istanbul 34469, Türkiye;
| | - Burcu Turanlı-Yıldız
- Dr. Orhan Öcalgiray Molecular Biology, Biotechnology and Genetics Research Center (ITU-MOBGAM), Istanbul Technical University, Istanbul 34469, Türkiye;
| | - Mevlüt Arslan
- Department of Genetics, Faculty of Veterinary Medicine, Van Yüzüncü Yıl University, Van 65000, Türkiye;
| | - Zeynep Petek Çakar
- Department of Molecular Biology and Genetics, Faculty of Science and Letters, Istanbul Technical University, Istanbul 34469, Türkiye; (A.T.); (Ö.E.)
- Dr. Orhan Öcalgiray Molecular Biology, Biotechnology and Genetics Research Center (ITU-MOBGAM), Istanbul Technical University, Istanbul 34469, Türkiye;
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Jamaluddin, Riyanti EI, Mubarik NR, Listanto E. Construction of Novel Yeast Strains from Candida tropicalis KBKTI 10.5.1 and Saccharomyces cerevisiae DBY1 to Improve the Performance of Ethanol Production Using Lignocellulosic Hydrolysate. Trop Life Sci Res 2023; 34:81-107. [PMID: 38144374 PMCID: PMC10735269 DOI: 10.21315/tlsr2023.34.2.5] [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: 05/09/2022] [Accepted: 09/19/2022] [Indexed: 12/26/2023] Open
Abstract
Increased consumption of xylose-glucose and yeast tolerance to lignocellulosic hydrolysate are the keys to the success of second-generation bioethanol production. Candida tropicalis KBKTI 10.5.1 is a new isolated strain that has the ability to ferment xylose. In contrast to Saccharomyces cerevisiae DBY1 which only can produce ethanol from glucose fermentation. The research objective is the application of the genome shuffling method to increase the performance of ethanol production using lignocellulosic hydrolysate. Mutants were selected on xylose and glucose substrates separately and using random amplified polymorphic DNA (RAPD) analysis. The ethanol production using lignocellulosic hydrolysate by parents and mutants was evaluated using a batch fermentation system. Concentrations of ethanol, residual sugars, and by-products such as glycerol, lactate and acetate were measured using HPLC machine equipped with Hiplex H for carbohydrate column and a refraction index detector (RID). Ethanol produced by Fcs1 and Fcs4 mutants on acid hydrolysate increased by 26.58% and 24.17% from parent DBY1, by 14.94% and 21.84% from parent KBKTI 10.5.1. In contrast to the increase in ethanol production on alkaline hydrolysate, Fcs1 and Fcs4 mutants only experienced an increase in ethanol production by 1.35% from the parent KBKTI 10.5.1. Ethanol productivity by Fcs1 and Fcs4 mutants on acid hydrolysate reached 0.042 g/L/h and 0.044 g/L/h. The recombination of the genomes of different yeast species resulted in novel yeast strains that improved resistance performance and ethanol production on lignocellulosic hydrolysates.
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Affiliation(s)
- Jamaluddin
- Graduate School of IPB University, IPB University, Jl. Raya Dramaga, Kampus IPB Dramaga Bogor 16680 West Java, Indonesia
| | - Eny Ida Riyanti
- National Research and Innovation Agency (BRIN), Jl. Tentara Pelajar No 3A, Bogor 16111, Indonesia
| | - Nisa Rachmania Mubarik
- Department of Biology, Faculty of Mathematics and Natural Science, IPB University, Jl. Raya Dramaga, Kampus IPB Dramaga, Bogor 16680 West Java, Indonesia
| | - Edy Listanto
- National Research and Innovation Agency (BRIN), Jl. Tentara Pelajar No 3A, Bogor 16111, Indonesia
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Chatterjee S, Venkata Mohan S. Fungal biorefinery for sustainable resource recovery from waste. BIORESOURCE TECHNOLOGY 2022; 345:126443. [PMID: 34852279 DOI: 10.1016/j.biortech.2021.126443] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 11/21/2021] [Accepted: 11/24/2021] [Indexed: 06/13/2023]
Abstract
Depletion of natural resources and negative impact of fossil fuels on environment are becoming a global concern. The concept of biorefinery is one of the alternative platforms for the production of biofuels and chemicals. Valorisation of biological resources through complete utilization of waste, reusing secondary products and generating energy to power the process are the key principles of biorefinery. Agricultural residues and biogenic municipal solid wastes are getting importance as a potential feedstock for the generation of bioproducts. This communication reviews and highlights the scope of yeast and fungi as a potent candidate for the synthesis of gamut of bioproducts in an integrated approach addressing sustainability and circular bioeconomy. It also provides a close view on importance of microbes in biorefinery, feedstock pretreatment strategies for renewable sugar production, cultivation systems and yeast and fungi based products. Integrated closed loop approach towards multiple product generation with zero waste discharge is also discussed.
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Affiliation(s)
- Sulogna Chatterjee
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, 500007, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - S Venkata Mohan
- Bioengineering and Environmental Sciences Lab, Department of Energy and Environmental Engineering, CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, 500007, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, 201002, India.
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Li X, Wang Y, Li G, Liu Q, Pereira R, Chen Y, Nielsen J. Metabolic network remodelling enhances yeast’s fitness on xylose using aerobic glycolysis. Nat Catal 2021. [DOI: 10.1038/s41929-021-00670-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zan X, Sun J, Chu L, Cui F, Huo S, Song Y, Koffas MAG. Improved glucose and xylose co-utilization by overexpression of xylose isomerase and/or xylulokinase genes in oleaginous fungus Mucor circinelloides. Appl Microbiol Biotechnol 2021; 105:5565-5575. [PMID: 34215904 DOI: 10.1007/s00253-021-11392-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/28/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022]
Abstract
Most of the oleaginous microorganisms cannot assimilate xylose in the presence of glucose, which is the major bottleneck in the bioconversion of lignocellulose to biodiesel. Our present study revealed that overexpression of xylose isomerase (XI) gene xylA or xylulokinase (XK) gene xks1 increased the xylose consumption by 25 to 37% and enhanced the lipid content by 8 to 28% during co-fermentation of glucose and xylose. In xylA overexpressing strain Mc-XI, the activity of XI was 1.8-fold higher and the mRNA level of xylA at 24 h and 48 h was 11- and 13-fold higher than that of the control, respectively. In xks1 overexpressing strain Mc-XK, the mRNA level of xks1 was 4- to 11-fold of that of the control strain and the highest XK activity of 950 nmol min-1 mg-1 at 72 h which was 2-fold higher than that of the control. Additionally, expression of a translational fusion of xylA and xks1 further enhanced the xylose utilization rate by 45%. Our results indicated that overexpression of xylA and/or xks1 is a promising strategy to improve the xylose and glucose co-utilization, alleviate the glucose repression, and produce lipid from lignocellulosic biomass in the oleaginous fungus M. circinelloides. KEY POINTS: • Overexpressing xylA or xks1 increased the xylose consumption and the lipid content. • The xylose isomerase activity and the xylA mRNA level were enhanced in strain Mc-XI. • Co-expression of xylA and xks1 further enhanced the xylose utilization rate by 45%.
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Affiliation(s)
- Xinyi Zan
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Jianing Sun
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Linfang Chu
- School of Food Science and Technology, Jiang University, Wuxi, 214000, People's Republic of China
| | - Fengjie Cui
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Shuhao Huo
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China
| | - Yuanda Song
- Colin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, 255049, People's Republic of China.
| | - Mattheos A G Koffas
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
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A novel D-xylose isomerase from the gut of the wood feeding beetle Odontotaenius disjunctus efficiently expressed in Saccharomyces cerevisiae. Sci Rep 2021; 11:4766. [PMID: 33637780 PMCID: PMC7910561 DOI: 10.1038/s41598-021-83937-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/09/2021] [Indexed: 11/25/2022] Open
Abstract
Carbohydrate rich substrates such as lignocellulosic hydrolysates remain one of the primary sources of potentially renewable fuel and bulk chemicals. The pentose sugar d-xylose is often present in significant amounts along with hexoses. Saccharomyces cerevisiae can acquire the ability to metabolize d-xylose through expression of heterologous d-xylose isomerase (XI). This enzyme is notoriously difficult to express in S. cerevisiae and only fourteen XIs have been reported to be active so far. We cloned a new d-xylose isomerase derived from microorganisms in the gut of the wood-feeding beetle Odontotaenius disjunctus. Although somewhat homologous to the XI from Piromyces sp. E2, the new gene was identified as bacterial in origin and the host as a Parabacteroides sp. Expression of the new XI in S. cerevisiae resulted in faster aerobic growth than the XI from Piromyces on d-xylose media. The d-xylose isomerization rate conferred by the new XI was also 72% higher, while absolute xylitol production was identical in both strains. Interestingly, increasing concentrations of xylitol (up to 8 g L−1) appeared not to inhibit d-xylose consumption. The newly described XI displayed 2.6 times higher specific activity, 37% lower KM for d-xylose, and exhibited higher activity over a broader temperature range, retaining 51% of maximal activity at 30 °C compared with only 29% activity for the Piromyces XI.
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Crystal structure of a novel xylose isomerase from Streptomyces sp. F-1 revealed the presence of unique features that differ from conventional classes. Biochim Biophys Acta Gen Subj 2020; 1864:129549. [DOI: 10.1016/j.bbagen.2020.129549] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/24/2020] [Accepted: 02/04/2020] [Indexed: 01/12/2023]
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Nijland JG, Driessen AJM. Engineering of Pentose Transport in Saccharomyces cerevisiae for Biotechnological Applications. Front Bioeng Biotechnol 2020; 7:464. [PMID: 32064252 PMCID: PMC7000353 DOI: 10.3389/fbioe.2019.00464] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/19/2019] [Indexed: 01/05/2023] Open
Abstract
Lignocellulosic biomass yields after hydrolysis, besides the hexose D-glucose, D-xylose, and L-arabinose as main pentose sugars. In second generation bioethanol production utilizing the yeast Saccharomyces cerevisiae, it is critical that all three sugars are co-consumed to obtain an economically feasible and robust process. Since S. cerevisiae is unable to metabolize pentose sugars, metabolic pathway engineering has been employed to introduce the respective pathways for D-xylose and L-arabinose metabolism. However, S. cerevisiae lacks specific pentose transporters, and these sugars enter the cell with low affinity via glucose transporters of the Hxt family. Therefore, in the presence of D-glucose, utilization of D-xylose and L-arabinose is poor as the Hxt transporters prefer D-glucose. To solve this problem, heterologous expression of pentose transporters has been attempted but often with limited success due to poor expression and stability, and/or low turnover. A more successful approach is the engineering of the endogenous Hxt transporter family and evolutionary selection for D-glucose insensitive growth on pentose sugars. This has led to the identification of a critical and conserved asparagine residue in Hxt transporters that, when mutated, reduces the D-glucose affinity while leaving the D-xylose affinity mostly unaltered. Likewise, mutant Gal2 transporter have been selected supporting specific uptake of L-arabinose. In fermentation experiments, the transporter mutants support efficient uptake and consumption of pentose sugars, and even co-consumption of D-xylose and D-glucose when used at industrial concentrations. Further improvements are obtained by interfering with the post-translational inactivation of Hxt transporters at high or low D-glucose concentrations. Transporter engineering solved major limitations in pentose transport in yeast, now allowing for co-consumption of sugars that is limited only by the rates of primary metabolism. This paves the way for a more economical second-generation biofuels production process.
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Affiliation(s)
- Jeroen G Nijland
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology, University of Groningen, Groningen, Netherlands
| | - Arnold J M Driessen
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology, University of Groningen, Groningen, Netherlands
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Lee M, Rozeboom HJ, Keuning E, de Waal P, Janssen DB. Structure-based directed evolution improves S. cerevisiae growth on xylose by influencing in vivo enzyme performance. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:5. [PMID: 31938040 PMCID: PMC6954610 DOI: 10.1186/s13068-019-1643-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 12/22/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Efficient bioethanol production from hemicellulose feedstocks by Saccharomyces cerevisiae requires xylose utilization. Whereas S. cerevisiae does not metabolize xylose, engineered strains that express xylose isomerase can metabolize xylose by converting it to xylulose. For this, the type II xylose isomerase from Piromyces (PirXI) is used but the in vivo activity is rather low and very high levels of the enzyme are needed for xylose metabolism. In this study, we explore the use of protein engineering and in vivo selection to improve the performance of PirXI. Recently solved crystal structures were used to focus mutagenesis efforts. RESULTS We constructed focused mutant libraries of Piromyces xylose isomerase by substitution of second shell residues around the substrate- and metal-binding sites. Following library transfer to S. cerevisiae and selection for enhanced xylose-supported growth under aerobic and anaerobic conditions, two novel xylose isomerase mutants were obtained, which were purified and subjected to biochemical and structural analysis. Apart from a small difference in response to metal availability, neither the new mutants nor mutants described earlier showed significant changes in catalytic performance under various in vitro assay conditions. Yet, in vivo performance was clearly improved. The enzymes appeared to function suboptimally in vivo due to enzyme loading with calcium, which gives poor xylose conversion kinetics. The results show that better in vivo enzyme performance is poorly reflected in kinetic parameters for xylose isomerization determined in vitro with a single type of added metal. CONCLUSION This study shows that in vivo selection can identify xylose isomerase mutants with only minor changes in catalytic properties measured under standard conditions. Metal loading of xylose isomerase expressed in yeast is suboptimal and strongly influences kinetic properties. Metal uptake, distribution and binding to xylose isomerase are highly relevant for rapid xylose conversion and may be an important target for optimizing yeast xylose metabolism.
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Affiliation(s)
- Misun Lee
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Henriëtte J. Rozeboom
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Eline Keuning
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Paul de Waal
- DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands
| | - Dick B. Janssen
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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Zhu F, Deng H, He X, Song X, Chen N, Wang W. High-level expression of Thermobifida fusca glucose isomerase for high fructose corn syrup biosynthesis. Enzyme Microb Technol 2019; 135:109494. [PMID: 32146933 DOI: 10.1016/j.enzmictec.2019.109494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 01/02/2023]
Abstract
Glucose isomerase (GIase), an efficient enzyme in the isomerization of d-glucose to d-fructose, has been widely used in food processing. In this study, an efficient expression system for a Thermobifida fusca GIase (GIaseTfus) in Escherichia coli was firstly designed via a two-stage feeding strategy for improving expression level. The cultivation strategy was performed at an exponential feeding rate during the pre-induction phase, followed by a gradient-decreasing feeding rate at the induction phase in a 3-L fermenter. During this process, the effect of induction conditions and the complex nitrogen supplementation in feeding solutions on GIaseTfus production were investigated and optimized. Under the optimal conditions, the yield of GIaseTfus reached 124.1 U/mL, which is the highest expression level of GIase by recombinant E. coli reported to date. Additionally, the obtained GIaseTfus was performed to produce high fructose corn syrup (HFCS) with conversion approacing 55 % from glucose (45 %, w/v) to fructose. According to the molecular dynamic simulation, a number of hydrogen bonds existed in the enzyme-substrate complex could stablilize the transient states, and a appreciate reaction distance of M1 catalytic site and oxygen atom of glucose make the reaction proceed easily, thus resulting in the efficient biosynthesis of HFCS. The function of GIaseTfus renders it a valuable catalyst for HFCS-55 (containing 55 % d-fructose) manufacturing, the most favorable industrial product of HFCS. The efficient expression of GIaseTfus and its efficient HFCS production lays the foundation for its proming industrial application.
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Affiliation(s)
- Fucheng Zhu
- College of Biology and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, West Anhui University, Lu'an City 237012, China
| | - Hui Deng
- College of Biology and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, West Anhui University, Lu'an City 237012, China
| | - Xiaomei He
- College of Biology and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, West Anhui University, Lu'an City 237012, China
| | - Xiangwen Song
- College of Biology and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, West Anhui University, Lu'an City 237012, China
| | - Naifu Chen
- College of Biology and Pharmaceutical Engineering, Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources, West Anhui University, Lu'an City 237012, China.
| | - Weiyun Wang
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China.
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Seike T, Kobayashi Y, Sahara T, Ohgiya S, Kamagata Y, Fujimori KE. Molecular evolutionary engineering of xylose isomerase to improve its catalytic activity and performance of micro-aerobic glucose/xylose co-fermentation in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:139. [PMID: 31178927 PMCID: PMC6551904 DOI: 10.1186/s13068-019-1474-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/23/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Expression of d-xylose isomerase having high catalytic activity in Saccharomyces cerevisiae (S. cerevisiae) is a prerequisite for efficient and economical production of bioethanol from cellulosic biomass. Although previous studies demonstrated functional expression of several xylose isomerases (XI) in S. cerevisiae, identification of XIs having higher catalytic activity is needed. Here, we report a new strategy to improve xylose fermentation in the S. cerevisiae strain IR-2 that involves an evolutionary engineering to select top-performing XIs from eight previously reported XIs derived from various species. RESULTS Eight XI genes shown to have good expression in S. cerevisiae were introduced into the strain IR-2 having a deletion of GRE3 and XKS1 overexpression that allows use of d-xylose as a carbon source. Each transformant was evaluated under aerobic and micro-aerobic culture conditions. The strain expressing XI from Lachnoclostridium phytofermentans ISDg (LpXI) had the highest d-xylose consumption rate after 72 h of micro-aerobic fermentation on d-glucose and d-xylose mixed medium. To enhance LpXI catalytic activity, we performed random mutagenesis using error-prone polymerase chain reaction (PCR), which yielded two LpXI candidates, SS82 and SS92, that showed markedly improved fermentation performance. The LpXI genes in these clones carried either T63I or V162A/N303T point mutations. The SS120 strain expressing LpXI with the double mutation of T63I/V162A assimilated nearly 85 g/L d-glucose and 35 g/L d-xylose to produce 53.3 g/L ethanol in 72 h with an ethanol yield of approximately 0.44 (g/g-input sugars). An in vitro enzyme assay showed that, compared to wild-type, the LpXI double mutant in SS120 had a considerably higher V max (0.107 µmol/mg protein/min) and lower K m (37.1 mM). CONCLUSIONS This study demonstrated that LpXI has the highest d-xylose consumption rate among the XIs expressed in IR-2 under micro-aerobic co-fermentation conditions. A combination of novel mutations (T63I and V162A) significantly improved the enzymatic activity of LpXI, indicating that LpXI-T63I/V162A would be a potential construct for highly efficient production of cellulosic ethanol.
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Affiliation(s)
- Taisuke Seike
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 Japan
- Present Address: Center for Biosystems Dynamics Research (BDR), RIKEN, 6-2-3 Furuedai, Suita, Osaka 565-0874 Japan
| | - Yosuke Kobayashi
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 Japan
- Present Address: Biomaterial in Tokyo Company Limited, 4-7 Kashiwa-Inter-Minami, Kashiwa, Chiba 277-0872 Japan
| | - Takehiko Sahara
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 Japan
| | - Satoru Ohgiya
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-higashi, Toyohira, Sapporo, Hokkaido 062-8517 Japan
| | - Yoichi Kamagata
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 Japan
| | - Kazuhiro E. Fujimori
- Bioproduction Research Institute (BPRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566 Japan
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Understanding xylose isomerase from Burkholderia cenocepacia: insights into structure and functionality for ethanol production. AMB Express 2019; 9:73. [PMID: 31127459 PMCID: PMC6534634 DOI: 10.1186/s13568-019-0795-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/13/2019] [Indexed: 12/21/2022] Open
Abstract
The inability of the yeast Saccharomyces cerevisiae to produce ethanol from xylose has hampered the biofuel production from lignocellulosic biomass. However, prior studies reveal that functional expression of xylose isomerase (XI) from Burkholderia cenocepacia (XylABc) in S. cerevisiae has remarkably improved xylose consumption and ethanol productivity. Yet, little is known about kinetic and structural properties of this enzyme. Hereby, a purified recombinant XylA was assayed in vitro, showing optimal enzyme activity at 37 °C and pH 7.2. The Km of XylA for d-xylose was at least threefold lower than the Km results for any XI published to date (e.g. XylA from Piromyces sp.). In addition, oligomerization behavior as a tetramer was observed for XylA in solution. Functional and structural comparative analyses amongst three microbial XIs were further performed as theoretical models, showing that xylose orientation at the active site was highly conserved among the XIs. Mg2+ ions anchor the sugar and guide its pyranoside oxygen towards a histidine residue present at the active site, allowing an acid–base reaction, linearizing xylose. Electrostatic surface analyses showed that small variations in the net charge distribution and dipole moment could directly affect the way the substrate interacts with the protein, thus altering its kinetic properties. Accordingly, in silico modeling suggested the tetramer may be the major functional form. These analyses and the resulting model promote a better understanding of this protein family and pave the way to further protein engineering and application of XylA in the ethanol industry.
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Endalur Gopinarayanan V, Nair NU. Pentose Metabolism in Saccharomyces cerevisiae: The Need to Engineer Global Regulatory Systems. Biotechnol J 2019; 14:e1800364. [PMID: 30171750 PMCID: PMC6452637 DOI: 10.1002/biot.201800364] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/27/2018] [Indexed: 12/13/2022]
Abstract
Extending the host substrate range of industrially relevant microbes, such as Saccharomyces cerevisiae, has been a highly-active area of research since the conception of metabolic engineering. Yet, rational strategies that enable non-native substrate utilization in this yeast without the need for combinatorial and/or evolutionary techniques are underdeveloped. Herein, this review focuses on pentose metabolism in S. cerevisiae as a case study to highlight the challenges in this field. In the last three decades, work has focused on expressing exogenous pentose metabolizing enzymes as well as endogenous enzymes for effective pentose assimilation, growth, and biofuel production. The engineering strategies that are employed for pentose assimilation in this yeast are reviewed, and compared with metabolism and regulation of native sugar, galactose. In the case of galactose metabolism, multiple signals regulate and aid growth in the presence of the sugar. However, for pentoses that are non-native, it is unclear if similar growth and regulatory signals are activated. Such a comparative analysis aids in identifying missing links in xylose and arabinose utilization. While research on pentose metabolism have mostly concentrated on pathway level optimization, recent transcriptomics analyses highlight the need to consider more global regulatory, structural, and signaling components.
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Affiliation(s)
| | - Nikhil U Nair
- Department of Chemical and Biological Engineering, Tufts University, Medford, MA, 02155, U.S.A
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14
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Nosrati-Ghods N, Harrison STL, Isafiade AJ, Tai SL. Ethanol from Biomass Hydrolysates by Efficient Fermentation of Glucose and Xylose - A Review. CHEMBIOENG REVIEWS 2018. [DOI: 10.1002/cben.201800009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Nosaibeh Nosrati-Ghods
- University of Cape Town; Faculty of Engineering and the Built Environment; Department of Chemical Engineering; Private Bag 7701 Rondebosch South Africa
| | - Susan T. L. Harrison
- University of Cape Town; Faculty of Engineering and the Built Environment; Department of Chemical Engineering; Private Bag 7701 Rondebosch South Africa
| | - Adeniyi J. Isafiade
- University of Cape Town; Faculty of Engineering and the Built Environment; Department of Chemical Engineering; Private Bag 7701 Rondebosch South Africa
| | - Siew L. Tai
- University of Cape Town; Faculty of Engineering and the Built Environment; Department of Chemical Engineering; Private Bag 7701 Rondebosch South Africa
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15
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Lee M, Rozeboom HJ, de Waal PP, de Jong RM, Dudek HM, Janssen DB. Metal Dependence of the Xylose Isomerase from Piromyces sp. E2 Explored by Activity Profiling and Protein Crystallography. Biochemistry 2017; 56:5991-6005. [PMID: 29045784 PMCID: PMC5688467 DOI: 10.1021/acs.biochem.7b00777] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Xylose isomerase from Piromyces sp. E2 (PirXI) can be used to equip Saccharomyces cerevisiae with the capacity to ferment xylose to ethanol. The biochemical properties and structure of the enzyme have not been described even though its metal content, catalytic parameters, and expression level are critical for rapid xylose utilization. We have isolated the enzyme after high-level expression in Escherichia coli, analyzed the metal dependence of its catalytic properties, and determined 12 crystal structures in the presence of different metals, substrates, and substrate analogues. The activity assays revealed that various bivalent metals can activate PirXI for xylose isomerization. Among these metals, Mn2+ is the most favorable for catalytic activity. Furthermore, the enzyme shows the highest affinity for Mn2+, which was established by measuring the activation constants (Kact) for different metals. Metal analysis of the purified enzyme showed that in vivo the enzyme binds a mixture of metals that is determined by metal availability as well as affinity, indicating that the native metal composition can influence activity. The crystal structures show the presence of an active site similar to that of other xylose isomerases, with a d-xylose binding site containing two tryptophans and a catalytic histidine, as well as two metal binding sites that are formed by carboxylate groups of conserved aspartates and glutamates. The binding positions and conformations of the metal-coordinating residues varied slightly for different metals, which is hypothesized to contribute to the observed metal dependence of the isomerase activity.
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Affiliation(s)
- Misun Lee
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Henriëtte J Rozeboom
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Paul P de Waal
- DSM Biotechnology Center , Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands
| | - Rene M de Jong
- DSM Biotechnology Center , Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands
| | - Hanna M Dudek
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Dick B Janssen
- Biochemical Laboratory, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands
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16
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Temer B, dos Santos LV, Negri VA, Galhardo JP, Magalhães PHM, José J, Marschalk C, Corrêa TLR, Carazzolle MF, Pereira GAG. Conversion of an inactive xylose isomerase into a functional enzyme by co-expression of GroEL-GroES chaperonins in Saccharomyces cerevisiae. BMC Biotechnol 2017; 17:71. [PMID: 28888227 PMCID: PMC5591498 DOI: 10.1186/s12896-017-0389-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 08/18/2017] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Second-generation ethanol production is a clean bioenergy source with potential to mitigate fossil fuel emissions. The engineering of Saccharomyces cerevisiae for xylose utilization is an essential step towards the production of this biofuel. Though xylose isomerase (XI) is the key enzyme for xylose conversion, almost half of the XI genes are not functional when expressed in S. cerevisiae. To date, protein misfolding is the most plausible hypothesis to explain this phenomenon. RESULTS This study demonstrated that XI from the bacterium Propionibacterium acidipropionici becomes functional in S. cerevisiae when co-expressed with GroEL-GroES chaperonin complex from Escherichia coli. The developed strain BTY34, harboring the chaperonin complex, is able to efficiently convert xylose to ethanol with a yield of 0.44 g ethanol/g xylose. Furthermore, the BTY34 strain presents a xylose consumption rate similar to those observed for strains carrying the widely used XI from the fungus Orpinomyces sp. In addition, the tetrameric XI structure from P. acidipropionici showed an elevated number of hydrophobic amino acid residues on the surface of protein when compared to XI commonly expressed in S. cerevisiae. CONCLUSIONS Based on our results, we elaborate an extensive discussion concerning the uncertainties that surround heterologous expression of xylose isomerases in S. cerevisiae. Probably, a correct folding promoted by GroEL-GroES could solve some issues regarding a limited or absent XI activity in S. cerevisiae. The strains developed in this work have promising industrial characteristics, and the designed strategy could be an interesting approach to overcome the non-functionality of bacterial protein expression in yeasts.
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Affiliation(s)
- Beatriz Temer
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Leandro Vieira dos Santos
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
- CTBE – Brazilian Bioethanol Science and Technology Laboratory, Campinas, SP Brazil
| | - Victor Augusti Negri
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Juliana Pimentel Galhardo
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Pedro Henrique Mello Magalhães
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Juliana José
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Cidnei Marschalk
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Thamy Lívia Ribeiro Corrêa
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Marcelo Falsarella Carazzolle
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
| | - Gonçalo Amarante Guimarães Pereira
- Laboratory of Genomics and Expression, Department of Genetics and Evolution, Institute of Biology, UNICAMP, Campinas, São Paulo, 13083-970 Brazil
- CTBE – Brazilian Bioethanol Science and Technology Laboratory, Campinas, SP Brazil
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17
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Hou J, Qiu C, Shen Y, Li H, Bao X. Engineering of Saccharomyces cerevisiae for the efficient co-utilization of glucose and xylose. FEMS Yeast Res 2017; 17:3861258. [DOI: 10.1093/femsyr/fox034] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/02/2017] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jin Hou
- State Key Laboratory of Microbial Technology, The School of Life Science, Shandong University, Jinan, 250100, China
| | - Chenxi Qiu
- State Key Laboratory of Microbial Technology, The School of Life Science, Shandong University, Jinan, 250100, China
| | - Yu Shen
- State Key Laboratory of Microbial Technology, The School of Life Science, Shandong University, Jinan, 250100, China
| | - Hongxing Li
- State Key Laboratory of Microbial Technology, The School of Life Science, Shandong University, Jinan, 250100, China
- Shandong Provincial Key Laboratory of Microbial Engineering, Qi Lu University of Technology, Jinan, 250353, China
| | - Xiaoming Bao
- State Key Laboratory of Microbial Technology, The School of Life Science, Shandong University, Jinan, 250100, China
- Shandong Provincial Key Laboratory of Microbial Engineering, Qi Lu University of Technology, Jinan, 250353, China
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18
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Katahira S, Muramoto N, Moriya S, Nagura R, Tada N, Yasutani N, Ohkuma M, Onishi T, Tokuhiro K. Screening and evolution of a novel protist xylose isomerase from the termite Reticulitermes speratus for efficient xylose fermentation in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:203. [PMID: 28852424 PMCID: PMC5569483 DOI: 10.1186/s13068-017-0890-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/16/2017] [Indexed: 05/12/2023]
Abstract
BACKGROUND The yeast Saccharomyces cerevisiae, a promising host for lignocellulosic bioethanol production, is unable to metabolize xylose. In attempts to confer xylose utilization ability in S. cerevisiae, a number of xylose isomerase (XI) genes have been expressed heterologously in this yeast. Although several of these XI encoding genes were functionally expressed in S. cerevisiae, the need still exists for a S. cerevisiae strain with improved xylose utilization ability for use in the commercial production of bioethanol. Although currently much effort has been devoted to achieve the objective, one of the solutions is to search for a new XI gene that would confer superior xylose utilization in S. cerevisiae. Here, we searched for novel XI genes from the protists residing in the hindgut of the termite Reticulitermes speratus. RESULTS Eight novel XI genes were obtained from a cDNA library, prepared from the protists of the R. speratus hindgut, by PCR amplification using degenerated primers based on highly conserved regions of amino acid sequences of different XIs. Phylogenetic analysis classified these cloned XIs into two groups, one showed relatively high similarities to Bacteroidetes and the other was comparatively similar to Firmicutes. The growth rate and the xylose consumption rate of the S. cerevisiae strain expressing the novel XI, which exhibited highest XI activity among the eight XIs, were superior to those exhibited by the strain expressing the XI gene from Piromyces sp. E2. Substitution of the asparagine residue at position 337 of the novel XI with a cysteine further improved the xylose utilization ability of the yeast strain. Interestingly, introducing point mutations in the corresponding asparagine residues in XIs originated from other organisms, such as Piromyces sp. E2 or Clostridium phytofermentans, similarly improved xylose utilization in S. cerevisiae. CONCLUSIONS A novel XI gene conferring superior xylose utilization in S. cerevisiae was successfully isolated from the protists in the termite hindgut. Isolation of this XI gene and identification of the point mutation described in this study might contribute to improving the productivity of industrial bioethanol.
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Affiliation(s)
- Satoshi Katahira
- Bioinspired Systems Research-Domain, Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 Japan
| | - Nobuhiko Muramoto
- Bioinspired Systems Research-Domain, Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 Japan
| | - Shigeharu Moriya
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
| | - Risa Nagura
- Bioinspired Systems Research-Domain, Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 Japan
| | - Nobuki Tada
- Biotechnology and Afforestation Laboratory, New Business Planning Div, Toyota Motor Corporation, 1099 Marune, Kurozasa-cho, Miyoshi, Aichi 470-0201 Japan
| | - Noriko Yasutani
- Biotechnology and Afforestation Laboratory, New Business Planning Div, Toyota Motor Corporation, 1099 Marune, Kurozasa-cho, Miyoshi, Aichi 470-0201 Japan
| | - Moriya Ohkuma
- RIKEN Center for Sustainable Resource Science, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074 Japan
- Japan Collection of Microorganisms, RIKEN BioResource Center, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074 Japan
| | - Toru Onishi
- Biotechnology and Afforestation Laboratory, New Business Planning Div, Toyota Motor Corporation, 1099 Marune, Kurozasa-cho, Miyoshi, Aichi 470-0201 Japan
| | - Kenro Tokuhiro
- Bioinspired Systems Research-Domain, Toyota Central R&D Labs., Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192 Japan
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19
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Akbas MY, Stark BC. Recent trends in bioethanol production from food processing byproducts. J Ind Microbiol Biotechnol 2016; 43:1593-1609. [PMID: 27565674 DOI: 10.1007/s10295-016-1821-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 07/30/2016] [Indexed: 12/19/2022]
Abstract
The widespread use of corn starch and sugarcane as sources of sugar for the production of ethanol via fermentation may negatively impact the use of farmland for production of food. Thus, alternative sources of fermentable sugars, particularly from lignocellulosic sources, have been extensively investigated. Another source of fermentable sugars with substantial potential for ethanol production is the waste from the food growing and processing industry. Reviewed here is the use of waste from potato processing, molasses from processing of sugar beets into sugar, whey from cheese production, byproducts of rice and coffee bean processing, and other food processing wastes as sugar sources for fermentation to ethanol. Specific topics discussed include the organisms used for fermentation, strategies, such as co-culturing and cell immobilization, used to improve the fermentation process, and the use of genetic engineering to improve the performance of ethanol producing fermenters.
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Affiliation(s)
- Meltem Yesilcimen Akbas
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey. .,Institute of Biotechnology, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey.
| | - Benjamin C Stark
- Biology Department, Illinois Institute of Technology, Chicago, IL, 60616, USA
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20
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Moysés DN, Reis VCB, de Almeida JRM, de Moraes LMP, Torres FAG. Xylose Fermentation by Saccharomyces cerevisiae: Challenges and Prospects. Int J Mol Sci 2016; 17:207. [PMID: 26927067 PMCID: PMC4813126 DOI: 10.3390/ijms17030207] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 01/23/2016] [Accepted: 01/27/2016] [Indexed: 12/17/2022] Open
Abstract
Many years have passed since the first genetically modified Saccharomyces cerevisiae strains capable of fermenting xylose were obtained with the promise of an environmentally sustainable solution for the conversion of the abundant lignocellulosic biomass to ethanol. Several challenges emerged from these first experiences, most of them related to solving redox imbalances, discovering new pathways for xylose utilization, modulation of the expression of genes of the non-oxidative pentose phosphate pathway, and reduction of xylitol formation. Strategies on evolutionary engineering were used to improve fermentation kinetics, but the resulting strains were still far from industrial application. Lignocellulosic hydrolysates proved to have different inhibitors derived from lignin and sugar degradation, along with significant amounts of acetic acid, intrinsically related with biomass deconstruction. This, associated with pH, temperature, high ethanol, and other stress fluctuations presented on large scale fermentations led the search for yeasts with more robust backgrounds, like industrial strains, as engineering targets. Some promising yeasts were obtained both from studies of stress tolerance genes and adaptation on hydrolysates. Since fermentation times on mixed-substrate hydrolysates were still not cost-effective, the more selective search for new or engineered sugar transporters for xylose are still the focus of many recent studies. These challenges, as well as under-appreciated process strategies, will be discussed in this review.
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Affiliation(s)
- Danuza Nogueira Moysés
- Departamento de Biologia Celular, Universidade de Brasília, Brasília, DF 70910-900, Brazil.
- Petrobras Research and Development Center, Biotechnology Management, Rio de Janeiro, RJ 21941-915, Brazil.
| | | | - João Ricardo Moreira de Almeida
- Embrapa Agroenergia, Laboratório de Genética e Biotecnologia, Parque Estação Biológica s/n, Av. W3 Norte, Brasília, DF 70770-901, Brazil.
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21
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Knoshaug EP, Vidgren V, Magalhães F, Jarvis EE, Franden MA, Zhang M, Singh A. Novel transporters from
Kluyveromyces marxianus
and
Pichia guilliermondii
expressed in
Saccharomyces cerevisiae
enable growth on
l
‐arabinose and
d
‐xylose. Yeast 2015; 32:615-28. [DOI: 10.1002/yea.3084] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 05/11/2015] [Accepted: 06/23/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Eric P. Knoshaug
- National Renewable Energy Laboratory National Bioenergy Centre Golden CO USA
| | - Virve Vidgren
- VTT Technical Research Centre of Finland PO Box 1000 FI‐02044 VTT Finland
| | | | - Eric E. Jarvis
- National Renewable Energy Laboratory National Bioenergy Centre Golden CO USA
| | - Mary Ann Franden
- National Renewable Energy Laboratory National Bioenergy Centre Golden CO USA
| | - Min Zhang
- National Renewable Energy Laboratory National Bioenergy Centre Golden CO USA
| | - Arjun Singh
- National Renewable Energy Laboratory National Bioenergy Centre Golden CO USA
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22
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Engineering Saccharomyces pastorianus for the co-utilisation of xylose and cellulose from biomass. Microb Cell Fact 2015; 14:61. [PMID: 25928878 PMCID: PMC4417197 DOI: 10.1186/s12934-015-0242-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 04/08/2015] [Indexed: 01/24/2023] Open
Abstract
Background Lignocellulosic biomass is a viable source of renewable energy for bioethanol production. For the efficient conversion of biomass into bioethanol, it is essential that sugars from both the cellulose and hemicellulose fractions of lignocellulose be utilised. Results We describe the development of a recombinant yeast system for the fermentation of cellulose and xylose, the most abundant pentose sugar in the hemicellulose fraction of biomass. The brewer’s yeast Saccharomyces pastorianus was chosen as a host as significantly higher recombinant enzyme activities are achieved, when compared to the more commonly used S. cerevisiae. When expressed in S. pastorianus, the Trichoderma reesei xylose oxidoreductase pathway was more efficient at alcohol production from xylose than the xylose isomerase pathway. The alcohol yield was influenced by the concentration of xylose in the medium and was significantly improved by the additional expression of a gene encoding for xylulose kinase. The xylose reductase, xylitol dehydrogenase and xylulose kinase genes were co-expressed with genes encoding for the three classes of T. reesei cellulases, namely endoglucanase (EG2), cellobiohydrolysase (CBH2) and β-glucosidase (BGL1). The initial metabolism of xylose by the engineered strains facilitated production of cellulases at fermentation temperatures. The sequential metabolism of xylose and cellulose generated an alcohol yield of 82% from the available sugars. Several different types of biomass, such as the energy crop Miscanthus sinensis and the industrial waste, brewer’s spent grains, were examined as biomass sources for fermentation using the developed yeast strains. Xylose metabolism and cell growth were inhibited in fermentations carried out with acid-treated spent grain liquor, resulting in a 30% reduction in alcohol yield compared to fermentations carried out with mixed sugar substrates. Conclusions Reconstitution of complete enzymatic pathways for cellulose hydrolysis and xylose utilisation in S. pastorianus facilitates the co-fermentation of cellulose and xylose without the need for added exogenous cellulases and provides a basis for the development of a consolidated process for co-utilisation of hemicellulose and cellulose sugars. Electronic supplementary material The online version of this article (doi:10.1186/s12934-015-0242-4) contains supplementary material, which is available to authorized users.
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23
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Challenges for the production of bioethanol from biomass using recombinant yeasts. ADVANCES IN APPLIED MICROBIOLOGY 2015; 92:89-125. [PMID: 26003934 DOI: 10.1016/bs.aambs.2015.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lignocellulose biomass, one of the most abundant renewable resources on the planet, is an alternative sustainable energy source for the production of second-generation biofuels. Energy in the form of simple or complex carbohydrates can be extracted from lignocellulose biomass and fermented by microorganisms to produce bioethanol. Despite 40 years of active and cutting-edge research invested into the development of technologies to produce bioethanol from lignocellulosic biomass, the process remains commercially unviable. This review describes the achievements that have been made in generating microorganisms capable of utilizing both simple and complex sugars from lignocellulose biomass and the fermentation of these sugars into ethanol. We also provide a discussion on the current "roadblocks" standing in the way of making second-generation bioethanol a commercially viable alternative to fossil fuels.
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24
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Vilela LDF, de Araujo VPG, Paredes RDS, Bon EPDS, Torres FAG, Neves BC, Eleutherio ECA. Enhanced xylose fermentation and ethanol production by engineered Saccharomyces cerevisiae strain. AMB Express 2015; 5:16. [PMID: 25852993 PMCID: PMC4385029 DOI: 10.1186/s13568-015-0102-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/09/2015] [Indexed: 11/10/2022] Open
Abstract
We have recently demonstrated that heterologous expression of a bacterial xylose isomerase gene (xylA) of Burkholderia cenocepacia enabled a laboratorial Saccharomyces cerevisiae strain to ferment xylose anaerobically, without xylitol accumulation. However, the recombinant yeast fermented xylose slowly. In this study, an evolutionary engineering strategy was applied to improve xylose fermentation by the xylA-expressing yeast strain, which involved sequential batch cultivation on xylose. The resulting yeast strain co-fermented glucose and xylose rapidly and almost simultaneously, exhibiting improved ethanol production and productivity. It was also observed that when cells were grown in a medium containing higher glucose concentrations before being transferred to fermentation medium, higher rates of xylose consumption and ethanol production were obtained, demonstrating that xylose utilization was not regulated by catabolic repression. Results obtained by qPCR demonstrate that the efficiency in xylose fermentation showed by the evolved strain is associated, to the increase in the expression of genes HXT2 and TAL1, which code for a low-affinity hexose transporter and transaldolase, respectively. The ethanol productivity obtained after the introduction of only one genetic modification and the submission to a one-stage process of evolutionary engineering was equivalent to those of strains submitted to extensive metabolic and evolutionary engineering, providing solid basis for future applications of this strategy in industrial strains.
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25
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Kricka W, Fitzpatrick J, Bond U. Metabolic engineering of yeasts by heterologous enzyme production for degradation of cellulose and hemicellulose from biomass: a perspective. Front Microbiol 2014; 5:174. [PMID: 24795706 PMCID: PMC4001029 DOI: 10.3389/fmicb.2014.00174] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/31/2014] [Indexed: 11/13/2022] Open
Abstract
This review focuses on current approaches to metabolic engineering of ethanologenic yeast species for the production of bioethanol from complex lignocellulose biomass sources. The experimental strategies for the degradation of the cellulose and xylose-components of lignocellulose are reviewed. Limitations to the current approaches are discussed and novel solutions proposed.
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Affiliation(s)
- William Kricka
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
| | - James Fitzpatrick
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
| | - Ursula Bond
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
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26
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Li Z, Qu H, Li C, Zhou X. Direct and efficient xylitol production from xylan by Saccharomyces cerevisiae through transcriptional level and fermentation processing optimizations. BIORESOURCE TECHNOLOGY 2013; 149:413-419. [PMID: 24128404 DOI: 10.1016/j.biortech.2013.09.101] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/19/2013] [Accepted: 09/22/2013] [Indexed: 05/27/2023]
Abstract
In this study, four engineered Saccharomyces cerevisiae carrying xylanase, β-xylosidase and xylose reductase genes by different transcriptional regulations were constructed to directly convert xylan to xylitol. According to the results, the high-copy number plasmid required a rigid selection for promoter characteristics, on the contrast, the selection of promoters could be more flexible for low-copy number plasmid. For cell growth and xylitol production, glucose and galactose were found more efficient than other sugars. The semi-aerobic condition and feeding of co-substrates were taken to improve the yield of xylitol. It was found that the strain containing high-copy number plasmid had the highest xylitol yield, but it was sensitive to the change of fermentation. However, the strain carrying low-copy number plasmid was more adaptable to different processes. By optimization of the transcriptional regulation and fermentation processes, the xylitol concentration could be increased of 1.7 folds and the yield was 0.71 g xylitol/g xylan.
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Affiliation(s)
- Zhe Li
- School of Life Science, Beijing Institute of Technology, Beijing 100081, PR China
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