1
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Insights into cell robustness against lignocellulosic inhibitors and insoluble solids in bioethanol production processes. Sci Rep 2022; 12:557. [PMID: 35017613 PMCID: PMC8752620 DOI: 10.1038/s41598-021-04554-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 12/24/2021] [Indexed: 11/28/2022] Open
Abstract
Increasing yeast robustness against lignocellulosic-derived inhibitors and insoluble solids in bioethanol production is essential for the transition to a bio-based economy. This work evaluates the effect exerted by insoluble solids on yeast tolerance to inhibitory compounds, which is crucial in high gravity processes. Adaptive laboratory evolution (ALE) was applied on a xylose-fermenting Saccharomyces cerevisiae strain to simultaneously increase the tolerance to lignocellulosic inhibitors and insoluble solids. The evolved strain gave rise to a fivefold increase in bioethanol yield in fermentation experiments with high concentration of inhibitors and 10% (w/v) of water insoluble solids. This strain also produced 5% (P > 0.01) more ethanol than the parental in simultaneous saccharification and fermentation of steam-exploded wheat straw, mainly due to an increased xylose consumption. In response to the stress conditions (solids and inhibitors) imposed in ALE, cells induced the expression of genes related to cell wall integrity (SRL1, CWP2, WSC2 and WSC4) and general stress response (e.g., CDC5, DUN1, CTT1, GRE1), simultaneously repressing genes related to protein synthesis and iron transport and homeostasis (e.g., FTR1, ARN1, FRE1), ultimately leading to the improved phenotype. These results contribute towards understanding molecular mechanisms that cells might use to convert lignocellulosic substrates effectively.
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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: 53] [Impact Index Per Article: 17.7] [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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Jin J, Tao YT, Ding XB, Guo WP, Ruan L, Yang QL, Chen PC, Yao H, Zhang HB, Chen X. Predicted yeast interactome and network-based interpretation of transcriptionally changed genes. Yeast 2020; 37:573-583. [PMID: 32738156 DOI: 10.1002/yea.3516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 06/25/2020] [Accepted: 07/26/2020] [Indexed: 11/06/2022] Open
Abstract
Saccharomyces cerevisiae, budding yeast, is a widely used model organism and research tool in genetics studies. Many efforts have been directed at constructing a high-quality comprehensive molecular interaction network to elucidate the design logic of the gene circuitries in this classic model organism. In this work, we present the yeast interactome resource (YIR), which includes 22,238 putative functional gene interactions inferred from functional gene association data integrated from 10 databases focusing on diverse functional perspectives. These putative functional gene interactions are expected to cover 18.84% of yeast protein interactions, and 38.49% may represent protein interactions. Based on the YIR, a gene set linkage analysis (GSLA) web tool was developed to annotate the potential functional impacts of a set of transcriptionally changed genes. In a case study, we show that the YIR/GSLA system produced more extensive and concise annotations compared with widely used gene set annotation tools, including PANTHER and DAVID. Both YIR and GSLA are accessible through the website http://yeast.biomedtzc.cn.
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Affiliation(s)
- Jie Jin
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Yu-Tian Tao
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Xiao-Bao Ding
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Wen-Ping Guo
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Li Ruan
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Qiao-Lei Yang
- Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Peng-Cheng Chen
- Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Heng Yao
- Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou, China
| | - Hai-Bo Zhang
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China
| | - Xin Chen
- Institute of Big Data and Artificial Intelligence in Medicine, School of Electronics and Information Engineering, Taizhou University, Taizhou, China.,Institute of Pharmaceutical Biotechnology, School of Medicine, Zhejiang University, Hangzhou, China.,Joint Institute for Genetics and Genome Medicine, Zhejiang University and University of Toronto, Zhejiang University, Hangzhou, China
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4
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Abdou Alio M, Tugui OC, Rusu L, Pons A, Vial C. Hydrolysis and fermentation steps of a pretreated sawmill mixed feedstock for bioethanol production in a wood biorefinery. BIORESOURCE TECHNOLOGY 2020; 310:123412. [PMID: 32361645 DOI: 10.1016/j.biortech.2020.123412] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
The aim of this work was to demonstrate the feasibility of second-generation bioethanol production using for the first time a sawmill mixed feedstock comprising four softwood species, representative of biomass resource in Auvergne-Rhône-Alpes region (France). The feedstock was subjected to a microwave-assisted water/ethanol Organosolv pretreatment. The investigation focused on enzymatic hydrolysis of this pretreated sawmill feedstock (PSF) using Cellic® Ctec2 as the enzyme, followed by fermentation of the resulting sugar solution using Saccharomyces cerevisiae strain. The cellulose-rich PSF with 71% w/w cellulose content presented high saccharification yields (up to 80%), which made it perfect for subsequent fermentation; this yield was predicted vs. time up to 5.2% w/v PSF loading using a mathematical model fitted only on data at 1.5%. Finally, high PSF loading (7.5%) and scaleup were shown to impair the saccharification yield, but alcoholic fermentation could still be carried out up to 80% of the theoretical glucose-to-ethanol conversion yield.
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Affiliation(s)
- Maarouf Abdou Alio
- Université Clermont Auvergne, CNRS, Sigma Clermont, Institut Pascal, F-63000 Clermont-Ferrand, France
| | - Oana-Cristina Tugui
- University "Vasile Alecsandri" of Bacău, Faculty of Engineering, Chemical and Food Engineering Department, Bacău, Romania
| | - Lacramioara Rusu
- University "Vasile Alecsandri" of Bacău, Faculty of Engineering, Chemical and Food Engineering Department, Bacău, Romania
| | - Agnès Pons
- Université Clermont Auvergne, CNRS, Sigma Clermont, Institut Pascal, F-63000 Clermont-Ferrand, France
| | - Christophe Vial
- Université Clermont Auvergne, CNRS, Sigma Clermont, Institut Pascal, F-63000 Clermont-Ferrand, France.
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5
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Fan M, Li J, Bi G, Ye G, Zhang H, Xie J. Enhanced co-generation of cellulosic ethanol and methane with the starch/sugar-rich waste mixtures and Tween 80 in fed-batch mode. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:227. [PMID: 31572494 PMCID: PMC6757364 DOI: 10.1186/s13068-019-1562-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 09/07/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND The mixed-feedstock fermentation is a promising approach to enhancing the co-generation of cellulosic ethanol and methane from sugarcane bagasse (SCB) and molasses. However, the unmatched supply of the SCB and molasses remains a main obstacle built upon binary feedstock. Here, we propose a cellulose-starch-sugar ternary waste combinatory approach to overcome this bottleneck by integrating the starch-rich waste of Dioscorea composita Hemls. extracted residue (DER) in mixed fermentation. RESULTS The substrates of the pretreated SCB, DER and molasses with varying ratios were conducted at a relatively low solids loading of 12%, and the optimal mixture ratio of 1:0.5:0.5 for the pretreated SCB/DER/molasses was determined by evaluating the ethanol concentration and yield. Nevertheless, it was found that the ethanol yield decreased from 79.19 ± 0.20 to 62.31 ± 0.61% when the solids loading increased from 12 to 44% in batch modes, regardless of the fact that the co-fermentation of three-component feedstock was performed under the optimal condition defined above. Hence, different fermentation processes such as fed-batch and fed-batch + Tween 80 were implemented to further improve the ethanol concentration and yield at higher solids loading ranging between 36 and 44%. The highest ethanol concentration of 91.82 ± 0.86 g/L (69.33 ± 0.46% of theoretical yield) was obtained with fed-batch + Tween 80 mode during the simultaneous saccharification and fermentation at a high solids loading of 44%. Moreover, after the ethanol recovery, the remaining stillage was digested for biomethane production and finally yielded 320.72 ± 6.98 mL/g of volatile solids. CONCLUSIONS Integrated DER into the combination of SCB and molasses would be beneficial for ethanol production. The co-generation of bioethanol and biomethane by mixed cellulose-starch-sugar waste turns out to be a sustainable solution to improve the overall efficacy in biorefinery.
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Affiliation(s)
- Meishan Fan
- College of Forestry and Landscape Architecture, Guangdong Engineering Technology Research Center of Agricultural and Forestry Biomass, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, 510642 China
| | - Jun Li
- School of International Relations, Sun Yat-sen University, Guangzhou, China
| | - Guican Bi
- College of Forestry and Landscape Architecture, Guangdong Engineering Technology Research Center of Agricultural and Forestry Biomass, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, 510642 China
| | - Guangying Ye
- College of Forestry and Landscape Architecture, Guangdong Engineering Technology Research Center of Agricultural and Forestry Biomass, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, 510642 China
| | - Hongdan Zhang
- College of Forestry and Landscape Architecture, Guangdong Engineering Technology Research Center of Agricultural and Forestry Biomass, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, 510642 China
| | - Jun Xie
- College of Forestry and Landscape Architecture, Guangdong Engineering Technology Research Center of Agricultural and Forestry Biomass, Key Laboratory of Energy Plants Resource and Utilization, Ministry of Agriculture and Rural Affairs, South China Agricultural University, Guangzhou, 510642 China
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6
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Moreno AD, González-Fernández C, Ballesteros M, Tomás-Pejó E. Insoluble solids at high concentrations repress yeast's response against stress and increase intracellular ROS levels. Sci Rep 2019; 9:12236. [PMID: 31439886 PMCID: PMC6706384 DOI: 10.1038/s41598-019-48733-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/09/2019] [Indexed: 11/09/2022] Open
Abstract
Lignocellulosic ethanol production requires high substrate concentrations for its cost-competitiveness. This implies the presence of high concentrations of insoluble solids (IS) at the initial stages of the process, which may limit the fermentation performance of the corresponding microorganism. The presence of 40-60% IS (w/w) resulted in lower glucose consumption rates and reduced ethanol volumetric productivities of Saccharomyces cerevisiae F12. Yeast cells exposed to IS exhibited a wrinkled cell surface and a reduced mean cell size due to cavity formation. In addition, the intracellular levels of reactive oxygen species (ROS) increased up to 40%. These ROS levels increased up to 70% when both lignocellulose-derived inhibitors and IS were simultaneously present. The general stress response mechanisms (e.g. DDR2, TPS1 or ZWF1 genes, trehalose and glycogen biosynthesis, and DNA repair mechanisms) were found repressed, and ROS formation could not be counteracted by the induction of the genes involved in repairing the oxidative damage such as glutathione, thioredoxin and methionine scavenging systems (e.g. CTA1, GRX4, MXR1, and TSA1; and the repression of cell cycle progression, CLN3). Overall, these results clearly show the role of IS as an important microbial stress factor that affect yeast cells at physical, physiological, and molecular levels.
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Affiliation(s)
- Antonio D Moreno
- CIEMAT, Department of Energy, Biofuels Unit, 28040, Madrid, Spain.
| | | | - Mercedes Ballesteros
- CIEMAT, Department of Energy, Biofuels Unit, 28040, Madrid, Spain
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935, Móstoles, Spain
| | - Elia Tomás-Pejó
- IMDEA Energy Institute, Biotechnological Processes Unit, 28935, Móstoles, Spain.
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7
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Kurambhatti CV, Kumar D, Rausch KD, Tumbleson ME, Singh V. Increasing ethanol yield through fiber conversion in corn dry grind process. BIORESOURCE TECHNOLOGY 2018; 270:742-745. [PMID: 30279100 DOI: 10.1016/j.biortech.2018.09.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/10/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
Conversion of corn fiber to ethanol in the dry grind process could increase ethanol yields, reduce downstream processing costs and improve overall process profitability. This work investigates the in-situ conversion of corn fiber into ethanol (cellulase addition during simultaneous saccharification and fermentation) during dry grind process. Addition of 30 FPU/g fiber cellulase resulted in 4.6% increase in ethanol yield compared to the conventional process. Use of excess cellulase (120 FPU/g fiber) resulted in incomplete fermentation and lower ethanol yield compared to the conventional process. Multiple factors including high concentrations of ethanol and phenolic compounds were responsible for yeast stress and incomplete fermentation in excess cellulase experiments.
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Affiliation(s)
- Chinmay V Kurambhatti
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Deepak Kumar
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Kent D Rausch
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - M E Tumbleson
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Vijay Singh
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
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8
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Mithra MG, Jeeva ML, Sajeev MS, Padmaja G. Comparison of ethanol yield from pretreated lignocellulo-starch biomass under fed-batch SHF or SSF modes. Heliyon 2018; 4:e00885. [PMID: 30417150 PMCID: PMC6218405 DOI: 10.1016/j.heliyon.2018.e00885] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/07/2018] [Accepted: 10/23/2018] [Indexed: 11/02/2022] Open
Abstract
The ethanol yields from lignocellulo-starch biomass (peels of sweet potato, elephant foot yam, tannia, greater yam and beet root) by fed-batch separate hydrolysis and fermentation (F-SHF) and simultaneous saccharification and fermentation (F-SSF) using Saccharomyces cerevisiae were compared. Fed-batch saccharification of steam or dilute sulphuric acid pretreated biomass enhanced the reducing sugar yield which resulted in high RS consumption, volumetric ethanol productivity and ethanol yield during the first 24 h fermentation under F-SHF mode, while continuous production and utilization of reducing sugars occurred up to 72 h in F-SSF. Dilute sulphuric acid pretreated residues under F-SHF gave higher ethanol yield (34-43 g/L) and productivity (274-346 ml/kg dry biomass) than steam pretreatment (27-36 g/L and 223-295 ml/kg respectively), while F-SSF was superior for steam pretreated peels of sweet potato, elephant foot yam and tannia giving ethanol yields from 281 to 302 ml/kg. Glucose and xylose were present in all the hydrolysates with a preponderance of glucose and fermentation resulted in significant reduction in glucose levels in both F-SHF and F-SSF. Higher levels of total soluble phenolics and hydroxymethyl furfural were observed in the hydrolysates from dilute sulphuric acid pretreatment and yeast assimilated/detoxified part of the inhibitors, while only trivial amounts of furfural were present due to the low xylose content in the hydrolysates. Continuous formation led to higher accumulation of inhibitors in F-SSF despite supplementation with the detoxification mix comprising Tween 20, polyethylene glycol and sodium borohydride. F-SHF of dilute sulphuric acid pretreated biomass could be considered as a comparatively advantageous process where only one time feeding of enzyme cocktail and yeast was adopted compared to multiple feeds of enzymes and yeast along with other additives such as detoxification mix or nutrient solution in F-SSF.
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Affiliation(s)
- M G Mithra
- Division of Crop Utilization, ICAR- Central Tuber Crops Research Institute, Thiruvananthapuram 695 017, Kerala, India
| | - M L Jeeva
- Division of Crop Protection, ICAR- Central Tuber Crops Research Institute, Thiruvananthapuram 695 017, Kerala, India
| | - M S Sajeev
- Division of Crop Utilization, ICAR- Central Tuber Crops Research Institute, Thiruvananthapuram 695 017, Kerala, India
| | - G Padmaja
- Division of Crop Utilization, ICAR- Central Tuber Crops Research Institute, Thiruvananthapuram 695 017, Kerala, India
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9
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Ethanol Production from Corn Fiber Separated after Liquefaction in the Dry Grind Process. ENERGIES 2018. [DOI: 10.3390/en11112921] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Conversion of corn fiber to ethanol in the dry grind process can increase ethanol yields, improve coproduct quality and contribute to process sustainability. This work investigates the use of two physio-chemical pretreatments on corn fiber and effect of cellulase enzyme dosage to improve ethanol yields. Fiber separated after liquefaction of corn was pretreated using (I) hot water pretreatment (160 °C for 5, 10 or 20 min) and (II) wet disk milling and converted to ethanol. The conversion efficiencies of hot water pretreated fiber were higher than untreated fiber, with highest increase in conversion (10.4%) achieved for 5 min residence time at 160 °C. Disk milling was not effective in increasing conversion compared to other treatments. Hydrolysis and fermentation of untreated fiber with excess cellulase enzymes resulted in 33.3% higher conversion compared to untreated fiber.
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10
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Yang P, Wu Y, Zheng Z, Cao L, Zhu X, Mu D, Jiang S. CRISPR-Cas9 Approach Constructing Cellulase sestc-Engineered Saccharomyces cerevisiae for the Production of Orange Peel Ethanol. Front Microbiol 2018; 9:2436. [PMID: 30364071 PMCID: PMC6191481 DOI: 10.3389/fmicb.2018.02436] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 09/24/2018] [Indexed: 11/25/2022] Open
Abstract
The development of lignocellulosic bioethanol plays an important role in the substitution of petrochemical energy and high-value utilization of agricultural wastes. The safe and stable expression of cellulase gene sestc was achieved by applying the clustered regularly interspaced short palindromic repeats-Cas9 approach to the integration of sestc expression cassette containing Agaricus biporus glyceraldehyde-3-phosphate-dehydrogenase gene (gpd) promoter in the Saccharomyces cerevisiae chromosome. The target insertion site was found to be located in the S. cerevisiae hexokinase 2 by designing a gRNA expression vector. The recombinant SESTC protein exhibited a size of approximately 44 kDa in the engineered S. cerevisiae. By using orange peel as the fermentation substrate, the filter paper, endo-1,4-β-glucanase, exo-1,4-β-glucanase activities of the transformants were 1.06, 337.42, and 1.36 U/mL, which were 35.3-fold, 23.03-fold, and 17-fold higher than those from wild-type S. cerevisiae, respectively. After 6 h treatment, approximately 20 g/L glucose was obtained. Under anaerobic conditions the highest ethanol concentration reached 7.53 g/L after 48 h fermentation and was 37.7-fold higher than that of wild-type S. cerevisiae (0.2 g/L). The engineered strains may provide a valuable material for the development of lignocellulosic ethanol.
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Affiliation(s)
- Peizhou Yang
- College of Food and Biological Engineering, Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, China
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11
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Lee CR, Sung BH, Lim KM, Kim MJ, Sohn MJ, Bae JH, Sohn JH. Co-fermentation using Recombinant Saccharomyces cerevisiae Yeast Strains Hyper-secreting Different Cellulases for the Production of Cellulosic Bioethanol. Sci Rep 2017; 7:4428. [PMID: 28667330 PMCID: PMC5493647 DOI: 10.1038/s41598-017-04815-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 05/19/2017] [Indexed: 01/02/2023] Open
Abstract
To realize the economical production of ethanol and other bio-based chemicals from lignocellulosic biomass by consolidated bioprocessing (CBP), various cellulases from different sources were tested to improve the level of cellulase secretion in the yeast Saccharomyces cerevisiae by screening an optimal translational fusion partner (TFP) as both a secretion signal and fusion partner. Among them, four indispensable cellulases for cellulose hydrolysis, including Chaetomium thermophilum cellobiohydrolase (CtCBH1), Chrysosporium lucknowense cellobiohydrolase (ClCBH2), Trichoderma reesei endoglucanase (TrEGL2), and Saccharomycopsis fibuligera β-glucosidase (SfBGL1), were identified to be highly secreted in active form in yeast. Despite variability in the enzyme levels produced, each recombinant yeast could secrete approximately 0.6–2.0 g/L of cellulases into the fermentation broth. The synergistic effect of the mixed culture of the four strains expressing the essential cellulases with the insoluble substrate Avicel and several types of cellulosic biomass was demonstrated to be effective. Co-fermentation of these yeast strains produced approximately 14 g/L ethanol from the pre-treated rice straw containing 35 g/L glucan with 3-fold higher productivity than that of wild type yeast using a reduced amount of commercial cellulases. This process will contribute to the cost-effective production of bioenergy such as bioethanol and biochemicals from cellulosic biomass.
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Affiliation(s)
- Cho-Ryong Lee
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.,Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Bong Hyun Sung
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea.,Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113, Republic of Korea
| | - Kwang-Mook Lim
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Mi-Jin Kim
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Min Jeong Sohn
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Jung-Hoon Bae
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea
| | - Jung-Hoon Sohn
- Cell Factory Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, 34141, Republic of Korea. .,Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, Korea University of Science and Technology (UST), Daejeon, 34113, Republic of Korea.
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12
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Aftab MN, Zafar A, Awan AR. Expression of thermostable β-xylosidase in Escherichia coli for use in saccharification of plant biomass. Bioengineered 2017; 8:665-669. [PMID: 28140759 DOI: 10.1080/21655979.2016.1267884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The present work is aimed to evaluate the saccharification potential of a thermostable β-xylosidase cloned from Bacillus licheniformis into Escherichia coli for production of bioethanol from plant biomass. Recombinant β-xylosidase enzyme possesses the ability of bioconversion of plant biomass like wheat straw, rice straw and sugarcane bagass. By using this approach, plant biomass that mainly constitute cellulose can be converted to reducing sugars that could then be easily converted to bioethanol by simple fermentation process. The production of bioethanol will help to overcome energy requirements due to depleting fossil fuels and will also help to protect environment by reducing greenhouse gas emission. In the end, future directions are briefly mentioned that can be utilized to reduce the cost and increase the yield of biofuels.
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Affiliation(s)
- Muhammad N Aftab
- a Institute of Industrial Biotechnology, Government College University , Katchery Road, Lahore , Pakistan
| | - Asma Zafar
- a Institute of Industrial Biotechnology, Government College University , Katchery Road, Lahore , Pakistan
| | - Ali R Awan
- b Institute of Biochemistry & Biotechnology, University of Veterinary and Animal Sciences , Lahore , Pakistan
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13
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Olofsson J, Barta Z, Börjesson P, Wallberg O. Integrating enzyme fermentation in lignocellulosic ethanol production: life-cycle assessment and techno-economic analysis. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:51. [PMID: 28250818 PMCID: PMC5324314 DOI: 10.1186/s13068-017-0733-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/11/2017] [Indexed: 05/05/2023]
Abstract
BACKGROUND Cellulase enzymes have been reported to contribute with a significant share of the total costs and greenhouse gas emissions of lignocellulosic ethanol production today. A potential future alternative to purchasing enzymes from an off-site manufacturer is to integrate enzyme and ethanol production, using microorganisms and part of the lignocellulosic material as feedstock for enzymes. This study modelled two such integrated process designs for ethanol from logging residues from spruce production, and compared it to an off-site case based on existing data regarding purchased enzymes. Greenhouse gas emissions and primary energy balances were studied in a life-cycle assessment, and cost performance in a techno-economic analysis. RESULTS The base case scenario suggests that greenhouse gas emissions per MJ of ethanol could be significantly lower in the integrated cases than in the off-site case. However, the difference between the integrated and off-site cases is reduced with alternative assumptions regarding enzyme dosage and the environmental impact of the purchased enzymes. The comparison of primary energy balances did not show any significant difference between the cases. The minimum ethanol selling price, to reach break-even costs, was from 0.568 to 0.622 EUR L-1 for the integrated cases, as compared to 0.581 EUR L-1 for the off-site case. CONCLUSIONS An integrated process design could reduce greenhouse gas emissions from lignocellulose-based ethanol production, and the cost of an integrated process could be comparable to purchasing enzymes produced off-site. This study focused on the environmental and economic assessment of an integrated process, and in order to strengthen the comparison to the off-site case, more detailed and updated data regarding industrial off-site enzyme production are especially important.
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Affiliation(s)
- Johanna Olofsson
- Division of Environmental and Energy Systems Studies, Department of Technology and Society, Lund University, John Ericssons väg 1, 22363 Lund, Sweden
| | - Zsolt Barta
- Department of Applied Biotechnology and Food Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Muegyetem rkp. 3, Budapest, 1111 Hungary
| | - Pål Börjesson
- Division of Environmental and Energy Systems Studies, Department of Technology and Society, Lund University, John Ericssons väg 1, 22363 Lund, Sweden
| | - Ola Wallberg
- Department of Chemical Engineering, Lund University, Naturvetarvägen 14, 22362 Lund, Sweden
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Bondesson PM, Galbe M. Process design of SSCF for ethanol production from steam-pretreated, acetic-acid-impregnated wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:222. [PMID: 27777624 PMCID: PMC5070003 DOI: 10.1186/s13068-016-0635-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 10/07/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Pretreatment is an important step in the production of ethanol from lignocellulosic material. Using acetic acid together with steam pretreatment allows the positive effects of an acid catalyst to be retained, while avoiding the negative environmental effects associated with sulphuric acid. Acetic acid is also formed during the pretreatment and hydrolysis of hemicellulose, and is a known inhibitor that may impair fermentation at high concentrations. The purpose of this study was to improve ethanol production from glucose and xylose in steam-pretreated, acetic-acid-impregnated wheat straw by process design of simultaneous saccharification and co-fermentation (SSCF), using a genetically modified pentose fermenting yeast strain Saccharomyces cerevisiae. RESULTS Ethanol was produced from glucose and xylose using both the liquid fraction and the whole slurry from pretreated materials. The highest ethanol concentration achieved was 37.5 g/L, corresponding to an overall ethanol yield of 0.32 g/g based on the glucose and xylose available in the pretreated material. To obtain this concentration, a slurry with a water-insoluble solids (WIS) content of 11.7 % was used, using a fed-batch SSCF strategy. A higher overall ethanol yield (0.36 g/g) was obtained at 10 % WIS. CONCLUSIONS Ethanol production from steam-pretreated, acetic-acid-impregnated wheat straw through SSCF with a pentose fermenting S. cerevisiae strain was successfully demonstrated. However, the ethanol concentration was too low and the residence time too long to be suitable for large-scale applications. It is hoped that further process design focusing on the enzymatic conversion of cellulose to glucose will allow the combination of acetic acid pretreatment and co-fermentation of glucose and xylose.
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Affiliation(s)
- Pia-Maria Bondesson
- Department of Chemical Engineering, Lund University, P.O. Box 124, 221 00 Lund, Sweden
| | - Mats Galbe
- Department of Chemical Engineering, Lund University, P.O. Box 124, 221 00 Lund, Sweden
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15
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Fumaric Acid Production from Alkali-Pretreated Corncob by Fed-Batch Simultaneous Saccharification and Fermentation Combined with Separated Hydrolysis and Fermentation at High Solids Loading. Appl Biochem Biotechnol 2016; 181:573-583. [DOI: 10.1007/s12010-016-2232-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 08/29/2016] [Indexed: 10/21/2022]
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16
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Paulova L, Patakova P, Branska B, Rychtera M, Melzoch K. Lignocellulosic ethanol: Technology design and its impact on process efficiency. Biotechnol Adv 2015; 33:1091-107. [DOI: 10.1016/j.biotechadv.2014.12.002] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/01/2014] [Accepted: 12/03/2014] [Indexed: 12/27/2022]
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17
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Tabah B, Pulidindi IN, Chitturi VR, Arava LMR, Gedanken A. Solar-Energy Driven Simultaneous Saccharification and Fermentation of Starch to Bioethanol for Fuel-Cell Applications. CHEMSUSCHEM 2015; 8:3497-3503. [PMID: 26350032 DOI: 10.1002/cssc.201500469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 07/12/2015] [Indexed: 06/05/2023]
Abstract
A solar reactor was designed to perform the conversion of starch to ethanol in a single step. An aqueous starch solution (5 wt %) was fed into the reactor bed charged with Baker's yeast (Saccharomyces cerevisiae) and amylase, resulting in approximately 2.5 wt % ethanol collected daily (ca. 25 mL day(-1) ). A significant amount of ethanol (38 g) was collected over 63 days, corresponding to 84 % of the theoretical yield. The production of ethanol without additional energy input highlights the significance of this new process. The ethanol produced was also demonstrated as a potential fuel for direct ethanol fuel cells. Additionally, the secondary metabolite glycerol was fully reduced to a value-added product 1,3-propanediol, which is the first example of a fungal strain (Baker's yeast) converting glycerol in situ to 1,3-propanediol.
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Affiliation(s)
- Betina Tabah
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | | | | | | | - Aharon Gedanken
- Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52900, Israel.
- Department of Materials Science and Engineering, National Cheng Kung University, Tainan, 70101, Taiwan.
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18
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New biofuel alternatives: integrating waste management and single cell oil production. Int J Mol Sci 2015; 16:9385-405. [PMID: 25918941 PMCID: PMC4463594 DOI: 10.3390/ijms16059385] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 02/26/2015] [Accepted: 04/14/2015] [Indexed: 11/29/2022] Open
Abstract
Concerns about greenhouse gas emissions have increased research efforts into alternatives in bio-based processes. With regard to transport fuel, bioethanol and biodiesel are still the main biofuels used. It is expected that future production of these biofuels will be based on processes using either non-food competing biomasses, or characterised by low CO2 emissions. Many microorganisms, such as microalgae, yeast, bacteria and fungi, have the ability to accumulate oils under special culture conditions. Microbial oils might become one of the potential feed-stocks for biodiesel production in the near future. The use of these oils is currently under extensive research in order to reduce production costs associated with the fermentation process, which is a crucial factor to increase economic feasibility. An important way to reduce processing costs is the use of wastes as carbon sources. The aim of the present review is to describe the main aspects related to the use of different oleaginous microorganisms for lipid production and their performance when using bio-wastes. The possibilities for combining hydrogen (H2) and lipid production are also explored in an attempt for improving the economic feasibility of the process.
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Romero I, López-Linares JC, Delgado Y, Cara C, Castro E. Ethanol production from rape straw by a two-stage pretreatment under mild conditions. Bioprocess Biosyst Eng 2015; 38:1469-78. [DOI: 10.1007/s00449-015-1389-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 03/17/2015] [Indexed: 11/24/2022]
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20
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Rana V, Eckard AD, Ahring BK. Comparison of SHF and SSF of wet exploded corn stover and loblolly pine using in-house enzymes produced from T. reesei RUT C30 and A. saccharolyticus. SPRINGERPLUS 2014; 3:516. [PMID: 25279308 PMCID: PMC4176844 DOI: 10.1186/2193-1801-3-516] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 08/27/2014] [Indexed: 11/10/2022]
Abstract
The aim of the present study was to compare bioethanol production from wet exploded corn stover (WECS) and loblolly pine (WELP) hydrolyzed with in-house and commercial enzymes and fermented separately (SHF) and simultaneously (SSF). In-house enzymes produced from Trichoderma reesei, RUT-C30 and a novel fungal strain, Aspergillus saccharolyticus were loaded as 5 and 15 FPU/g glucan and supplemented with 10 and 30 CBU/g glucan, respectively. For hydrolysis and fermentation, slurries of WECS and WELP at 5 and 10% (w/w) solids loading (SL) were utilized. Saccharomyces cerevisae was used for ethanol fermentation at 33°C. Maximally, 15.6 g/L and 13.4 g/L (corresponding to theoretical ethanol yield of 76% and 67%, respectively) were achieved in SSF process from WECS and WELP, respectively at 5% SL and 15 FPU/g glucan loading of in-house enzymes. Ethanol concentrations in all cases were higher for SSF compared to SHF under same conditions. A cross comparison of SSF with commercial enzymes (Celluclast 1.5 L + Novozym 188) showed highest ethanol concentration of 17.3 g/L and 15.4 g/L (corresponding to theoretical ethanol yield of 84% and 77%, respectively) from WECS and WELP, respectively at 5% SL and 15 FPU/g glucan. These findings demonstrated that in-house enzymes were comparable to commercial enzymes as these fungi produced other lignocellulolytic enzymes beyond cellulase and hence enhanced the overall enzyme activity.
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Affiliation(s)
- Vandana Rana
- Bioproducts, Sciences and Engineering Laboratory (BSEL), Washington State University, 2710 Crimson Way, Richland, WA 99354-1671 USA
| | - Anahita D Eckard
- Bioproducts, Sciences and Engineering Laboratory (BSEL), Washington State University, 2710 Crimson Way, Richland, WA 99354-1671 USA
| | - Birgitte K Ahring
- Bioproducts, Sciences and Engineering Laboratory (BSEL), Washington State University, 2710 Crimson Way, Richland, WA 99354-1671 USA
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Kawaguchi H, Uematsu K, Ogino C, Teramura H, Niimi-Nakamura S, Tsuge Y, Hasunuma T, Oinuma KI, Takaya N, Kondo A. Simultaneous saccharification and fermentation of kraft pulp by recombinant Escherichia coli for phenyllactic acid production. Biochem Eng J 2014. [DOI: 10.1016/j.bej.2014.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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22
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Cao GL, Zhao L, Wang AJ, Wang ZY, Ren NQ. Single-step bioconversion of lignocellulose to hydrogen using novel moderately thermophilic bacteria. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:82. [PMID: 24920960 PMCID: PMC4052809 DOI: 10.1186/1754-6834-7-82] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/16/2014] [Indexed: 05/10/2023]
Abstract
BACKGROUND Consolidated bioprocessing (CBP) of lignocellulosic biomass to hydrogen offers great potential for lower cost and higher efficiency compared to processes featuring dedicated cellulase production. Current studies on CBP-based hydrogen production mainly focus on using the thermophilic cellulolytic bacterium Clostridium thermocellum and the extremely thermophilic cellulolytic bacterium Caldicellulosiruptor saccharolyticus. However, no studies have demonstrated that the strains in the genus Thermoanaerobacterium could be used as the sole microorganism to accomplish both cellulose degradation and H2 generation. RESULTS We have specifically screened for moderately thermophilic cellulolytic bacteria enabling to produce hydrogen directly from conversion of lignocellulosic materials. Three new strains of thermophilic cellulolytic bacteria in the genus Thermoanaerobacterium growing at a temperature of 60°C were isolated. All of them grew well on various plant polymers including microcrystalline cellulose, filter paper, xylan, glucose, and xylose. In particular, the isolated bacterium, designated as Thermoanaerobacterium thermosaccharolyticum M18, showed high cellulolytic activity and a high yield of H2. When it was grown in 0.5% microcrystalline cellulose, approximately 82% cellulose was consumed, and the H2 yield and maximum production rate reached 10.86 mmol/g Avicel and 2.05 mmol/L/h, respectively. Natural lignocellulosic materials without any physicochemical or biological pretreatment also supported appreciable growth of strain M18, which resulted in 56.07% to 62.71% of insoluble cellulose and hemicellulose polymer degradation in corn cob, corn stalk, and wheat straw with a yield of 3.23 to 3.48 mmol H2/g substrate and an average production rate of 0.10 to 0.13 mmol H2/L/h. CONCLUSIONS The newly isolated strain T. thermosaccharolyticum M18 displayed effective degradation of lignocellulose and produced large amounts of hydrogen. This is the first report of a Thermoanaerobacterium species presenting cellulolytic characteristics, and this species thus represents a novel cellulolytic bacterium distinguished from all other known cellulolytic bacteria. In comparison, the extraordinary yield and specific rate of hydrogen for strain M18 obtained from lignocellulose make it more attractive in monoculture fermentation. T. thermosaccharolyticum M18 is thus a potential candidate for rapid conversion of lignocellulose to biohydrogen in a single step.
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Affiliation(s)
- Guang-Li Cao
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150090, China
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Lei Zhao
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Ai-Jie Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Zhen-Yu Wang
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150090, China
| | - Nan-Qi Ren
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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Ethanol from laccase-detoxified lignocellulose by the thermotolerant yeast Kluyveromyces marxianus—Effects of steam pretreatment conditions, process configurations and substrate loadings. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2013.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Zhao L, Cao GL, Wang AJ, Guo WQ, Ren HY, Ren NQ. Simultaneous saccharification and fermentation of fungal pretreated cornstalk for hydrogen production using Thermoanaerobacterium thermosaccharolyticum W16. BIORESOURCE TECHNOLOGY 2013; 145:103-107. [PMID: 23489570 DOI: 10.1016/j.biortech.2013.01.144] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 06/01/2023]
Abstract
In this research, environmentally friendly fungal pretreatment was first adopted for deconstruction of cornstalk. Then the fungal-pretreated cornstalk was employed to produce hydrogen in simultaneous saccharification and fermentation (SSF) using crude enzyme from Trichoderma viride and Thermoanaerobacterium thermosaccharolyticum W16. The influence of various factors including substrate concentration, initial pH, and enzyme loading on hydrogen production were evaluated. The highest hydrogen yield of 89.3 ml/g-cornstalk was obtained with an initial pH 6.5, 0.75% substrate concentration, and 34 FPU/g cellulose. Compared the result with SSF of physical or chemical pretreated lignocellulosic materials, this research suggested an economic and efficient way for hydrogen production from lignocellulosic biomass.
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Affiliation(s)
- Lei Zhao
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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25
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Gaikwad A, Chakraborty S. Mixing Effects on the Kinetics of Enzymatic Hydrolysis of Avicel for Batch Production of Cellulosic Ethanol. Ind Eng Chem Res 2013. [DOI: 10.1021/ie301234b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ashwin Gaikwad
- Department of Chemical
Engineering, Indian Institute of Technology − Kharagpur, Kharagpur
721302, India
| | - Saikat Chakraborty
- Department of Chemical
Engineering, Indian Institute of Technology − Kharagpur, Kharagpur
721302, India
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26
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Production and Partial Characterization of Cellulases and Xylanases from Trichoderma atroviride 676 Using Lignocellulosic Residual Biomass. Appl Biochem Biotechnol 2013; 169:1373-85. [DOI: 10.1007/s12010-012-0053-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 12/26/2012] [Indexed: 10/27/2022]
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Bhatia L, Johri S, Ahmad R. An economic and ecological perspective of ethanol production from renewable agro waste: a review. AMB Express 2012; 2:65. [PMID: 23217124 PMCID: PMC3547755 DOI: 10.1186/2191-0855-2-65] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 11/26/2012] [Indexed: 11/11/2022] Open
Abstract
Agro-industrial wastes are generated during the industrial processing of agricultural products. These wastes are generated in large amounts throughout the year, and are the most abundant renewable resources on earth. Due to the large availability and composition rich in compounds that could be used in other processes, there is a great interest on the reuse of these wastes, both from economical and environmental view points. The economic aspect is based on the fact that such wastes may be used as low-cost raw materials for the production of other value-added compounds, with the expectancy of reducing the production costs. The environmental concern is because most of the agro-industrial wastes contain phenolic compounds and/or other compounds of toxic potential; which may cause deterioration of the environment when the waste is discharged to the nature. Although the production of bioethanol offers many benefits, more research is needed in the aspects like feedstock preparation, fermentation technology modification, etc., to make bioethanol more economically viable.
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Consolidated bioprocessing and simultaneous saccharification and fermentation of lignocellulose to ethanol with thermotolerant yeast strains. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.05.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Albers E, Johansson E, Franzén CJ, Larsson C. Selective suppression of bacterial contaminants by process conditions during lignocellulose based yeast fermentations. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:59. [PMID: 22185398 PMCID: PMC3284421 DOI: 10.1186/1754-6834-4-59] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/20/2011] [Indexed: 05/21/2023]
Abstract
BACKGROUND Contamination of bacteria in large-scale yeast fermentations is a serious problem and a threat to the development of successful biofuel production plants. Huge research efforts have been spent in order to solve this problem, but additional ways must still be found to keep bacterial contaminants from thriving in these environments. The aim of this project was to develop process conditions that would inhibit bacterial growth while giving yeast a competitive advantage. RESULTS Lactic acid bacteria are usually considered to be the most common contaminants in industrial yeast fermentations. Our observations support this view but also suggest that acetic acid bacteria, although not so numerous, could be a much more problematic obstacle to overcome. Acetic acid bacteria showed a capacity to drastically reduce the viability of yeast. In addition, they consumed the previously formed ethanol. Lactic acid bacteria did not show this detrimental effect on yeast viability. It was possible to combat both types of bacteria by a combined addition of NaCl and ethanol to the wood hydrolysate medium used. As a result of NaCl + ethanol additions the amount of viable bacteria decreased and yeast viability was enhanced concomitantly with an increase in ethanol concentration. The successful result obtained via addition of NaCl and ethanol was also confirmed in a real industrial ethanol production plant with its natural inherent yeast/bacterial community. CONCLUSIONS It is possible to reduce the number of bacteria and offer a selective advantage to yeast by a combined addition of NaCl and ethanol when cultivated in lignocellulosic medium such as wood hydrolysate. However, for optimal results, the concentrations of NaCl + ethanol must be adjusted to suit the challenges offered by each hydrolysate.
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Affiliation(s)
- Eva Albers
- Department Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Emma Johansson
- Department Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Processum Biorefinery Initiative, 891 80 Örnsköldsvik, Sweden
| | - Carl Johan Franzén
- Department Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Christer Larsson
- Department Chemical and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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Optimization of saccharification and ethanol production by simultaneous saccharification and fermentation (SSF) from seaweed, Saccharina japonica. Bioprocess Biosyst Eng 2011; 35:11-8. [DOI: 10.1007/s00449-011-0611-2] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 07/21/2011] [Indexed: 11/26/2022]
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Andrade JP, Bispo ASDR, Marbach PAS, do Nascimento RP. Production and Partial Characterization of Cellulases from Trichoderma sp. IS-05 Isolated from Sandy Coastal Plains of Northeast Brazil. Enzyme Res 2011; 2011:167248. [PMID: 21904668 PMCID: PMC3163401 DOI: 10.4061/2011/167248] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 05/30/2011] [Accepted: 06/29/2011] [Indexed: 11/22/2022] Open
Abstract
This study evaluated the production of cellulolytic enzymes by Trichoderma sp. IS-05 strain, isolated from sand dunes, according to its ability to grow on cellulose as carbon source. Wheat bran was tested as the carbon source and peptone tested as the nitrogen source. Different concentrations of carbon and nitrogen were tested using a factorial design to identify optimal cellulase activity production. The results showed that media containing wheat bran 4.0% (w/v) and peptone 0.25% (w/v) lead to the highest production, 564.0 U L−1 of cellulase, obtained after 2 days of fermentation. The pH and temperature profile showed optimal activity at pH 3.0 and 60°C. As for thermostability, the cellulase was most tolerant at 60°C, retaining more than 59.6% of maximal activity even after 4 hours of incubation. The combination of acid pH, high temperature tolerance, and production of cellulase from agro-industrial residues by Trichoderma sp. IS-05 offers possibilities condition for the biomass hydrolysis process to produce bioethanol.
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Affiliation(s)
- Jackeline Pereira Andrade
- Centro de Ciências Agrárias, Ambientais e Biológicas (CCAAB), Universidade Federal do Recôncavo da Bahia (UFRB), 44380-000 Cruz das Almas, BA, Brazil
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Tang Y, Zhao D, Cristhian C, Jiang J. Simultaneous saccharification and cofermentation of lignocellulosic residues from commercial furfural production and corn kernels using different nutrient media. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:22. [PMID: 21801455 PMCID: PMC3161845 DOI: 10.1186/1754-6834-4-22] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 07/31/2011] [Indexed: 05/15/2023]
Abstract
BACKGROUND As the supply of starch grain and sugar cane, currently the main feedstocks for bioethanol production, become limited, lignocelluloses will be sought as alternative materials for bioethanol production. Production of cellulosic ethanol is still cost-inefficient because of the low final ethanol concentration and the addition of nutrients. We report the use of simultaneous saccharification and cofermentation (SSCF) of lignocellulosic residues from commercial furfural production (furfural residue, FR) and corn kernels to compare different nutritional media. The final ethanol concentration, yield, number of live yeast cells, and yeast-cell death ratio were investigated to evaluate the effectiveness of integrating cellulosic and starch ethanol. RESULTS Both the ethanol yield and number of live yeast cells increased with increasing corn-kernel concentration, whereas the yeast-cell death ratio decreased in SSCF of FR and corn kernels. An ethanol concentration of 73.1 g/L at 120 h, which corresponded to a 101.1% ethanol yield based on FR cellulose and corn starch, was obtained in SSCF of 7.5% FR and 14.5% corn kernels with mineral-salt medium. SSCF could simultaneously convert cellulose into ethanol from both corn kernels and FR, and SSCF ethanol yield was similar between the organic and mineral-salt media. CONCLUSIONS Starch ethanol promotes cellulosic ethanol by providing important nutrients for fermentative organisms, and in turn cellulosic ethanol promotes starch ethanol by providing cellulosic enzymes that convert the cellulosic polysaccharides in starch materials into additional ethanol. It is feasible to produce ethanol in SSCF of FR and corn kernels with mineral-salt medium. It would be cost-efficient to produce ethanol in SSCF of high concentrations of water-insoluble solids of lignocellulosic materials and corn kernels. Compared with prehydrolysis and fed-batch strategy using lignocellulosic materials, addition of starch hydrolysates to cellulosic ethanol production is a more suitable method to improve the final ethanol concentration.
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Affiliation(s)
- Yong Tang
- Department of Chemistry and Chemical Engineering, Beijing Forestry University, Beijing, China
| | - Danqing Zhao
- Department of Chemistry and Chemical Engineering, Beijing Forestry University, Beijing, China
| | - Carrasco Cristhian
- Department of Chemical Engineering, Lund University, P.O. Box 124, 221 00, Lund, Sweden
| | - Jianxin Jiang
- Department of Chemistry and Chemical Engineering, Beijing Forestry University, Beijing, China
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Simultaneous saccharification and fermentation of furfural residues by mixed cultures of lactic acid bacteria and yeast to produce lactic acid and ethanol. Eur Food Res Technol 2011. [DOI: 10.1007/s00217-011-1542-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Shen F, Zhong Y, Saddler JN, Liu R. Relatively High-Substrate Consistency Hydrolysis of Steam-Pretreated Sweet Sorghum Bagasse at Relatively Low Cellulase Loading. Appl Biochem Biotechnol 2011; 165:1024-36. [DOI: 10.1007/s12010-011-9317-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 06/19/2011] [Indexed: 11/28/2022]
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35
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Asyraf Kas M, Abu Bakar N, Soh Kheang L, Aziz A. Influence of Solid Loading Concentrations, Inoculums Size and Nitrogen Sources on Ethanol Production from Empty Fruit Bunches (EFB) Hydrolysate in Separate Hydrolysis and Fermentation (SHF). ACTA ACUST UNITED AC 2011. [DOI: 10.3923/rjasci.2011.310.319] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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36
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Yu H, Zhang X, Song L, Ke J, Xu C, Du W, Zhang J. Evaluation of white-rot fungi-assisted alkaline/oxidative pretreatment of corn straw undergoing enzymatic hydrolysis by cellulase. J Biosci Bioeng 2010; 110:660-4. [DOI: 10.1016/j.jbiosc.2010.08.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 08/02/2010] [Accepted: 08/03/2010] [Indexed: 11/27/2022]
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37
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Hakola M, Kallioinen A, Kemell M, Lahtinen P, Lankinen E, Leskelä M, Repo T, Riekkola T, Siika-aho M, Uusitalo J, Vuorela S, von Weymarn N. Liberation of cellulose from the lignin cage: A catalytic pretreatment method for the production of cellulosic ethanol. CHEMSUSCHEM 2010; 3:1142-5. [PMID: 20853392 DOI: 10.1002/cssc.201000217] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Affiliation(s)
- Maija Hakola
- Department of Chemistry, University of Helsinki, P.O. Box 55, 00014 Helsinki, Finland
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Kumar L, Chandra R, Chung PA, Saddler J. Can the same steam pretreatment conditions be used for most softwoods to achieve good, enzymatic hydrolysis and sugar yields? BIORESOURCE TECHNOLOGY 2010; 101:7827-33. [PMID: 20570139 DOI: 10.1016/j.biortech.2010.05.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 05/07/2023]
Abstract
Wood chips from six different Douglas-fir trees and a representative Lodgepole pine were steam pretreated at a single pretreatment condition (200 °C 4% SO₂ 5 min) which had previously been shown to be effective for Spruce and Lodgepole pine chips. All of the softwood samples responded in a similar fashion with more than 60% of the cellulose hydrolysed after 72 h, at an enzyme loading of 20 FPU/g cellulose. However, when the enzyme loading was reduced to 5FPU, less than 27% of the cellulose was hydrolysed. When the steam pretreated substrates were subsequently delignified they were almost completely hydrolysed, at both high, 20 FPU/g cellulose (less than 12 h) and low, 5 FPU/g (within 72 h) enzyme loadings. Although optimized steam pretreatment could result in greater than 90% glucose recovery, in order to obtain complete hydrolysis of the cellulosic component at reduced enzyme loadings a delignification step will likely be required.
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Affiliation(s)
- Linoj Kumar
- Forest Products Biotechnology/Bioenergy Group, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada V6T 1Z4
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39
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Barta Z, Kovacs K, Reczey K, Zacchi G. Process design and economics of on-site cellulase production on various carbon sources in a softwood-based ethanol plant. Enzyme Res 2010; 2010:734182. [PMID: 21048869 PMCID: PMC2962911 DOI: 10.4061/2010/734182] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 03/29/2010] [Indexed: 11/20/2022] Open
Abstract
On-site cellulase enzyme fermentation in a softwood-to-ethanol process, based on SO(2)-catalysed steam pretreatment followed by simultaneous saccharification and fermentation, was investigated from a techno-economic aspect using Aspen Plus© and Aspen Icarus Process Evaluator© softwares. The effect of varying the carbon source of enzyme fermentation, at constant protein and mycelium yields, was monitored through the whole process. Enzyme production step decreased the overall ethanol yield (270 L/dry tonne of raw material in the case of purchased enzymes) by 5-16 L/tonne. Capital cost was found to be the main cost contributor to enzyme fermentation, constituting to 60-78% of the enzyme production cost, which was in the range of 0.42-0.53 SEK/L ethanol. The lowest minimum ethanol selling prices (4.71 and 4.82 SEK/L) were obtained in those scenarios, where pretreated liquid fraction supplemented with molasses was used as carbon source. In some scenarios, on-site enzyme fermentation was found to be a feasible alternative.
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Affiliation(s)
- Zsolt Barta
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Szt. Gellért tér 4, 1111 Budapest, Hungary
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40
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Hoyer K, Galbe M, Zacchi G. Effects of enzyme feeding strategy on ethanol yield in fed-batch simultaneous saccharification and fermentation of spruce at high dry matter. BIOTECHNOLOGY FOR BIOFUELS 2010; 3:14. [PMID: 20579340 PMCID: PMC2908074 DOI: 10.1186/1754-6834-3-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 06/25/2010] [Indexed: 05/08/2023]
Abstract
BACKGROUND To make lignocellulosic fuel ethanol economically competitive with fossil fuels, it is necessary to reduce the production cost. One way to achieve this is by increasing the substrate concentration in the production process, and thus reduce the energy demand in the final distillation of the fermentation broth. However, increased substrate concentration in simultaneous saccharification and fermentation (SSF) processes has been shown to result in reduced ethanol yields and severe stirring problems. Because the SSF medium is being continuously hydrolyzed, running the process in fed-batch mode could potentially reduce the stirring problems and lead to increased ethanol yields in high-solids SSF. Different enzyme feeding strategies, with the enzymes either present in the reactor from start-up or fed into the reactor together with the substrate, have been studied, along with the influence of the enzyme feeding strategy on the final ethanol yield and productivity. RESULTS In the present study, SSF was run successfully with 10% and 14% water-insoluble solids (WIS) in batch and fed-batch mode. The mixing of the material in the reactor was significantly better in fed-batch than batch mode, and similarly high or higher ethanol yields were achieved in fed-batch mode compared with batch SSF in some cases. No general trend in the dependence of ethanol yield on enzyme feeding strategy was found. CONCLUSIONS The optimum enzyme feeding strategy appears to depend on the conditions during SSF, such as the WIS concentration and the concentration of inhibitory compounds in the SSF medium.
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Affiliation(s)
- Kerstin Hoyer
- Department of Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden
| | - Mats Galbe
- Department of Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden
| | - Guido Zacchi
- Department of Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden
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Zhang X, Qin W, Paice MG, Saddler JN. High consistency enzymatic hydrolysis of hardwood substrates. BIORESOURCE TECHNOLOGY 2009; 100:5890-7. [PMID: 19643602 DOI: 10.1016/j.biortech.2009.06.082] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 05/01/2009] [Accepted: 06/20/2009] [Indexed: 05/09/2023]
Abstract
The feasibility of using a laboratory peg mixer to carry out high consistency enzymatic hydrolysis of lignocellulosic substrates was investigated. Two hardwood substrates, unbleached hardwood pulp (UBHW) and organosolv pretreated poplar (OPP), were used in this study. Hydrolysis of UBHW and OPP at 20% substrate consistency led to a high glucose concentration in the final hydrolysate. For example, a 48 h enzymatic hydrolysis of OPP resulted in a hydrolysate with 158 g/L of glucose. This is the highest glucose concentration ever obtained from enzymatic hydrolysis of lignocellulosic substrates. Fermentation of UBHW and OPP hydrolysates with high glucose content led to high ethanol concentrations, 50.4 and 63.1 g/L, respectively after fermentation. Our results demonstrate that using common pulping equipment to carry out high consistency hydrolysis can overcome the rheological problems and greatly increase the sugar and ethanol concentrations after the hydrolysis and fermentation.
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Affiliation(s)
- Xiao Zhang
- FPInnovations Paprican Division (PAPRICAN), 570 boul. St-Jean, Pointe-Claire, Quebec, Canada H9R 3J9.
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42
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Kovács K, Szakács G, Zacchi G. Enzymatic hydrolysis and simultaneous saccharification and fermentation of steam-pretreated spruce using crude Trichoderma reesei and Trichoderma atroviride enzymes. Process Biochem 2009. [DOI: 10.1016/j.procbio.2009.07.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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43
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Bansal P, Hall M, Realff MJ, Lee JH, Bommarius AS. Modeling cellulase kinetics on lignocellulosic substrates. Biotechnol Adv 2009; 27:833-848. [DOI: 10.1016/j.biotechadv.2009.06.005] [Citation(s) in RCA: 302] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 06/19/2009] [Accepted: 06/20/2009] [Indexed: 11/15/2022]
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44
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Dashtban M, Schraft H, Qin W. Fungal bioconversion of lignocellulosic residues; opportunities & perspectives. Int J Biol Sci 2009; 5:578-95. [PMID: 19774110 PMCID: PMC2748470 DOI: 10.7150/ijbs.5.578] [Citation(s) in RCA: 324] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 08/02/2009] [Indexed: 11/28/2022] Open
Abstract
The development of alternative energy technology is critically important because of the rising prices of crude oil, security issues regarding the oil supply, and environmental issues such as global warming and air pollution. Bioconversion of biomass has significant advantages over other alternative energy strategies because biomass is the most abundant and also the most renewable biomaterial on our planet. Bioconversion of lignocellulosic residues is initiated primarily by microorganisms such as fungi and bacteria which are capable of degrading lignocellulolytic materials. Fungi such as Trichoderma reesei and Aspergillus niger produce large amounts of extracellular cellulolytic enzymes, whereas bacterial and a few anaerobic fungal strains mostly produce cellulolytic enzymes in a complex called cellulosome, which is associated with the cell wall. In filamentous fungi, cellulolytic enzymes including endoglucanases, cellobiohydrolases (exoglucanases) and beta-glucosidases work efficiently on cellulolytic residues in a synergistic manner. In addition to cellulolytic/hemicellulolytic activities, higher fungi such as basidiomycetes (e.g. Phanerochaete chrysosporium) have unique oxidative systems which together with ligninolytic enzymes are responsible for lignocellulose degradation. This review gives an overview of different fungal lignocellulolytic enzymatic systems including extracellular and cellulosome-associated in aerobic and anaerobic fungi, respectively. In addition, oxidative lignocellulose-degradation mechanisms of higher fungi are discussed. Moreover, this paper reviews the current status of the technology for bioconversion of biomass by fungi, with focus on mutagenesis, co-culturing and heterologous gene expression attempts to improve fungal lignocellulolytic activities to create robust fungal strains.
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Affiliation(s)
- Mehdi Dashtban
- 1. Biorefining Research Initiative, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, Canada, P7B 5E1
- 2. Department of Biology, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, Canada, P7B 5E1
| | - Heidi Schraft
- 2. Department of Biology, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, Canada, P7B 5E1
| | - Wensheng Qin
- 1. Biorefining Research Initiative, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, Canada, P7B 5E1
- 2. Department of Biology, Lakehead University, 955 Oliver Rd, Thunder Bay, Ontario, Canada, P7B 5E1
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45
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Drissen RET, Maas RHW, Tramper J, Beeftink HH. Modelling ethanol production from cellulose: separate hydrolysis and fermentation versus simultaneous saccharification and fermentation. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420802564358] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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46
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Kovács K, Szakacs G, Zacchi G. Comparative enzymatic hydrolysis of pretreated spruce by supernatants, whole fermentation broths and washed mycelia of Trichoderma reesei and Trichoderma atroviride. BIORESOURCE TECHNOLOGY 2009; 100:1350-7. [PMID: 18793835 DOI: 10.1016/j.biortech.2008.08.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 08/05/2008] [Accepted: 08/06/2008] [Indexed: 05/02/2023]
Abstract
Cellulase and beta-glucosidase production on steam pretreated spruce (SPS) with Trichoderma reesei Rut C30, Trichoderma atroviride TUB F-1505 and TUB F-1663 was investigated. The enzymes were compared in term of activity, temperature optima and hydrolytic capacity. The T. atroviride cellulases proved to have lower temperature optima for filter paper activity (FPA) assay (50 degrees C) and for hydrolysis of SPS (40 degrees C) than the Rut C30 enzymes (60 degrees C for FPA and 50 degrees C for hydrolysis). Due to high levels of extracellular beta-glucosidases, the T. atroviride enzyme supernatants hydrolyzed the washed SPS to glucose more efficiently than the enzymes produced by T. reesei. On the other hand, when the whole fermentation broths were used instead of the supernatants, thus the mycelium bound enzymes were also present, the hydrolytic capacity of T. reesei Rut C30 was enhanced by approximately 200%, while an improvement of only 15% was observed in case of the T. atroviride isolates.
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Affiliation(s)
- Krisztina Kovács
- Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, Budapest, Gellért tér 4, Hungary
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47
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Tomás-Pejó E, García-Aparicio M, Negro MJ, Oliva JM, Ballesteros M. Effect of different cellulase dosages on cell viability and ethanol production by Kluyveromyces marxianus in SSF processes. BIORESOURCE TECHNOLOGY 2009; 100:890-5. [PMID: 18722114 DOI: 10.1016/j.biortech.2008.07.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 07/03/2008] [Accepted: 07/12/2008] [Indexed: 05/23/2023]
Abstract
This study was aimed to study the effect of commercial cellulases (Celluclast 1.5 LFG) on Kluyveromyces marxianus CECT 10875 growth and ethanol production in SSF processes. Preliminary tests carried out in glucose (50 g/L) fermentation medium showed that high enzyme amounts (2.5-3.5 FPU/mL) could cause a negative effect on K. marxianus growth rate and viable cells number. However, the maximum ethanol production was not affected and about 86% of the theoretical (22 g/L) was reached in all cases independently of the enzyme dosage. In SSF experiments, cell viability was always affected by enzyme loading. Nevertheless, slight differences observed on cell viability during glucose fermentation processes with the detected concentrations of the additives did not justify the negative effect observed in SSF experiments.
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Affiliation(s)
- E Tomás-Pejó
- Renewable Energies Department-CIEMAT, Avda. Complutense, 22 28040-Madrid, Spain.
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48
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Sánchez OJ, Cardona CA. Trends in biotechnological production of fuel ethanol from different feedstocks. BIORESOURCE TECHNOLOGY 2008; 99:5270-95. [PMID: 18158236 DOI: 10.1016/j.biortech.2007.11.013] [Citation(s) in RCA: 616] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2006] [Revised: 11/04/2007] [Accepted: 11/06/2007] [Indexed: 05/02/2023]
Abstract
Present work deals with the biotechnological production of fuel ethanol from different raw materials. The different technologies for producing fuel ethanol from sucrose-containing feedstocks (mainly sugar cane), starchy materials and lignocellulosic biomass are described along with the major research trends for improving them. The complexity of the biomass processing is recognized through the analysis of the different stages involved in the conversion of lignocellulosic complex into fermentable sugars. The features of fermentation processes for the three groups of studied feedstocks are discussed. Comparative indexes for the three major types of feedstocks for fuel ethanol production are presented. Finally, some concluding considerations on current research and future tendencies in the production of fuel ethanol regarding the pretreatment and biological conversion of the feedstocks are presented.
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Affiliation(s)
- Oscar J Sánchez
- Department of Chemical Engineering, National University of Colombia at Manizales, Cra. 27 No. 64-60 Of. F-505, Manizales, Caldas, Colombia
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49
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Lau MW, Dale BE, Balan V. Ethanolic fermentation of hydrolysates from ammonia fiber expansion (AFEX) treated corn stover and distillers grain without detoxification and external nutrient supplementation. Biotechnol Bioeng 2008; 99:529-39. [PMID: 17705225 DOI: 10.1002/bit.21609] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
External nutrient supplementation and detoxification of hydrolysate significantly increase the production cost of cellulosic ethanol. In this study, we investigated the feasibility of fermenting cellulosic hydrolysates without washing, detoxification or external nutrient supplementation using ethanologens Escherichia coli KO11 and the adapted strain ML01 at low initial cell density (16 mg dry weight/L). The cellulosic hydrolysates were derived from enzymatically digested ammonia fiber expansion (AFEX)-treated corn stover and dry distiller's grain and solubles (DDGS) at high solids loading (18% by weight). The adaptation was achieved through selective evolution of KO11 on hydrolysate from AFEX-treated corn stover. All cellulosic hydrolysates tested (36-52 g/L glucose) were fermentable. Regardless of strains, metabolic ethanol yields were near the theoretical limit (0.51 g ethanol/g consumed sugar). Volumetric ethanol productivity of 1.2 g/h/L was achieved in fermentation on DDGS hydrolysate and DDGS improved the fermentability of hydrolysate from corn stover. However, enzymatic hydrolysis and xylose utilization during fermentation were the bottlenecks for ethanol production from corn stover at these experimental conditions. In conclusion, fermentation under the baseline conditions was feasible. Utilization of nutrient-rich feedstocks such as DDGS in fermentation can replace expensive media supplementation.
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Affiliation(s)
- Ming W Lau
- Biomass Conversion Research Lab (BCRL), Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA.
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50
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Olofsson K, Rudolf A, Lidén G. Designing simultaneous saccharification and fermentation for improved xylose conversion by a recombinant strain of Saccharomyces cerevisiae. J Biotechnol 2008; 134:112-20. [PMID: 18294716 DOI: 10.1016/j.jbiotec.2008.01.004] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 12/06/2007] [Accepted: 01/08/2008] [Indexed: 10/22/2022]
Abstract
Wheat straw is an abundant agricultural residue which can be used as a raw material for bioethanol production. Due to the high xylan content in wheat straw, fermentation of both xylose and glucose is crucial to meet desired overall yields of ethanol. In the present work a recombinant xylose fermenting strain of Saccharomyces cerevisiae, TMB3400, cultivated aerobically on wheat straw hydrolysate, was used in simultaneous saccharification and fermentation (SSF) of steam pretreated wheat straw. The influence of fermentation strategy and temperature was studied in relation to xylose consumption, ethanol formation and by-product formation. In addition, model SSF experiments were made to further investigate the influence of temperature on xylose fermentation and by-product formation. In particular for SSF at the highest value of fibre content tested (9% water insoluble substance, WIS), it was found that a fed-batch strategy was clearly superior to the batch process in terms of ethanol yield, where the fed-batch gave 71% of the theoretical yield (based on all available sugars) in comparison to merely 59% for the batch. Higher ethanol yields, close to 80%, were obtained at a WIS-content of 7%. Xylose fermentation significantly contributed to the overall ethanol yields. The choice of temperature in the range 30-37 degrees C was found to be important, especially at higher contents of water insoluble solids (WIS). The optimum temperature was found to be 34 degrees C for the raw material and yeast strain studied. Model SSF experiments with defined medium showed strong temperature effects on the xylose uptake rate and xylitol yield.
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Affiliation(s)
- Kim Olofsson
- Department of Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden.
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