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Rastogi L, Chaudhari AA, Sharma R, Pawar PAM. Arabidopsis GELP7 functions as a plasma membrane-localized acetyl xylan esterase, and its overexpression improves saccharification efficiency. PLANT MOLECULAR BIOLOGY 2022; 109:781-797. [PMID: 35577991 DOI: 10.1007/s11103-022-01275-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Abstract
Acetyl substitution on the xylan chain is critical for stable interaction with cellulose and other cell wall polymers in the secondary cell wall. Xylan acetylation pattern is governed by Golgi and extracellular localized acetyl xylan esterase (AXE). We investigated the role of Arabidopsis clade Id from the GDSL esterase/lipase or GELP family in polysaccharide deacetylation. The investigation of the AtGELP7 T-DNA mutant line showed a decrease in stem esterase activity and an increase in stem acetyl content. We further generated overexpressor AtGELP7 transgenic lines, and these lines showed an increase in AXE activity and a decrease in xylan acetylation compared to wild-type plants. Therefore, we have named this enzyme as AtAXE1. The subcellular localization and immunoblot studies showed that the AtAXE1 enzyme is secreted out, associated with the plasma membrane and involved in xylan de-esterification post-synthesis. The cellulose digestibility was improved in AtAXE1 overexpressor lines without pre-treatment, after alkali and xylanases pre-treatment. Furthermore, we have also established that the AtGELP7 gene is upregulated in the overexpressor line of AtMYB46, a secondary cell wall specific transcription factor. This transcriptional regulation can drive AtGELP7 or AtAXE1 to perform de-esterification of xylan in a tissue-specific manner. Overall, these data suggest that AtGELP7 overexpression in Arabidopsis reduces xylan acetylation and improves digestibility properties of polysaccharides of stem lignocellulosic biomass.
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Affiliation(s)
- Lavi Rastogi
- Laboratory of Plant Cell Wall Biology, Regional Centre for Biotechnology, NCR Biotech Science, Cluster 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Aniket Anant Chaudhari
- Laboratory of Plant Cell Wall Biology, Regional Centre for Biotechnology, NCR Biotech Science, Cluster 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
| | - Raunak Sharma
- Laboratory of Plant Cell Wall Biology, Regional Centre for Biotechnology, NCR Biotech Science, Cluster 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India
- Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus, Hyderabad, Telangana, India
| | - Prashant Anupama-Mohan Pawar
- Laboratory of Plant Cell Wall Biology, Regional Centre for Biotechnology, NCR Biotech Science, Cluster 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad, Haryana, 121001, India.
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2
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Mavrommati M, Daskalaki A, Papanikolaou S, Aggelis G. Adaptive laboratory evolution principles and applications in industrial biotechnology. Biotechnol Adv 2021; 54:107795. [PMID: 34246744 DOI: 10.1016/j.biotechadv.2021.107795] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/11/2021] [Accepted: 07/05/2021] [Indexed: 12/20/2022]
Abstract
Adaptive laboratory evolution (ALE) is an innovative approach for the generation of evolved microbial strains with desired characteristics, by implementing the rules of natural selection as presented in the Darwinian Theory, on the laboratory bench. New as it might be, it has already been used by several researchers for the amelioration of a variety of characteristics of widely used microorganisms in biotechnology. ALE is used as a tool for the deeper understanding of the genetic and/or metabolic pathways of evolution. Another important field targeted by ALE is the manufacturing of products of (high) added value, such as ethanol, butanol and lipids. In the current review, we discuss the basic principles and techniques of ALE, and then we focus on studies where it has been applied to bacteria, fungi and microalgae, aiming to improve their performance to biotechnological procedures and/or inspect the genetic background of evolution. We conclude that ALE is a promising and efficacious method that has already led to the acquisition of useful new microbiological strains in biotechnology and could possibly offer even more interesting results in the future.
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Affiliation(s)
- Maria Mavrommati
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece; Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece
| | - Alexandra Daskalaki
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece
| | - Seraphim Papanikolaou
- Laboratory of Food Microbiology and Biotechnology, Department of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece
| | - George Aggelis
- Unit of Microbiology, Department of Biology, Division of Genetics, Cell Biology and Development, University of Patras, 26504 Patras, Greece.
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3
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Metabolic engineering of Zymomonas moblis for ethylene production from straw hydrolysate. Appl Microbiol Biotechnol 2021; 105:1709-1720. [PMID: 33512573 DOI: 10.1007/s00253-021-11091-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/27/2020] [Accepted: 01/03/2021] [Indexed: 10/22/2022]
Abstract
Biological ethylene production is a promising sustainable alternative approach for fossil-based ethylene production. The high glucose utilization of Z. mobilis makes it as a promising bioethylene producer. In this study, Zymomonas mobilis has been engineered to produce ethylene through the introduction of the synthetic ethylene-forming enzyme (EFE). We also investigated the effect of systematically knocking out the competitive metabolic pathway of pyruvate in an effort to improve the availability of pyruvate for ethylene production in Z. mobilis expressing EFE. Guided by these results, we tested a number of conjectures that could improve the α-ketoglutarate supply. Optimization of these pathways and different substrate supplies resulted in a greater production of ethylene (from 1.36 to 12.83 nmol/OD600/mL), which may guide future engineering work on ethylene production using other organisms. Meanwhile, we achieved an ethylene production of 5.8 nmol/OD600/mL in the ZM532-efe strain using enzymatic straw hydrolysate of corn straw as the sole carbon source. As a preferred host in biorefinery technologies using lignocellulosic biomass as feedstock, heterologous expression of EFE in Z. mobilis converts the non-ethylene producing strain into an ethylene-producing one using a metabolic engineering approach, which is of great significance for the utilization of cellulosic biomass in the future. KEY POINTS: • Heterologous expression of EFE in Z. mobilis successfully converted the non-ethylene producing strain into an ethylene producer (1.36 nmol/OD600/mL). Targeted modifications of the central carbon metabolism can effectively improve ethylene production (peak production: 8.3 nmol/OD600/mL). • The addition of nutrients to the medium can further increase the production of ethylene (peak production: 12.8 nmol/OD600/mL). • The ZM532-efe strain achieved an ethylene production of 5.8 nmol/OD600/mL when enzymatic hydrolysate of corn straw was used as the sole carbon source.
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4
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Pascoli DU, Suko A, Gustafson R, Gough HL, Bura R. Novel ethanol production using biomass preprocessing to increase ethanol yield and reduce overall costs. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:9. [PMID: 33413532 PMCID: PMC7789555 DOI: 10.1186/s13068-020-01839-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND Ethanol biorefineries need to lower their overall production costs to become economically feasible. Two strategies to achieve this are to reduce costs using cheaper feedstocks or to increase the ethanol production yield. Low-cost feedstocks usually have high non-structural components (NSC) content; therefore, a new process is necessary to accommodate these feedstocks and overcome the negative effects of NSC. This study developed a novel ethanol biorefinery process including a biomass preprocessing step that enabled the use of lower-cost feedstocks while improving ethanol production without detoxification (overliming). Two types of poplar feedstocks were used, low-quality whole-tree chips (WTC) and high-quality clean pulp chips (CPC), to determine if the proposed process is effective while using feedstocks with different NSC contents. RESULTS Technical assessment showed that acidic preprocessing increased the monomeric sugar recovery of WTC from 73.2% (untreated) to 87.5% due to reduced buffering capacity of poplar, improved sugar solubilization during pretreatment, and better enzymatic hydrolysis conversion. Preprocessing alone significantly improved the fermentability of the liquid fraction from 1-2% to 49-56% for both feedstocks while overliming improved it to 45%. Consequently, it was proposed that preprocessing can substitute for the detoxification step. The economic assessment revealed that using poplar WTC via the new process increased annual ethanol production of 10.5 million liters when compared to using CPC via overliming (base case scenario). Also, savings in total operating costs were about $10 million per year when using cheaper poplar WTC instead of CPC, and using recycled water for preprocessing lowered its total operating costs by 45-fold. CONCLUSIONS The novel process developed in this study was successful in increasing ethanol production while decreasing overall costs, thus facilitating the feasibility of lignocellulosic ethanol biorefineries. Key factors to achieving this outcome included substituting overliming by preprocessing, enabling the use of lower-quality feedstock, increasing monomeric sugar recovery and ethanol fermentation yield, and using recycled water for preprocessing. In addition, preprocessing enabled the implementation of an evaporator-combustor downstream design, resulting in a low-loading waste stream that can be treated in a wastewater treatment plant with a simple configuration.
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Affiliation(s)
- Danielle Uchimura Pascoli
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Azra Suko
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Rick Gustafson
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Heidi L. Gough
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
| | - Renata Bura
- School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100 USA
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Fehér A, Fehér C, Rozbach M, Rácz G, Fekete M, Hegedűs L, Barta Z. Treatments of Lignocellulosic Hydrolysates and Continuous-Flow Hydrogenation of Xylose to Xylitol. Chem Eng Technol 2017. [DOI: 10.1002/ceat.201700103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Anikó Fehér
- Budapest University of Technology and Economics; Department of Applied Biotechnology and Food Science; Faculty of Chemical Technology and Biotechnology; Szt. Gellért tér 4 1111 Budapest Hungary
| | - Csaba Fehér
- Budapest University of Technology and Economics; Department of Applied Biotechnology and Food Science; Faculty of Chemical Technology and Biotechnology; Szt. Gellért tér 4 1111 Budapest Hungary
| | - Margaréta Rozbach
- Budapest University of Technology and Economics; Department of Applied Biotechnology and Food Science; Faculty of Chemical Technology and Biotechnology; Szt. Gellért tér 4 1111 Budapest Hungary
| | - Gergely Rácz
- Budapest University of Technology and Economics; Department of Applied Biotechnology and Food Science; Faculty of Chemical Technology and Biotechnology; Szt. Gellért tér 4 1111 Budapest Hungary
| | - Melinda Fekete
- Enzymicals AG; Walther-Rathenau-Straße 49a 17489 Greifswald Germany
| | - László Hegedűs
- Budapest University of Technology and Economics and Hungarian Academy of Sciences; MTA-BME Organic Chemical Technology Research Group; Department of Organic Chemistry and Technology; Faculty of Chemical Technology and Biotechnology; Budafoki út 8 1111 Budapest Hungary
| | - Zsolt Barta
- Budapest University of Technology and Economics; Department of Applied Biotechnology and Food Science; Faculty of Chemical Technology and Biotechnology; Szt. Gellért tér 4 1111 Budapest Hungary
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6
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Speedy standing wave design, optimization, and scaling rules of simulated moving bed systems with linear isotherms. J Chromatogr A 2017; 1493:19-40. [DOI: 10.1016/j.chroma.2017.02.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 02/15/2017] [Accepted: 02/19/2017] [Indexed: 11/16/2022]
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7
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Lodi G, Storti G, Pellegrini LA, Morbidelli M. Ion Exclusion Chromatography: Model Development and Experimental Evaluation. Ind Eng Chem Res 2017. [DOI: 10.1021/acs.iecr.6b04475] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriele Lodi
- Dipartimento
di Chimica, Materiali e Ingegneria Chimica “G. Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Giuseppe Storti
- Institute
for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
| | - Laura A. Pellegrini
- Dipartimento
di Chimica, Materiali e Ingegneria Chimica “G. Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Massimo Morbidelli
- Institute
for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland
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Todhanakasem T, Tiwari R, Thanonkeo P. Development of corn silk as a biocarrier for Zymomonas mobilis biofilms in ethanol production from rice straw. J GEN APPL MICROBIOL 2016; 62:68-74. [DOI: 10.2323/jgam.62.68] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Pawar PMA, Derba-Maceluch M, Chong SL, Gómez LD, Miedes E, Banasiak A, Ratke C, Gaertner C, Mouille G, McQueen-Mason SJ, Molina A, Sellstedt A, Tenkanen M, Mellerowicz EJ. Expression of fungal acetyl xylan esterase in Arabidopsis thaliana improves saccharification of stem lignocellulose. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:387-97. [PMID: 25960248 DOI: 10.1111/pbi.12393] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 03/20/2015] [Accepted: 03/28/2015] [Indexed: 05/08/2023]
Abstract
Cell wall hemicelluloses and pectins are O-acetylated at specific positions, but the significance of these substitutions is poorly understood. Using a transgenic approach, we investigated how reducing the extent of O-acetylation in xylan affects cell wall chemistry, plant performance and the recalcitrance of lignocellulose to saccharification. The Aspergillus niger acetyl xylan esterase AnAXE1 was expressed in Arabidopsis under the control of either the constitutively expressed 35S CAMV promoter or a woody-tissue-specific GT43B aspen promoter, and the protein was targeted to the apoplast by its native signal peptide, resulting in elevated acetyl esterase activity in soluble and wall-bound protein extracts and reduced xylan acetylation. No significant alterations in cell wall composition were observed in the transgenic lines, but their xylans were more easily digested by a β-1,4-endoxylanase, and more readily extracted by hot water, acids or alkali. Enzymatic saccharification of lignocellulose after hot water and alkali pretreatments produced up to 20% more reducing sugars in several lines. Fermentation by Trametes versicolor of tissue hydrolysates from the line with a 30% reduction in acetyl content yielded ~70% more ethanol compared with wild type. Plants expressing 35S:AnAXE1 and pGT43B:AnAXE1 developed normally and showed increased resistance to the biotrophic pathogen Hyaloperonospora arabidopsidis, probably due to constitutive activation of defence pathways. However, unintended changes in xyloglucan and pectin acetylation were only observed in 35S:AnAXE1-expressing plants. This study demonstrates that postsynthetic xylan deacetylation in woody tissues is a promising strategy for optimizing lignocellulosic biomass for biofuel production.
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Affiliation(s)
- Prashant Mohan-Anupama Pawar
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Umeå, Sweden
| | - Marta Derba-Maceluch
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Umeå, Sweden
| | - Sun-Li Chong
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Leonardo D Gómez
- Center for Novel Agricultural Products Department of Biology, University of York, York, UK
| | - Eva Miedes
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Alicja Banasiak
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Christine Ratke
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Umeå, Sweden
| | - Cyril Gaertner
- Institut Jean-Pierre Bourgin UMR 1318 INRA/AgroParisTech, Saclay Plant Sciences, Centre de Versailles-Grignon, Versailles Cedex, France
| | - Grégory Mouille
- Institut Jean-Pierre Bourgin UMR 1318 INRA/AgroParisTech, Saclay Plant Sciences, Centre de Versailles-Grignon, Versailles Cedex, France
| | - Simon J McQueen-Mason
- Center for Novel Agricultural Products Department of Biology, University of York, York, UK
| | - Antonio Molina
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Anita Sellstedt
- Department of Plant Physiology, Umea University, Umeå Plant Science Centre, Umeå, Sweden
| | - Maija Tenkanen
- Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Ewa J Mellerowicz
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå Plant Science Centre, Umeå, Sweden
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Adaptive laboratory evolution of ethanologenic Zymomonas mobilis strain tolerant to furfural and acetic acid inhibitors. Appl Microbiol Biotechnol 2015; 99:5739-48. [PMID: 25935346 DOI: 10.1007/s00253-015-6616-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 04/12/2015] [Accepted: 04/15/2015] [Indexed: 12/17/2022]
Abstract
Furfural and acetic acid from lignocellulosic hydrolysates are the prevalent inhibitors to Zymomonas mobilis during cellulosic ethanol production. Developing a strain tolerant to furfural or acetic acid inhibitors is difficul by using rational engineering strategies due to poor understanding of their underlying molecular mechanisms. In this study, strategy of adaptive laboratory evolution (ALE) was used for development of a furfural and acetic acid-tolerant strain. After three round evolution, four evolved mutants (ZMA7-2, ZMA7-3, ZMF3-2, and ZMF3-3) that showed higher growth capacity were successfully obtained via ALE method. Based on the results of profiling of cell growth, glucose utilization, ethanol yield, and activity of key enzymes, two desired strains, ZMA7-2 and ZMF3-3, were achieved, which showed higher tolerance under 7 g/l acetic acid and 3 g/l furfural stress condition. Especially, it is the first report of Z. mobilis strain that could tolerate higher furfural. The best strain, Z. mobilis ZMF3-3, has showed 94.84% theoretical ethanol yield under 3-g/l furfural stress condition, and the theoretical ethanol yield of ZM4 is only 9.89%. Our study also demonstrated that ALE method might also be used as a powerful metabolic engineering tool for metabolic engineering in Z. mobilis. Furthermore, the two best strains could be used as novel host for further metabolic engineering in cellulosic ethanol or future biorefinery. Importantly, the two strains may also be used as novel-tolerant model organisms for the genetic mechanism on the "omics" level, which will provide some useful information for inverse metabolic engineering.
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11
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Shaw AJ, Miller BB, Rogers SR, Kenealy WR, Meola A, Bhandiwad A, Sillers WR, Shikhare I, Hogsett DA, Herring CD. Anaerobic detoxification of acetic acid in a thermophilic ethanologen. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:75. [PMID: 27279899 PMCID: PMC4898469 DOI: 10.1186/s13068-015-0257-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 04/24/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield. RESULTS We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum. The first steps of the pathway, a reversible conversion of acetate to acetyl-CoA, are catalyzed by the native T. saccharolyticum enzymes acetate kinase and phosphotransacetylase. ack and pta normally divert 30% of catabolic carbon flux to acetic acid; however, their re-introduction in evolved ethanologen strains resulted in virtually no acetic acid production. Conversion between acetic acid and acetyl-CoA remained active, as evidenced by rapid (13)C label transfer from exogenous acetate to ethanol. Genomic re-sequencing of six independently evolved ethanologen strains showed convergent mutations in the hfs hydrogenase gene cluster, which when transferred to wildtype T. saccharolyticum conferred a low acid production phenotype. Thus, the mutated hfs genes effectively separate acetic acid production and consumption from central metabolism, despite their intersecting at the common intermediate acetyl-CoA. To drive acetic acid conversion to a less inhibitory product, the enzymes thiolase, acetoacetate:acetate CoA-transferase, and acetoacetate decarboxylase were assembled in T. saccharolyticum with genes from thermophilic donor organisms that do not natively produce acetone. The resultant strain converted acetic acid to acetone and ethanol while maintaining a metabolic yield of 0.50 g ethanol per gram carbohydrate. CONCLUSIONS Conversion of acetic acid to acetone results in improved ethanol productivity and titer and is an attractive low-cost solution to acetic acid inhibition.
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Affiliation(s)
- A Joe Shaw
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Novogy Inc., 85 Bolton St, Cambridge, MA 02140 USA
| | | | | | - William R Kenealy
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Verdezyne Inc., 2715 Loker Avenue West, Carlsbad, CA 92010 USA
| | - Alex Meola
- />Mascoma Corporation, Lebanon, NH 03766 USA
| | - Ashwini Bhandiwad
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
- />Energy Biosciences Institute, 2151 Berkeley Way, Berkeley, CA 94704 USA
| | - W Ryan Sillers
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Myriant Corporation, 66 Cummings Park, Woburn, MA 01801 USA
| | | | - David A Hogsett
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />OPX Biotechnologies Inc., 2425 55th Street, Boulder, CO 80301 USA
| | - Christopher D Herring
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
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12
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Yi X, Gu H, Gao Q, Liu ZL, Bao J. Transcriptome analysis of Zymomonas mobilis ZM4 reveals mechanisms of tolerance and detoxification of phenolic aldehyde inhibitors from lignocellulose pretreatment. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:153. [PMID: 26396591 PMCID: PMC4578398 DOI: 10.1186/s13068-015-0333-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/03/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Phenolic aldehydes generated from lignocellulose pretreatment exhibited severe toxic inhibitions on microbial growth and fermentation. Numerous tolerance studies against furfural, 5-hydroxymethyl-2-furaldehyde (HMF), acetate, and ethanol were reported, but studies on inhibition of phenolic aldehyde inhibitors are rare. For ethanologenic strains, Zymomonas mobilis ZM4 is high in ethanol productivity and genetic manipulation feasibility, but sensitive to phenolic aldehyde inhibitors. Molecular mechanisms of tolerance for Z. mobilis toward phenolic aldehydes are not known. RESULTS We took the first insight into genomic response of Z. mobilis ZM4 to the phenolic aldehyde inhibitors derived from lignocellulose pretreatment. The results suggest that the toxicity to cells is caused by the functional group of phenolic aldehyde, similar to furfural and HMF, rather than aromatic groups or phenolic hydroxyl groups. Transcriptome response against 4-hydroxybenzaldehyde, syringaldehyde, and vanillin, representing phenolic groups H, S, and G, respectively, was investigated. The atlas of the important genes responsible for significantly enhanced and repressed genes at the genomic level was illustrated. 272 genes with twofold greater expressions than non-treated controls and 36 gene clusters in response to challenges of these phenolic aldehydes were identified. Several reductases encoded by ZMO1116, ZMO1696, and ZMO1885 were found to play the key roles in reducing phenolic aldehydes into the corresponding phenolic alcohols. Reduction of phenolic aldehydes by overexpression of ZMO1116, ZMO1696, and ZMO1885 in Z. mobilis ZM4 resulted in the increased inhibitor conversion and ethanol productivity, especially for 4-hydroxybenzaldehyde and vanillin. Several transporter genes such as ZMO0282, ZMO0283, ZMO0798, ZMO0799, and ZMO0800 was also displayed significantly increased expressions against the phenolic aldehydes. CONCLUSIONS The genes encoding reductases are with potentials on phenolic aldehydes-tolerant genes contributing to the reduction of phenolic aldehydes into the corresponding phenolic alcohols forms for Z. mobilis ZM4. Overexpression of the key genes improved the conversion ratio and ethanol productivity of 4-hydroxybenzaldehyde and vanillin with high toxicity. New knowledge obtained from this research aids understanding the mechanisms of bacterial tolerance and the development of the next-generation biocatalysts for advanced biofuels production.
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Affiliation(s)
- Xia Yi
- />State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
| | - Hanqi Gu
- />State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
| | - Qiuqiang Gao
- />State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
| | - Z. Lewis Liu
- />US Department of Agriculture, Agricultural Research Service, National Center for Agricultural Utilization Research, 1815 North University Street, Peoria, IL 61604 USA
| | - Jie Bao
- />State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
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Ma J, Li F, Liu R, Liang L, Ji Y, Wei C, Jiang M, Jia H, Ouyang P. Succinic acid production from sucrose and molasses by metabolically engineered E. coli using a cell surface display system. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2014.08.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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14
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Todhanakasem T, Sangsutthiseree A, Areerat K, Young GM, Thanonkeo P. Biofilm production by Zymomonas mobilis enhances ethanol production and tolerance to toxic inhibitors from rice bran hydrolysate. N Biotechnol 2014; 31:451-9. [PMID: 24930397 DOI: 10.1016/j.nbt.2014.06.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 05/25/2014] [Accepted: 06/01/2014] [Indexed: 11/30/2022]
Abstract
Microorganisms play a significant role in bioethanol production from lignocellulosic material. A challenging problem in bioconversion of rice bran is the presence of toxic inhibitors in lignocellulosic acid hydrolysate. Various strains of Zymomonas mobilis (ZM4, TISTR 405, 548, 550 and 551) grown under biofilm or planktonic modes were used in this study to examine their potential for bioconversion of rice bran hydrolysate and ethanol production efficiencies. Z. mobilis readily formed bacterial attachment on plastic surfaces, but not on glass surfaces. Additionally, the biofilms formed on plastic surfaces steadily increased over time, while those formed on glass were speculated to cycle through accumulation and detachment phases. Microscopic analysis revealed that Z. mobilis ZM4 rapidly developed homogeneous biofilm structures within 24 hours, while other Z. mobilis strains developed heterogeneous biofilm structures. ZM4 biofilms were thicker and seemed to be more stable than other Z. mobilis strains. The percentage of live cells in biofilms was greater than that for planktonic cells (54.32 ± 7.10% vs. 28.69 ± 3.03%), suggesting that biofilms serve as a protective niche for growth of bacteria in the presence of toxic inhibitors in the rice bran hydrolysate. The metabolic activity of ZM4 grown as a biofilm was also higher than the same strain grown planktonically, as measured by ethanol production from rice bran hydrolysate (13.40 ± 2.43 g/L vs. 0.432 ± 0.29 g/L, with percent theoretical ethanol yields of 72.47 ± 6.13% and 3.71 ± 5.24% respectively). Strain TISTR 551 was also quite metabolically active, with ethanol production by biofilm and planktonically grown cells of 8.956 ± 4.06 g/L and 0.0846 ± 0.064 g/L (percent theoretical yields were 48.37 ± 16.64% and 2.046 ± 1.58%, respectively). This study illustrates the potential for enhancing ethanol production by utilizing bacterial biofilms in the bioconversion of a readily available and normally unusable low value by-product of rice farming.
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Affiliation(s)
| | | | | | - Glenn M Young
- Food Science and Technology, University of California, Davis 95616, USA
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Zha Y, Westerhuis JA, Muilwijk B, Overkamp KM, Nijmeijer BM, Coulier L, Smilde AK, Punt PJ. Identifying inhibitory compounds in lignocellulosic biomass hydrolysates using an exometabolomics approach. BMC Biotechnol 2014; 14:22. [PMID: 24655423 PMCID: PMC3998114 DOI: 10.1186/1472-6750-14-22] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/27/2014] [Indexed: 12/16/2022] Open
Abstract
Background Inhibitors are formed that reduce the fermentation performance of fermenting yeast during the pretreatment process of lignocellulosic biomass. An exometabolomics approach was applied to systematically identify inhibitors in lignocellulosic biomass hydrolysates. Results We studied the composition and fermentability of 24 different biomass hydrolysates. To create diversity, the 24 hydrolysates were prepared from six different biomass types, namely sugar cane bagasse, corn stover, wheat straw, barley straw, willow wood chips and oak sawdust, and with four different pretreatment methods, i.e. dilute acid, mild alkaline, alkaline/peracetic acid and concentrated acid. Their composition and that of fermentation samples generated with these hydrolysates were analyzed with two GC-MS methods. Either ethyl acetate extraction or ethyl chloroformate derivatization was used before conducting GC-MS to prevent sugars are overloaded in the chromatograms, which obscure the detection of less abundant compounds. Using multivariate PLS-2CV and nPLS-2CV data analysis models, potential inhibitors were identified through establishing relationship between fermentability and composition of the hydrolysates. These identified compounds were tested for their effects on the growth of the model yeast, Saccharomyces. cerevisiae CEN.PK 113-7D, confirming that the majority of the identified compounds were indeed inhibitors. Conclusion Inhibitory compounds in lignocellulosic biomass hydrolysates were successfully identified using a non-targeted systematic approach: metabolomics. The identified inhibitors include both known ones, such as furfural, HMF and vanillin, and novel inhibitors, namely sorbic acid and phenylacetaldehyde.
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Affiliation(s)
| | | | | | | | | | | | | | - Peter J Punt
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist 3704 HE, The Netherlands.
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Shekiro III J, Kuhn EM, Nagle NJ, Tucker MP, Elander RT, Schell DJ. Characterization of pilot-scale dilute acid pretreatment performance using deacetylated corn stover. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:23. [PMID: 24548527 PMCID: PMC3942107 DOI: 10.1186/1754-6834-7-23] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/06/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND Dilute acid pretreatment is a promising process technology for the deconstruction of low-lignin lignocellulosic biomass, capable of producing high yields of hemicellulosic sugars and enhancing enzymatic yields of glucose as part of a biomass-to-biofuels process. However, while it has been extensively studied, most work has historically been conducted at relatively high acid concentrations of 1 - 4% (weight/weight). Reducing the effective acid loading in pretreatment has the potential to reduce chemical costs both for pretreatment and subsequent neutralization. Additionally, if acid loadings are sufficiently low, capital requirements associated with reactor construction may be significantly reduced due to the relaxation of requirements for exotic alloys. Despite these benefits, past efforts have had difficulty obtaining high process yields at low acid loadings without supplementation of additional unit operations, such as mechanical refining. RESULTS Recently, we optimized the dilute acid pretreatment of deacetylated corn stover at low acid loadings in a 1-ton per day horizontal pretreatment reactor. This effort included more than 25 pilot-scale pretreatment experiments executed at reactor temperatures ranging from 150 - 170°C, residence times of 10 - 20 minutes and hydrolyzer sulfuric acid concentrations between 0.15 - 0.30% (weight/weight). In addition to characterizing the process yields achieved across the reaction space, the optimization identified a pretreatment reaction condition that achieved total xylose yields from pretreatment of 73.5% ± 1.5% with greater than 97% xylan component balance closure across a series of five runs at the same condition. Feedstock reactivity at this reaction condition after bench-scale high solids enzymatic hydrolysis was 77%, prior to the inclusion of any additional conversion that may occur during subsequent fermentation. CONCLUSIONS This study effectively characterized a range of pretreatment reaction conditions using deacetylated corn stover at low acid loadings and identified an optimum reaction condition was selected and used in a series of integrated pilot scale cellulosic ethanol production campaigns. Additionally, several issues exist to be considered in future pretreatment experiments in continuous reactor systems, including the formation of char within the reactor, as well as practical issues with feeding herbaceous feedstock into pressurized systems.
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Affiliation(s)
- Joseph Shekiro III
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
| | - Erik M Kuhn
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
| | - Nicholas J Nagle
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
| | - Melvin P Tucker
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
| | - Richard T Elander
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
| | - Daniel J Schell
- National Bioenergy Center, National Renewable Energy Laboratory, 617 Cole Blvd, 80401 Golden, CO, USA
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Wang L, Tang P, Fan X, Yuan Q. Effect of selected aldehydes found in the corncob hemicellulose hydrolysate on the growth and xylitol fermentation of Candida tropicalis. Biotechnol Prog 2013; 29:1181-9. [PMID: 23843370 DOI: 10.1002/btpr.1774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 05/12/2013] [Indexed: 11/09/2022]
Abstract
The effects of four aldehydes (furfural, 5-hydroxymethylfurfural, vanillin and syringaldehyde), which were found in the corncob hemicellulose hydrolysate, on the growth and xylitol fermentation of Candida tropicalis were investigated. The results showed that vanillin was the most toxic aldehyde for the xylitol fermentation, followed by syringaldehyde, furfural and 5-hydroxymethylfurfural. Moreover, the binary combination tests revealed that furfural amplified the toxicity of other aldehydes and the toxicities of other binary combinations without furfural were simply additive. Based on the fermentation experiments, it was demonstrated that the inhibition of aldehydes could be alleviated by prolonging the fermentation incubation, increasing the initial cell concentration, enhancing the initial pH value and minimizing the furfural levels in the hydrolysate evaporation process. The strategies that we proposed to suppress the inhibitory effects of the aldehydes successfully avoided the complicated and costly detoxifications. Our findings could be potentially adopted for the industrial xylitol fermentation from hydrolysates.
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Affiliation(s)
- Le Wang
- State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, 100029, Beijing, China; College of Bioengineering, Henan University of Technology, 450000, Zhengzhou, China
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Franden MA, Pilath HM, Mohagheghi A, Pienkos PT, Zhang M. Inhibition of growth of Zymomonas mobilis by model compounds found in lignocellulosic hydrolysates. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:99. [PMID: 23837621 PMCID: PMC3716709 DOI: 10.1186/1754-6834-6-99] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 06/24/2013] [Indexed: 05/18/2023]
Abstract
BACKGROUND During the pretreatment of biomass feedstocks and subsequent conditioning prior to saccharification, many toxic compounds are produced or introduced which inhibit microbial growth and in many cases, production of ethanol. An understanding of the toxic effects of compounds found in hydrolysate is critical to improving sugar utilization and ethanol yields in the fermentation process. In this study, we established a useful tool for surveying hydrolysate toxicity by measuring growth rates in the presence of toxic compounds, and examined the effects of selected model inhibitors of aldehydes, organic and inorganic acids (along with various cations), and alcohols on growth of Zymomonas mobilis 8b (a ZM4 derivative) using glucose or xylose as the carbon source. RESULTS Toxicity strongly correlated to hydrophobicity in Z. mobilis, which has been observed in Escherichia coli and Saccharomyces cerevisiae for aldehydes and with some exceptions, organic acids. We observed Z. mobilis 8b to be more tolerant to organic acids than previously reported, although the carbon source and growth conditions play a role in tolerance. Growth in xylose was profoundly inhibited by monocarboxylic organic acids compared to growth in glucose, whereas dicarboxylic acids demonstrated little or no effects on growth rate in either substrate. Furthermore, cations can be ranked in order of their toxicity, Ca++ > > Na+ > NH4+ > K+. HMF (5-hydroxymethylfurfural), furfural and acetate, which were observed to contribute to inhibition of Z. mobilis growth in dilute acid pretreated corn stover hydrolysate, do not interact in a synergistic manner in combination. We provide further evidence that Z. mobilis 8b is capable of converting the aldehydes furfural, vanillin, 4-hydroxybenzaldehyde and to some extent syringaldehyde to their alcohol forms (furfuryl, vanillyl, 4-hydroxybenzyl and syringyl alcohol) during fermentation. CONCLUSIONS Several key findings in this report provide a mechanism for predicting toxic contributions of inhibitory components of hydrolysate and provide guidance for potential process development, along with potential future strain improvement and tolerance strategies.
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Affiliation(s)
- Mary Ann Franden
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
| | - Heidi M Pilath
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
| | - Ali Mohagheghi
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
| | - Philip T Pienkos
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
| | - Min Zhang
- National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401, USA
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Chang S, Park S, Kang D. Development of novel agar media for isolating guaiacol producing Alicyclobacillus spp. Int J Food Microbiol 2013; 164:1-6. [DOI: 10.1016/j.ijfoodmicro.2013.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 03/04/2013] [Accepted: 03/16/2013] [Indexed: 11/30/2022]
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RETRACTED ARTICLE: Recent advancement in production of liquid biofuels from renewable resources: a review. RESEARCH ON CHEMICAL INTERMEDIATES 2013. [DOI: 10.1007/s11164-013-1231-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Moreno MS, Andersen FE, Díaz MS. Dynamic Modeling and Parameter Estimation for Unit Operations in Lignocellulosic Bioethanol Production. Ind Eng Chem Res 2013. [DOI: 10.1021/ie302358e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Susana Moreno
- Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET—Universidad Nacional del Sur, Camino
La Carrindanga km 7, 8000 Bahía Blanca, Argentina
| | - Federico E. Andersen
- Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET—Universidad Nacional del Sur, Camino
La Carrindanga km 7, 8000 Bahía Blanca, Argentina
| | - M. Soledad Díaz
- Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET—Universidad Nacional del Sur, Camino
La Carrindanga km 7, 8000 Bahía Blanca, Argentina
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Zha Y, Punt PJ. Exometabolomics approaches in studying the application of lignocellulosic biomass as fermentation feedstock. Metabolites 2013; 3:119-43. [PMID: 24957893 PMCID: PMC3901257 DOI: 10.3390/metabo3010119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/13/2012] [Accepted: 01/28/2013] [Indexed: 11/16/2022] Open
Abstract
Lignocellulosic biomass is the future feedstock for the production of biofuel and bio-based chemicals. The pretreatment-hydrolysis product of biomass, so-called hydrolysate, contains not only fermentable sugars, but also compounds that inhibit its fermentability by microbes. To reduce the toxicity of hydrolysates as fermentation media, knowledge of the identity of inhibitors and their dynamics in hydrolysates need to be obtained. In the past decade, various studies have applied targeted metabolomics approaches to examine the composition of biomass hydrolysates. In these studies, analytical methods like HPLC, RP-HPLC, CE, GC-MS and LC-MS/MS were used to detect and quantify small carboxylic acids, furans and phenols. Through applying targeted metabolomics approaches, inhibitors were identified in hydrolysates and their dynamics in fermentation processes were monitored. However, to reveal the overall composition of different hydrolysates and to investigate its influence on hydrolysate fermentation performance, a non-targeted metabolomics study needs to be conducted. In this review, a non-targeted and generic metabolomics approach is introduced to explore inhibitor identification in biomass hydrolysates, and other similar metabolomics questions.
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Affiliation(s)
- Ying Zha
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist, 3704 HE, The Netherlands.
| | - Peter J Punt
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist, 3704 HE, The Netherlands.
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Removal of acetic acid and sulfuric acid from biomass hydrolyzate using a lime addition–capacitive deionization (CDI) hybrid process. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.07.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Intriago P. Marine Microorganisms: perspectives for getting involved in cellulosic ethanol. AMB Express 2012; 2:46. [PMID: 22931793 PMCID: PMC3490849 DOI: 10.1186/2191-0855-2-46] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 07/30/2012] [Indexed: 11/10/2022] Open
Abstract
The production of ethanol has been considered as an alternative to replace part of the petroleum derivate. Brazil and the US are the leading producers, but more environmentally friendly alternatives are needed. Lignocellulose has an enormous potential but technology has to be still improve in order to economically produce ethanol. The present paper reviews the potential and problems of this technology and proposes the study of a group of microorganisms with the largest genetic pool, marine microorganism.
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Chakraborty S, Aggarwal V, Mukherjee D, Andras K. Biomass to biofuel: a review on production technology. ASIA-PAC J CHEM ENG 2012. [DOI: 10.1002/apj.1642] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sudip Chakraborty
- Research Institute on Membrane Technology, CNR-ITM; c/o University of Calabria; Via P. Bucci, Cubo-17/C; 87036; Rende (CS); Italy
| | - Varun Aggarwal
- Department of Chemical Engineering, Indian Institute of Technology; Kharagpur; 721 302; West Bengal; India
| | - Debolina Mukherjee
- Department of Geological Sciences; University of Calabria; Cubo-15B,Via-P. Bucci; 87036; Rende (CS); Italy
| | - Koris Andras
- Department of Food Engineering, Faculty of Food Science; Corvinus University of Budapest; Ménesi út 44; Budapest; H-1118; Hungary
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Zheng Y, Yu X, Zeng J, Chen S. Feasibility of filamentous fungi for biofuel production using hydrolysate from dilute sulfuric acid pretreatment of wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:50. [PMID: 22824058 PMCID: PMC3463428 DOI: 10.1186/1754-6834-5-50] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 07/02/2012] [Indexed: 05/25/2023]
Abstract
BACKGROUND Lipids produced from filamentous fungi show great promise for biofuel production, but a major limiting factor is the high production cost attributed to feedstock. Lignocellulosic biomass is a suitable feedstock for biofuel production due to its abundance and low value. However, very limited study has been performed on lipid production by culturing oleaginous fungi with lignocellulosic materials. Thus, identification of filamentous fungal strains capable of utilizing lignocellulosic hydrolysates for lipid accumulation is critical to improve the process and reduce the production cost. RESULTS The growth performances of eleven filamentous fungi were investigated when cultured on glucose and xylose. Their dry cell weights, lipid contents and fatty acid profiles were determined. Six fungal strains with high lipid contents were selected to culture with the hydrolysate from dilute sulfuric acid pretreatment of wheat straw. The results showed that all the selected fungal strains were able to grow on both detoxified liquid hydrolysate (DLH) and non-detoxified liquid hydrolysate (NDLH). The highest lipid content of 39.4% was obtained by Mortierella isabellina on NDLH. In addition, NDLH with some precipitate could help M. isabellina form pellets with an average diameter of 0.11 mm. CONCLUSION This study demonstrated the possibility of fungal lipid production from lignocellulosic biomass. M. isabellina was the best lipid producer grown on lignocellulosic hydrolysates among the tested filamentous fungi, because it could not only accumulate oils with a high content by directly utilizing NDLH to simplify the fermentation process, but also form proper pellets to benefit the downstream harvesting. Considering the yield and cost, fungal lipids from lignocellulosic biomass are promising alternative sources for biodiesel production.
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Affiliation(s)
- Yubin Zheng
- Department of Biological Systems Engineering, L.J. Smith Hall, Washington State University, Pullman, WA, 99164-6120, USA
| | - Xiaochen Yu
- Department of Biological Systems Engineering, L.J. Smith Hall, Washington State University, Pullman, WA, 99164-6120, USA
| | - Jijiao Zeng
- Department of Biological Systems Engineering, L.J. Smith Hall, Washington State University, Pullman, WA, 99164-6120, USA
| | - Shulin Chen
- Department of Biological Systems Engineering, L.J. Smith Hall, Washington State University, Pullman, WA, 99164-6120, USA
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He MX, Wu B, Shui ZX, Hu QC, Wang WG, Tan FR, Tang XY, Zhu QL, Pan K, Li Q, Su XH. Transcriptome profiling of Zymomonas mobilis under furfural stress. Appl Microbiol Biotechnol 2012; 95:189-99. [PMID: 22592554 DOI: 10.1007/s00253-012-4155-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 05/03/2012] [Accepted: 05/03/2012] [Indexed: 11/24/2022]
Abstract
Furfural from lignocellulosic hydrolysates is the prevalent inhibitor to microorganisms during cellulosic ethanol production, but the molecular mechanisms of tolerance to this inhibitor in Zymomonas mobilis are still unclear. In this study, genome-wide transcriptional responses to furfural were investigated in Z. mobilis using microarray analysis. We found that 433 genes were differentially expressed in response to furfural. Furfural up- or down-regulated genes related to cell wall/membrane biogenesis, metabolism, and transcription. However, furfural has a subtle negative effect on Entner-Doudoroff pathway mRNAs. Our results revealed that furfural had effects on multiple aspects of cellular metabolism at the transcriptional level and that membrane might play important roles in response to furfural. This research has provided insights into the molecular response to furfural in Z. mobilis, and it will be helpful to construct more furfural-resistant strains for cellulosic ethanol production.
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Affiliation(s)
- Ming-xiong He
- Biomass Energy Technology Research Centre, Biogas Institute of Ministry of Agriculture, Section 4-13, Renming Nanlu, Chengdu 610041, China.
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Nam HG, Mun S. Optimal design and experimental validation of a three-zone simulated moving bed process based on the Amberchrom-CG161C adsorbent for continuous removal of acetic acid from biomass hydrolyzate. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.01.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Chen X, Shekiro J, Franden MA, Wang W, Zhang M, Kuhn E, Johnson DK, Tucker MP. The impacts of deacetylation prior to dilute acid pretreatment on the bioethanol process. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:8. [PMID: 22369467 DOI: 10.1186/1754-6834-1185-1188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 02/27/2012] [Indexed: 05/28/2023]
Abstract
BACKGROUND Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: 1) cleavage of the xylosidic bonds, and 2) cleavage of covalently bonded acetyl ester groups. RESULTS In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustness of the deacetylation-pretreatment-saccharification-fermentation process. CONCLUSIONS Deacetylation shows significant improvement on glucose and xylose yields during pretreatment and enzymatic hydrolysis, but it also reduces hydrolyzate toxicity during fermentation, thereby improving ethanol yields and titer. The magnitude of effect is dependent on the selected corn stover variety, with several varieties achieving improvements of greater than 10% xylose yield in pretreatment, 20% glucose yield in low solids enzymatic hydrolysis and 7% overall ethanol yield.
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Affiliation(s)
- Xiaowen Chen
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA.
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30
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Chen X, Shekiro J, Franden MA, Wang W, Zhang M, Kuhn E, Johnson DK, Tucker MP. The impacts of deacetylation prior to dilute acid pretreatment on the bioethanol process. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:8. [PMID: 22369467 PMCID: PMC3309953 DOI: 10.1186/1754-6834-5-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 02/27/2012] [Indexed: 05/02/2023]
Abstract
BACKGROUND Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: 1) cleavage of the xylosidic bonds, and 2) cleavage of covalently bonded acetyl ester groups. RESULTS In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustness of the deacetylation-pretreatment-saccharification-fermentation process. CONCLUSIONS Deacetylation shows significant improvement on glucose and xylose yields during pretreatment and enzymatic hydrolysis, but it also reduces hydrolyzate toxicity during fermentation, thereby improving ethanol yields and titer. The magnitude of effect is dependent on the selected corn stover variety, with several varieties achieving improvements of greater than 10% xylose yield in pretreatment, 20% glucose yield in low solids enzymatic hydrolysis and 7% overall ethanol yield.
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Affiliation(s)
- Xiaowen Chen
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Joseph Shekiro
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Mary Ann Franden
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Wei Wang
- Biosciences Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Min Zhang
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Erik Kuhn
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - David K Johnson
- Biosciences Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
| | - Melvin P Tucker
- National Bioenergy Center, National Renewable Energy Lab, 1617 Cole Blvd, Golden, CO 80127, USA
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Taylor MP, Mulako I, Tuffin M, Cowan D. Understanding physiological responses to pre-treatment inhibitors in ethanologenic fermentations. Biotechnol J 2012; 7:1169-81. [PMID: 22331581 DOI: 10.1002/biot.201100335] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 12/15/2011] [Accepted: 01/17/2012] [Indexed: 11/10/2022]
Abstract
Alcohol-based liquid fuels feature significantly in the political and social agendas of many countries, seeking energy sustainability. It is certain that ethanol will be the entry point for many sustainable processes. Conventional ethanol production using maize- and sugarcane-based carbohydrates with Saccharomyces cerevisiae is well established, while lignocellulose-based processes are receiving growing interest despite posing greater technical and scientific challenges. A significant challenge that arises from the chemical hydrolysis of lignocellulose is the generation of toxic compounds in parallel with the release of sugars. These compounds, collectively termed pre-treatment inhibitors, impair metabolic functionality and growth. Their removal, pre-fermentation or their abatement, via milder hydrolysis, are currently uneconomic options. It is widely acknowledged that a more cost effective strategy is to develop resistant process strains. Here we describe and classify common inhibitors and describe in detail the reported physiological responses that occur in second-generation strains, which include engineered yeast and mesophilic and thermophilic prokaryotes. It is suggested that a thorough understanding of tolerance to common pre-treatment inhibitors should be a major focus in ongoing strain engineering. This review is a useful resource for future metabolic engineering strategies.
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Affiliation(s)
- Mark P Taylor
- TMO Renewables Ltd., The Surrey Research Park, Guildford, UK
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Fermentation of reactive-membrane-extracted and ammonium-hydroxide-conditioned dilute-acid-pretreated corn stover. Appl Biochem Biotechnol 2011; 166:470-8. [PMID: 22161211 DOI: 10.1007/s12010-011-9442-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 10/26/2011] [Indexed: 01/14/2023]
Abstract
Acid-pretreated biomass contains various compounds (acetic acid, etc.) that are inhibitory to fermentative microorganisms. Removing or deactivating these compounds using detoxification methods such as overliming or ammonium hydroxide conditioning (AHC) improves sugar-to-ethanol yields. In this study, we treated the liquor fraction of dilute-acid-pretreated corn stover using AHC and a new reactive membrane extraction technique, both separately and in combination, and then the sugars in the treated liquors were fermented to ethanol with the glucose-xylose-fermenting bacterium, Zymomonas mobilis 8b. We performed reactive extraction with mixtures of octanol/Alamine 336 or oleyl alcohol/Alamine 336. The best ethanol yields and rates were achieved for oleyl alcohol-extracted hydrolysates followed by AHC hydrolysates, while octanol-extracted hydrolysates were unfermentable because highly toxic octanol was found in the hydrolysate. Adding olive oil significantly improved yields for octanol-extracted hydrolysate. Additional work is underway to determine if this technology is a cost-effective alternative to traditional hydrolysate conditioning processes.
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Chen X, Shekiro J, Elander R, Tucker M. Improved Xylan Hydrolysis of Corn Stover by Deacetylation with High Solids Dilute Acid Pretreatment. Ind Eng Chem Res 2011. [DOI: 10.1021/ie201493g] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaowen Chen
- National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, United States
| | - Joseph Shekiro
- National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, United States
| | - Rick Elander
- National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, United States
| | - Melvin Tucker
- National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, United States
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Zhang K, Agrawal M, Harper J, Chen R, Koros WJ. Removal of the Fermentation Inhibitor, Furfural, Using Activated Carbon in Cellulosic-Ethanol Production. Ind Eng Chem Res 2011. [DOI: 10.1021/ie2013983] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kuang Zhang
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, Georgia 30332-0100, United States
| | - Manoj Agrawal
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, Georgia 30332-0100, United States
| | - Justin Harper
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, Georgia 30332-0100, United States
| | - Rachel Chen
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, Georgia 30332-0100, United States
| | - William J. Koros
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 778 Atlantic Drive, Atlanta, Georgia 30332-0100, United States
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Nam HG, Jo SH, Mun S. Comparison of Amberchrom-CG161C and Dowex99 as the adsorbent of a four-zone simulated moving bed process for removal of acetic acid from biomass hydrolyzate. Process Biochem 2011. [DOI: 10.1016/j.procbio.2011.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jennings EW, Schell DJ. Conditioning of dilute-acid pretreated corn stover hydrolysate liquors by treatment with lime or ammonium hydroxide to improve conversion of sugars to ethanol. BIORESOURCE TECHNOLOGY 2011; 102:1240-5. [PMID: 20801647 DOI: 10.1016/j.biortech.2010.08.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 08/04/2010] [Accepted: 08/06/2010] [Indexed: 05/03/2023]
Abstract
Dilute-acid pretreatment of lignocellulosic biomass enhances the ability of enzymes to hydrolyze cellulose to glucose, but produces many toxic compounds that inhibit fermentation of sugars to ethanol. The objective of this study was to compare the effectiveness of treating hydrolysate liquor with Ca(OH)2 and NH4OH for improving ethanol yields. Corn stover was pretreated in a pilot-scale reactor and then the liquor fraction (hydrolysate) was extracted and treated with various amounts of Ca(OH)2 or NH4OH at several temperatures. Glucose and xylose in the treated liquor were fermented to ethanol using a glucose-xylose fermenting bacteria, Zymomonas mobilis 8b. Sugar losses up to 10% occurred during treatment with Ca(OH)2, but these losses were two to fourfold lower with NH4OH treatment. Ethanol yields for NH4OH-treated hydrolysate were 33% greater than those achieved in Ca(OH)2-treated hydrolysate and pH adjustment to either 6.0 or 8.5 with NH4OH prior to fermentation produced equivalent ethanol yields.
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Affiliation(s)
- Edward W Jennings
- National Bioenergy Center, National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, United States.
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Pérez-Carrillo E, Luisa Cortés-Callejas M, Sabillón-Galeas LE, Montalvo-Villarreal JL, Canizo JR, Georgina Moreno-Zepeda M, Serna-Saldivar SO. Detrimental effect of increasing sugar concentrations on ethanol production from maize or decorticated sorghum mashes fermented with Saccharomyces cerevisiae or Zymomonas mobilis. Biotechnol Lett 2010; 33:301-7. [DOI: 10.1007/s10529-010-0448-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 10/11/2010] [Indexed: 10/18/2022]
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Paradigm for industrial strain improvement identifies sodium acetate tolerance loci in Zymomonas mobilis and Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2010; 107:10395-400. [PMID: 20484677 DOI: 10.1073/pnas.0914506107] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The application of systems biology tools holds promise for rational industrial microbial strain development. Here, we characterize a Zymomonas mobilis mutant (AcR) demonstrating sodium acetate tolerance that has potential importance in biofuel development. The genome changes associated with AcR are determined using microarray comparative genome sequencing (CGS) and 454-pyrosequencing. Sanger sequencing analysis is employed to validate genomic differences and to investigate CGS and 454-pyrosequencing limitations. Transcriptomics, genetic data and growth studies indicate that over-expression of the sodium-proton antiporter gene nhaA confers the elevated AcR sodium acetate tolerance phenotype. nhaA over-expression mostly confers enhanced sodium (Na(+)) tolerance and not acetate (Ac(-)) tolerance, unless both ions are present in sufficient quantities. NaAc is more inhibitory than potassium and ammonium acetate for Z. mobilis and the combination of elevated Na(+) and Ac(-) ions exerts a synergistic inhibitory effect for strain ZM4. A structural model for the NhaA sodium-proton antiporter is constructed to provide mechanistic insights. We demonstrate that Saccharomyces cerevisiae sodium-proton antiporter genes also contribute to sodium acetate, potassium acetate, and ammonium acetate tolerances. The present combination of classical and systems biology tools is a paradigm for accelerated industrial strain improvement and combines benefits of few a priori assumptions with detailed, rapid, mechanistic studies.
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Yang S, Pelletier DA, Lu TYS, Brown SD. The Zymomonas mobilis regulator hfq contributes to tolerance against multiple lignocellulosic pretreatment inhibitors. BMC Microbiol 2010; 10:135. [PMID: 20459639 PMCID: PMC2877685 DOI: 10.1186/1471-2180-10-135] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 05/07/2010] [Indexed: 11/29/2022] Open
Abstract
Background Zymomonas mobilis produces near theoretical yields of ethanol and recombinant strains are candidate industrial microorganisms. To date, few studies have examined its responses to various stresses at the gene level. Hfq is a conserved bacterial member of the Sm-like family of RNA-binding proteins, coordinating a broad array of responses including multiple stress responses. In a previous study, we observed Z. mobilis ZM4 gene ZMO0347 showed higher expression under anaerobic, stationary phase compared to that of aerobic, stationary conditions. Results We generated a Z. mobilis hfq insertion mutant AcRIM0347 in an acetate tolerant strain (AcR) background and investigated its role in model lignocellulosic pretreatment inhibitors including acetate, vanillin, furfural and hydroxymethylfurfural (HMF). Saccharomyces cerevisiae Lsm protein (Hfq homologue) mutants and Lsm protein overexpression strains were also assayed for their inhibitor phenotypes. Our results indicated that all the pretreatment inhibitors tested in this study had a detrimental effect on both Z. mobilis and S. cerevisiae, and vanillin had the most inhibitory effect followed by furfural and then HMF for both Z. mobilis and S. cerevisiae. AcRIM0347 was more sensitive than the parental strain to the inhibitors and had an increased lag phase duration and/or slower growth depending upon the conditions. The hfq mutation in AcRIM0347 was complemented partially by trans-acting hfq gene expression. We also assayed growth phenotypes for S. cerevisiae Lsm protein mutant and overexpression phenotypes. Lsm1, 6, and 7 mutants showed reduced tolerance to acetate and other pretreatment inhibitors. S. cerevisiae Lsm protein overexpression strains showed increased acetate and HMF resistance as compared to the wild-type, while the overexpression strains showed greater inhibition under vanillin stress conditions. Conclusions We have shown the utility of the pKNOCK suicide plasmid for mutant construction in Z. mobilis, and constructed a Gateway compatible expression plasmid for use in Z. mobilis for the first time. We have also used genetics to show Z. mobilis Hfq and S. cerevisiae Lsm proteins play important roles in resisting multiple, important industrially relevant inhibitors. The conserved nature of this global regulator offers the potential to apply insights from these fundamental studies for further industrial strain development.
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Affiliation(s)
- Shihui Yang
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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40
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Abstract
The continuous cofermentation performance of xylose-fermenting Zymomonas mobilis at 30 degrees C and pH 5.5 was characterized using a pure-sugar feed solution that contained 8 g/L glucose and 40 g/L xylose. Successful chemostat start up resulted in complete utilization of glucose and greater than 85% utilization of xylose, but was only reproducibly achieved using initial dilution rates at or less than 0.04/h; once initiated, cofermentation could be maintained at dilution rates of 0.04 to 0.10/h. Whereas xylose and cell-mass concentrations increased gradually with increasing dilution rate, ethanol concentrations and ethanol yields on available sugars remained approximately constant at 20-22 g/L and 80-90% of theoretical, respectively. Volumetric and specific ethanol productivities increased linearly with increasing dilution rate, rising from approx 1.0 each (g/L/h or g/g/h) at a dilution rate of 0.04/h to approx 2.0 each (g/L/h or g/g/h) at a dilution rate of 0.10/h. Similarly, specific sugar-utilization rates increased from approx 2.0 g/g/h at dilution rate 0.04/h to approx 3.5 g/g/h at dilution rate of 0.10/h. The estimated values of 0.042 g/g for the maximum Z. mobilis cell-mass yield on substrate and 1.13 g/g/h for the minimum specific substrate utilization rate required for cellular maintenance energy are within the range of values reported in the literature. Results are also presented which suggest that long-term adaptation in continuous culture is a powerful technique for developing strains with higher tolerance to inhibitory hemicellulose hydrolyzates.
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Mills TY, Sandoval NR, Gill RT. Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS 2009; 2:26. [PMID: 19832972 PMCID: PMC2770041 DOI: 10.1186/1754-6834-2-26] [Citation(s) in RCA: 201] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 10/15/2009] [Indexed: 05/03/2023]
Abstract
The sustainable production of biofuels will require the efficient utilization of lignocellulosic biomass. A key barrier involves the creation of growth-inhibitory compounds by chemical pretreatment steps, which ultimately reduce the efficiency of fermentative microbial biocatalysts. The primary toxins include organic acids, furan derivatives, and phenolic compounds. Weak acids enter the cell and dissociate, resulting in a drop in intracellular pH as well as various anion-specific effects on metabolism. Furan derivatives, dehydration products of hexose and pentose sugars, have been shown to hinder fermentative enzyme function. Phenolic compounds, formed from lignin, can disrupt membranes and are hypothesized to interfere with the function of intracellular hydrophobic targets. This review covers mechanisms of toxicity and tolerance for these compounds with a specific focus on the important industrial organism Escherichia coli. Recent efforts to engineer E. coli for improved tolerance to these toxins are also discussed.
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Affiliation(s)
- Tirzah Y Mills
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Nicholas R Sandoval
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
| | - Ryan T Gill
- Department of Chemical and Biological Engineering, UCB424/ECCH120, University of Colorado, Boulder, CO 80309, USA
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Efficient degradation of lignocellulosic plant biomass, without pretreatment, by the thermophilic anaerobe "Anaerocellum thermophilum" DSM 6725. Appl Environ Microbiol 2009; 75:4762-9. [PMID: 19465524 DOI: 10.1128/aem.00236-09] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Very few cultivated microorganisms can degrade lignocellulosic biomass without chemical pretreatment. We show here that "Anaerocellum thermophilum" DSM 6725, an anaerobic bacterium that grows optimally at 75 degrees C, efficiently utilizes various types of untreated plant biomass, as well as crystalline cellulose and xylan. These include hardwoods such as poplar, low-lignin grasses such as napier and Bermuda grasses, and high-lignin grasses such as switchgrass. The organism did not utilize only the soluble fraction of the untreated biomass, since insoluble plant biomass (as well as cellulose and xylan) obtained after washing at 75 degrees C for 18 h also served as a growth substrate. The predominant end products from all growth substrates were hydrogen, acetate, and lactate. Glucose and cellobiose (on crystalline cellulose) and xylose and xylobiose (on xylan) also accumulated in the growth media during growth on the defined substrates but not during growth on the plant biomass. A. thermophilum DSM 6725 grew well on first- and second-spent biomass derived from poplar and switchgrass, where spent biomass is defined as the insoluble growth substrate recovered after the organism has reached late stationary phase. No evidence was found for the direct attachment of A. thermophilum DSM 6725 to the plant biomass. This organism differs from the closely related strain A. thermophilum Z-1320 in its ability to grow on xylose and pectin. Caldicellulosiruptor saccharolyticus DSM 8903 (optimum growth temperature, 70 degrees C), a close relative of A. thermophilum DSM 6725, grew well on switchgrass but not on poplar, indicating a significant difference in the biomass-degrading abilities of these two otherwise very similar organisms.
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Almeida JRM, Bertilsson M, Gorwa-Grauslund MF, Gorsich S, Lidén G. Metabolic effects of furaldehydes and impacts on biotechnological processes. Appl Microbiol Biotechnol 2009; 82:625-38. [PMID: 19184597 DOI: 10.1007/s00253-009-1875-1] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2008] [Revised: 01/13/2009] [Accepted: 01/14/2009] [Indexed: 11/30/2022]
Abstract
There is a growing awareness that lignocellulose will be a major raw material for production of both fuel and chemicals in the coming decades--most likely through various fermentation routes. Considerable attention has been given to the problem of finding efficient means of separating the major constituents in lignocellulose (i.e., lignin, hemicellulose, and cellulose) and to efficiently hydrolyze the carbohydrate parts into sugars. In these processes, by-products will inevitably form to some extent, and these will have to be dealt with in the ensuing microbial processes. One group of compounds in this category is the furaldehydes. 2-Furaldehyde (furfural) and substituted 2-furaldehydes--most importantly 5-hydroxymethyl-2-furaldehyde--are the dominant inhibitory compounds found in lignocellulosic hydrolyzates. The furaldehydes are known to have biological effects and act as inhibitors in fermentation processes. The effects of these compounds will therefore have to be considered in the design of biotechnological processes using lignocellulose. In this short review, we take a look at known metabolic effects, as well as strategies to overcome problems in biotechnological applications caused by furaldehydes.
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Affiliation(s)
- João R M Almeida
- Department of Applied Microbiology, Lund University, P.O. Box 124, 221 00 Lund, Sweden
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Rogers PL, Jeon YJ, Lee KJ, Lawford HG. Zymomonas mobilis for fuel ethanol and higher value products. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:263-88. [PMID: 17522816 DOI: 10.1007/10_2007_060] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
High oil prices, increasing focus on renewable carbohydrate-based feedstocks for fuels and chemicals, and the recent publication of its genome sequence, have provided continuing stimulus for studies on Zymomonas mobilis. However, despite its apparent advantages of higher yields and faster specific rates when compared to yeasts, no commercial scale fermentations currently exist which use Z. mobilis for the manufacture of fuel ethanol. This may change with the recent announcement of a Dupont/Broin partnership to develop a process for conversion of lignocellulosic residues, such as corn stover, to fuel ethanol using recombinant strains of Z. mobilis. The research leading to the construction of these strains, and their fermentation characteristics, are described in the present review. The review also addresses opportunities offered by Z. mobilis for higher value products through its metabolic engineering and use of specific high activity enzymes.
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Affiliation(s)
- P L Rogers
- School of Biotechnology and Biomolecular Sciences, UNSW, 2052 Sydney, Australia.
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45
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Conditioning hemicellulose hydrolysates for fermentation: Effects of overliming pH on sugar and ethanol yields. Process Biochem 2006. [DOI: 10.1016/j.procbio.2006.03.028] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Gutiérrez T, Ingram LO, Preston JF. Purification and characterization of a furfural reductase (FFR) from Escherichia coli strain LYO1—An enzyme important in the detoxification of furfural during ethanol production. J Biotechnol 2006; 121:154-64. [PMID: 16111779 DOI: 10.1016/j.jbiotec.2005.07.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 06/28/2005] [Accepted: 07/04/2005] [Indexed: 10/25/2022]
Abstract
Furfural, an inhibitor of ethanol production from hemicellulose acid hydrolysates, is reductively detoxified to furfuryl alcohol by the ethanologenic bacterium Escherichia coli strain LYO1. Furfural reductase was purified 106-fold from this bacterium to approximately 50% homogeneity. It has a native molecular mass of 135 kDa, determined by gel filtration, and subunit molecular mass of approximately 68 kDa, determined by denaturing gel electrophoresis, indicating the holoenzyme is a dimer of two similar if not identical subunits. The enzyme shows strong activity from pH 4 to 8 (optimum pH 7.0), relatively high temperature tolerance (50-55 degrees C), and an apparent Km and Vmax for furfural of 1.5x10(-4)M and 28.5 micromol/min/mg of protein, respectively. It catalyzes the essentially irreversible reduction of furfural with NADPH, is specific for NADPH as cofactor, and is relatively specific for the reduction of furfural and benzaldehyde; 2-acetylfuran, xylose, and glucose were not reduced, while acetaldehyde was reduced at a rate 25-fold lower than furfural. This is the first description of a furfural reductase which, based upon size and substrate specificity, appears to represent a new type of alcohol-aldehyde oxido-reductase. The conversion of relatively toxic furfural to less toxic furfuryl alcohol suggests a beneficial role for this enzyme in mitigating furfural toxicity encountered during ethanol production from lignocellulosic biomass.
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Affiliation(s)
- Tony Gutiérrez
- University of Florida, Institute of Food and Agricultural Science, Department of Microbiology and Cell Science, P.O. Box 110700, Gainesville, FL 32611-0700, USA
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Influence of strain and cultivation procedure on the performance of simultaneous saccharification and fermentation of steam pretreated spruce. Enzyme Microb Technol 2006. [DOI: 10.1016/j.enzmictec.2005.08.024] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Xie Y, Chin CY, Phelps DSC, Lee CH, Lee KB, Mun S, Wang NHL. A Five-Zone Simulated Moving Bed for the Isolation of Six Sugars from Biomass Hydrolyzate. Ind Eng Chem Res 2005. [DOI: 10.1021/ie050403d] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yi Xie
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Chim Yong Chin
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | | | - Chong-Ho Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Ki Bong Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Sungyong Mun
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Nien-Hwa Linda Wang
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
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Xie Y, Phelps D, Lee CH, Sedlak M, Ho N, Wang NHL. Comparison of Two Adsorbents for Sugar Recovery from Biomass Hydrolyzate. Ind Eng Chem Res 2005. [DOI: 10.1021/ie049079x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yi Xie
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Diana Phelps
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Chong-Ho Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Miroslav Sedlak
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Nancy Ho
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
| | - Nien-Hwa Linda Wang
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907
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50
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Delaquis P, Stanich K, Toivonen P. Effect of pH on the inhibition of Listeria spp. by vanillin and vanillic acid. J Food Prot 2005; 68:1472-6. [PMID: 16013390 DOI: 10.4315/0362-028x-68.7.1472] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The antimicrobial effects of vanillin and vanillic acid were verified against several species and strains of Listeria monocytogenes, Listeria innocua, Listeria grayi, and Listeria seeligeri in a laboratory medium adjusted to pH values ranging from 5.0 to 8.0. Medium pH had little influence on the MIC of vanillin as determined by a broth dilution assay, and growth of all test strains was inhibited by concentrations ranging from 23 to 33 mM. In contrast, none of the strains were inhibited by 100 mM vanillic acid at pH > 6.0, but complete inhibition was achieved at pH 5.0 with 10 mM. The effect of pH was further characterized by incubation of L. monocytogenes, L. innocua, and L. grayi in media containing 30 mM vanillin or 60 mM vanillic acid at pH 5.0, 6.0, and 7.0. Bactericidal effects increased with pH in media supplemented with vanillin. An inverse relationship was found for vanillic acid, and the lethality of the compound increased with declining pH. Mixtures of vanillin and vanillic acid exhibited additive inhibitory effects, particularly at lower pH. These natural antimicrobial compounds could prove useful either alone or in mixtures for the control of Listeria spp. in food products.
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Affiliation(s)
- Pascal Delaquis
- Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97 South, Summerland, British Columbia, Canada V0H 1Z0.
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