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Jarboe LR, Khalid A, Ocasio ER, Fashkami KN. Extrapolation of design strategies for lignocellulosic biomass conversion to the challenge of plastic waste. J Ind Microbiol Biotechnol 2022; 49:6510821. [PMID: 35040946 PMCID: PMC9119000 DOI: 10.1093/jimb/kuac001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/18/2022] [Indexed: 11/12/2022]
Abstract
The goal of cost-effective production of fuels and chemicals from biomass has been a substantial driver of the development of the field of Metabolic Engineering. The resulting design principles and procedures provide a guide for the development of cost-effective methods for degradation, and possibly even valorization, of plastic wastes. Here we highlight these parallels, using the creative work of Lonnie O'Neal (Neal) Ingram in enabling production of fuels and chemicals from lignocellulosic biomass, with a focus on ethanol production as an exemplar process.
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Affiliation(s)
- Laura R Jarboe
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Ammara Khalid
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Efrain Rodriguez Ocasio
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
| | - Kimia Noroozi Fashkami
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA
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2
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Consolidated bio-saccharification: Leading lignocellulose bioconversion into the real world. Biotechnol Adv 2020; 40:107535. [DOI: 10.1016/j.biotechadv.2020.107535] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/03/2020] [Accepted: 02/12/2020] [Indexed: 11/22/2022]
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3
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Moraïs S, Shterzer N, Lamed R, Bayer EA, Mizrahi I. A combined cell-consortium approach for lignocellulose degradation by specialized Lactobacillus plantarum cells. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:112. [PMID: 25788977 PMCID: PMC4364503 DOI: 10.1186/1754-6834-7-112] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 07/09/2014] [Indexed: 05/28/2023]
Abstract
BACKGROUND Lactobacillus plantarum is an attractive candidate for metabolic engineering towards bioprocessing of lignocellulosic biomass to ethanol or polylactic acid, as its natural characteristics include high ethanol and acid tolerance and the ability to metabolize the two major polysaccharide constituents of lignocellulolytic biomass (pentoses and hexoses). We recently engineered L. plantarum via separate introduction of a potent cellulase and xylanase, thereby creating two different L. plantarum strains. We used these strains as a combined cell-consortium for synergistic degradation of cellulosic biomass. RESULTS To optimize enzymatic degradation, we applied the cell-consortium approach to assess the significance of enzyme localization by comparing three enzymatic paradigms prevalent in nature: (i) a secreted enzymes system, (ii) enzymes anchored to the bacterial cell surface and (iii) enzymes integrated into cellulosome complexes. The construction of the three paradigmatic systems involved the division of the production and organization of the enzymes and scaffold proteins into different strains of L. plantarum. The spatial differentiation of the components of the enzymatic systems alleviated the load on the cell machinery of the different bacterial strains. Active designer cellulosomes containing a xylanase and a cellulase were thus assembled on L. plantarum cells by co-culturing three distinct engineered strains of the bacterium: two helper strains for enzyme secretion and one producing only the anchored scaffoldin. Alternatively, the two enzymes were anchored separately to the cell wall. The secreted enzyme consortium appeared to have a slight advantage over the designer cellulosome system in degrading the hypochlorite pretreated wheat straw substrate, and both exhibited significantly higher levels of activity compared to the anchored enzyme consortium. However, the secreted enzymes appeared to be less stable than the enzymes integrated into designer cellulosomes, suggesting an advantage of the latter over longer time periods. CONCLUSIONS By developing the potential of L. plantarum to express lignocellulolytic enzymes and to control their functional combination and stoichiometry on the cell wall, this study provides a step forward towards optimal biomass bioprocessing and soluble fermentable sugar production. Future expansion of the preferred secreted-enzyme and designer-cellulosome systems to include additional types of enzymes will promote enhanced deconstruction of cellulosic feedstocks.
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Affiliation(s)
- Sarah Moraïs
- />Department of Biological Chemistry, The Weizmann Institute of Science, 234 Herzl St, Rehovot, 7610001 Israel
| | - Naama Shterzer
- />Department of Ruminant Science, Institute of Animal Sciences, Agricultural Research Organization, P.O.B. 6, Bet-Dagan, 50250 Israel
| | - Raphael Lamed
- />Department of Molecular Microbiology and Biotechnology, Tel Aviv University, P.O. Box 39040, Ramat Aviv, 69978 Israel
| | - Edward A Bayer
- />Department of Biological Chemistry, The Weizmann Institute of Science, 234 Herzl St, Rehovot, 7610001 Israel
| | - Itzhak Mizrahi
- />Department of Ruminant Science, Institute of Animal Sciences, Agricultural Research Organization, P.O.B. 6, Bet-Dagan, 50250 Israel
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Nanofibrillated Cellulose (NFC): A High-Value Co-Product that Improves the Economics of Cellulosic Ethanol Production. ENERGIES 2014. [DOI: 10.3390/en7020607] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Establishment of a simple Lactobacillus plantarum cell consortium for cellulase-xylanase synergistic interactions. Appl Environ Microbiol 2013; 79:5242-9. [PMID: 23811500 DOI: 10.1128/aem.01211-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus plantarum is an attractive candidate for bioprocessing of lignocellulosic biomass due to its high metabolic variability, including its ability to ferment both pentoses and hexoses, as well as its high acid tolerance, a quality often utilized in industrial processes. This bacterium grows naturally on biomass; however, it lacks the inherent ability to deconstruct lignocellulosic substrates. As a first step toward engineering lignocellulose-converting lactobacilli, we have introduced genes coding for a GH6 cellulase and a GH11 xylanase from a highly active cellulolytic bacterium into L. plantarum. For this purpose, we employed the recently developed pSIP vectors for efficient secretion of heterologous proteins. Both enzymes were secreted by L. plantarum at levels estimated at 0.33 nM and 3.3 nM, for the cellulase and xylanase, respectively, in culture at an optical density at 600 nm (OD600) of 1. Transformed cells demonstrated the ability to degrade individually either cellulose or xylan and wheat straw. When mixed together to form a two-strain cell-based consortium secreting both cellulase and xylanase, they exhibited synergistic activity in the overall release of soluble sugar from wheat straw. This result paves the way toward metabolic harnessing of L. plantarum for novel biorefining applications, such as production of ethanol and polylactic acid directly from plant biomass.
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Yamada R, Hasunuma T, Kondo A. Endowing non-cellulolytic microorganisms with cellulolytic activity aiming for consolidated bioprocessing. Biotechnol Adv 2013; 31:754-63. [PMID: 23473971 DOI: 10.1016/j.biotechadv.2013.02.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/19/2013] [Accepted: 02/24/2013] [Indexed: 11/17/2022]
Abstract
With the exhaustion of fossil fuels and with the environmental issues they pose, utilization of abundant lignocellulosic biomass as a feedstock for biofuels and bio-based chemicals has recently become an attractive option. Lignocellulosic biomass is primarily composed of cellulose, hemicellulose, and lignin and has a very rigid and complex structure. It is accordingly much more expensive to process than starchy grains because of the need for extensive pretreatment and relatively large amounts of cellulases for efficient hydrolysis. Efficient and cost-effective methods for the production of biofuels and chemicals from lignocellulose are required. A consolidated bioprocess (CBP), which integrates all biological steps consisting of enzyme production, saccharification, and fermentation, is considered a promising strategy for reducing production costs. Establishing an efficient CBP using lignocellulosic biomass requires both lignocellulose degradation into glucose and efficient production of biofuels or chemicals from glucose. With this aim, many researchers are attempting to endow selected microorganisms with lignocellulose-assimilating ability. In this review, we focus on studies aimed at conferring lignocellulose-assimilating ability not only to yeast strains but also to bacterial strains by recombinant technology. Recent developments in improvement of enzyme productivity by microorganisms and in improvement of the specific activity of cellulase are emphasized.
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Affiliation(s)
- Ryosuke Yamada
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodaicho, Nada, Kobe 657-8501, Japan
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Periplasmic expression of a Saccharophagus cellodextrinase enables E. coli to ferment cellodextrin. Appl Microbiol Biotechnol 2013; 97:8129-38. [DOI: 10.1007/s00253-012-4646-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 12/05/2012] [Accepted: 12/09/2012] [Indexed: 11/27/2022]
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Zhao XH, Wang W, Wang FQ, Wei DZ. A comparative study of β-1, 4-endoglucanase (possessing β-1, 4-exoglucanase activity) from Bacillus subtilis LH expressed in Pichia pastoris GS115 and Escherichia coli Rosetta (DE3). BIORESOURCE TECHNOLOGY 2012; 110:539-545. [PMID: 22336741 DOI: 10.1016/j.biortech.2011.12.086] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 12/15/2011] [Accepted: 12/17/2011] [Indexed: 05/31/2023]
Abstract
β-1, 4-Endoglucanase (EG) from Bacillus subtilis LH was expressed in Escherichia coli Rosetta (DE3) and Pichia pastoris GS115, respectively. The CMCase activity of EG (EGE) from the cell lysate of DE3 reached 20,010U/ml, and that of EG (EGP) from the supernatant of GS115 was only 2008U/ml. EGE and EGP were bifunctional cellulases excluding β-1, 4-glucosidase (BGL). The CMCases of them, optimally active at 65°C and pH 6.8, exhibited more than 80% residual activity at pH 5-10 and 60% activity at 40-70°C and pH 5-9. EGE (EGP) mixed with BGL had more than 1.5-fold higher CMCase and filter paperase activities compared to EGE (EGP). N-glycosylation protected EGP from immobilized-papain attack and accounted for 30kDa and a higher thermostability, whereas EGE was decomposed into a 33kDa active truncated EG (EGT) and two 18kDa fragments. EGE and EGP performed much better than EGT in denim biostoning.
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Affiliation(s)
- Xi-Hua Zhao
- State Key Lab of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China
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9
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Creation of a cellooligosaccharide-assimilating Escherichia coli strain by displaying active beta-glucosidase on the cell surface via a novel anchor protein. Appl Environ Microbiol 2011; 77:6265-70. [PMID: 21742905 DOI: 10.1128/aem.00459-11] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We demonstrated direct assimilation of cellooligosaccharide using Escherichia coli displaying beta-glucosidase (BGL). BGL from Thermobifida fusca YX (Tfu0937) was displayed on the E. coli cell surface using a novel anchor protein named Blc. This strain was grown successfully on 0.2% cellobiose, and the optical density at 600 nm (OD(600)) was 1.05 after 20 h.
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van Zyl WH, Chimphango AFA, den Haan R, Görgens JF, Chirwa PWC. Next-generation cellulosic ethanol technologies and their contribution to a sustainable Africa. Interface Focus 2011; 1:196-211. [PMID: 22482027 PMCID: PMC3262263 DOI: 10.1098/rsfs.2010.0017] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 01/12/2011] [Indexed: 11/12/2022] Open
Abstract
The world is currently heavily dependent on oil, especially in the transport sector. However, rising oil prices, concern about environmental impact and supply instability are among the factors that have led to greater interest in renewable fuel and green chemistry alternatives. Lignocellulose is the only foreseeable renewable feedstock for sustainable production of transport fuels. The main technological impediment to more widespread utilization of lignocellulose for production of fuels and chemicals in the past has been the lack of low-cost technologies to overcome the recalcitrance of its structure. Both biological and thermochemical second-generation conversion technologies are currently coming online for the commercial production of cellulosic ethanol concomitantly with heat and electricity production. The latest advances in biological conversion of lignocellulosics to ethanol with a focus on consolidated bioprocessing are highlighted. Furthermore, integration of cellulosic ethanol production into existing bio-based industries also using thermochemical processes to optimize energy balances is discussed. Biofuels have played a pivotal yet suboptimal role in supplementing Africa's energy requirements in the past. Capitalizing on sub-Saharan Africa's total biomass potential and using second-generation technologies merit a fresh look at the potential role of bioethanol production towards developing a sustainable Africa while addressing food security, human needs and local wealth creation.
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Affiliation(s)
- W. H. van Zyl
- Department of Microbiology, University of Stellenbosch, De Beer Street, Stellenbosch 7600, South Africa
| | - A. F. A. Chimphango
- Department of Process Engineering, University of Stellenbosch, De Beer Street, Stellenbosch 7600, South Africa
| | - R. den Haan
- Department of Microbiology, University of Stellenbosch, De Beer Street, Stellenbosch 7600, South Africa
| | - J. F. Görgens
- Department of Process Engineering, University of Stellenbosch, De Beer Street, Stellenbosch 7600, South Africa
| | - P. W. C. Chirwa
- Forest Science Postgraduate Programme, University of Pretoria, Pretoria 0002, South Africa
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Zhang XZ, Zhang YHP. One-step production of biocommodities from lignocellulosic biomass by recombinant cellulolytic Bacillus subtilis: Opportunities and challenges. Eng Life Sci 2010. [DOI: 10.1002/elsc.201000011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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12
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la Grange DC, den Haan R, van Zyl WH. Engineering cellulolytic ability into bioprocessing organisms. Appl Microbiol Biotechnol 2010; 87:1195-208. [DOI: 10.1007/s00253-010-2660-x] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 05/02/2010] [Accepted: 05/02/2010] [Indexed: 10/19/2022]
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13
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Martin GJO, Knepper A, Zhou B, Pamment NB. Performance and stability of ethanologenic Escherichia coli strain FBR5 during continuous culture on xylose and glucose. J Ind Microbiol Biotechnol 2006; 33:834-44. [PMID: 16680457 DOI: 10.1007/s10295-006-0129-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Accepted: 04/03/2006] [Indexed: 10/24/2022]
Abstract
Escherichia coli FBR5 containing recombinant genes for ethanol production on plasmids that are also required for anaerobic growth was cultivated continuously on 50 g/l xylose or glucose in the absence of antibiotics and without the use of special measures to limit the entry of oxygen into the fermenter. Under chemostat conditions, stable ethanol yields of ca. 80-85% of the theoretical were obtained on both sugars over 26 days at dilution rates of 0.045/h (xylose) and 0.075/h (glucose), with average plasmid retention rates of 96% (xylose) and 97% (glucose). In a continuous fluidized bed fermenter, with the cells immobilized on porous glass beads, the extent of plasmid retention by the free cells fell rapidly, while that of the immobilized cells remained constant. This was shown to be due to diffusion of oxygen through the tubing used to recirculate the medium and free cells. A change to oxygen-impermeable tubing led to a stable high rate of plasmid retention (more than 96% of both the free and immobilized cells) with ethanol yields of ca. 80% on a 50 g/l xylose feed. The maximum permissible level of oxygen availability consistent with high plasmid retention by the strain appears to be of the order of 0.1 mmol per hour per gram dry biomass, based on measurements of the rate of oxygen penetration into the fermenters. Revertant colonies lacking the ethanologenic plasmid were easily detectable by their morphology which correlated well with their lack of ampicillin resistance upon transfer plating.
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Affiliation(s)
- Gregory J O Martin
- Department of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, VIC, Australia 3010
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14
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Lin Y, Tanaka S. Ethanol fermentation from biomass resources: current state and prospects. Appl Microbiol Biotechnol 2006; 69:627-42. [PMID: 16331454 DOI: 10.1007/s00253-005-0229-x] [Citation(s) in RCA: 792] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 10/21/2005] [Accepted: 10/22/2005] [Indexed: 10/25/2022]
Abstract
In recent years, growing attention has been devoted to the conversion of biomass into fuel ethanol, considered the cleanest liquid fuel alternative to fossil fuels. Significant advances have been made towards the technology of ethanol fermentation. This review provides practical examples and gives a broad overview of the current status of ethanol fermentation including biomass resources, microorganisms, and technology. Also, the promising prospects of ethanol fermentation are especially introduced. The prospects included are fermentation technology converting xylose to ethanol, cellulase enzyme utilized in the hydrolysis of lignocellulosic materials, immobilization of the microorganism in large systems, simultaneous saccharification and fermentation, and sugar conversion into ethanol.
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Affiliation(s)
- Yan Lin
- Asian Center for Environmental Research, Meisei University, Tokyo, Japan
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15
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Panagiotou G, Christakopoulos P, Olsson L. Simultaneous saccharification and fermentation of cellulose by Fusarium oxysporum F3—growth characteristics and metabolite profiling. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2004.12.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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Lim WJ, Hong SY, An CL, Cho KM, Choi BR, Kim YK, An JM, Kang JM, Lee SM, Cho SJ, Kim H, Yun HD. Construction of minimum size cellulase (Cel5Z) from Pectobacterium chrysanthemi PY35 by removal of the C-terminal region. Appl Microbiol Biotechnol 2005; 68:46-52. [PMID: 15666145 DOI: 10.1007/s00253-004-1880-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Revised: 12/06/2004] [Accepted: 12/13/2004] [Indexed: 10/25/2022]
Abstract
Pectobacterium chrysanthemi PY35 secretes the endoglucanase Cel5Z, an enzyme of the glycoside hydrolase family 5. Cel5Z is a 426 amino acid, signal peptide (SP)-containing protein composed of two domains: a large N-terminal catalytic domain (CD; 291 amino acids) and a small C-terminal cellulose binding domain (CBD; 62 amino acids). These two domains are separated by a 30 amino acid linker region (LR). A truncated cel5Z gene was constructed with the addition of a nonsense mutation that removes the C-terminal region of the protein. A truncated Cel5Z protein, consisting of 280 amino acid residues, functioned as a mature enzyme despite the absence of the SP, 11 amino acid CD, LR, and CBD region. In fact, this truncated Cel5Z protein showed an enzymatic activity 80% higher than that of full-length Cel5Z. However, cellulase activity was undetectable in mature Cel5Z proteins truncated to less than 280 amino acids.
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Affiliation(s)
- Woo Jin Lim
- Division of Applied Life Science, Gyeongsang National University, Chinju, 660-701, Korea
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Ding SJ, Ge W, Buswell JA. Secretion, purification and characterisation of a recombinant Volvariella volvacea endoglucanase expressed in the yeast Pichia pastoris. Enzyme Microb Technol 2002. [DOI: 10.1016/s0141-0229(02)00168-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Golias H, Dumsday GJ, Stanley GA, Pamment NB. Evaluation of a recombinant Klebsiella oxytoca strain for ethanol production from cellulose by simultaneous saccharification and fermentation: comparison with native cellobiose-utilising yeast strains and performance in co-culture with thermotolerant yeast and Zymomonas mobilis. J Biotechnol 2002; 96:155-68. [PMID: 12039532 DOI: 10.1016/s0168-1656(02)00026-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
In the simultaneous saccharification and fermentation to ethanol of 100 g l(-1) microcrystalline cellulose, the cellobiose-fermenting recombinant Klebsiella oxytoca P2 outperformed a range of cellobiose-fermenting yeasts used in earlier work, despite producing less ethanol than reported earlier for this organism under similar conditions. The time taken by K. oxytoca P2 to produce up to about 33 g l(-1) ethanol was much less than for any other organism investigated, including ethanol-tolerant strains of Saccharomyces pastorianus, Kluyveromyces marxianus and Zymomonas mobilis. Ultimately, it produced slightly less ethanol (maximum 36 g l(-1)) than these organisms, reflecting its lower ethanol tolerance. Significant advantages were obtained by co-culturing K. oxytoca P2 with S. pastorianus, K. marxianus or Z. mobilis, either isothermally, or in conjunction with temperature-profiling to raise the cellulase activity. Co-cultures produced significantly more ethanol, more rapidly, than either of the constituent strains in pure culture at the same inoculum density. K. oxytoca P2 dominated the early stages of the co-cultures, with ethanol production in the later stages due principally to the more ethanol tolerant strain. The usefulness of K. oxytoca P2 in cellulose simultaneous saccharification and fermentation should be improved by mutation of the strain to increase its ethanol tolerance.
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Affiliation(s)
- Helen Golias
- Department of Chemical Engineering, University of Melbourne, Parkville, Victoria, Australia
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Sun Y, Cheng J. Hydrolysis of lignocellulosic materials for ethanol production: a review. BIORESOURCE TECHNOLOGY 2002; 83:1-11. [PMID: 12058826 DOI: 10.1016/s0960-8524(01)00212-7] [Citation(s) in RCA: 2066] [Impact Index Per Article: 93.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Lignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The cost of ethanol production from lignocellulosic materials is relatively high based on current technologies, and the main challenges are the low yield and high cost of the hydrolysis process. Considerable research efforts have been made to improve the hydrolysis of lignocellulosic materials. Pretreatment of lignocellulosic materials to remove lignin and hemicellulose can significantly enhance the hydrolysis of cellulose. Optimization of the cellulase enzymes and the enzyme loading can also improve the hydrolysis. Simultaneous saccharification and fermentation effectively removes glucose, which is an inhibitor to cellulase activity, thus increasing the yield and rate of cellulose hydrolysis.
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Affiliation(s)
- Ye Sun
- Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh 27695-7625, USA
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20
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Park SR, Cho SJ, Kim MK, Ryu SK, Lim WJ, An CL, Hong SY, Kim JH, Kim H, Yun HD. Activity enhancement of Cel5Z from Pectobacterium chrysanthemi PY35 by removing C-terminal region. Biochem Biophys Res Commun 2002; 291:425-30. [PMID: 11846423 DOI: 10.1006/bbrc.2002.6437] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The phytopathogenic bacterium Pectobacteium chrysanthemi PY35 secretes Cel5Z endoglucanase belonging to the glycoside hydrolase family 5 of EC 3.2.1.4. The mutation of cel5Z::Omega gene was constructed by cloning the 2.0-kb SmaI fragment containing the streptomycin/spectinomycin-resistance gene of pHP45(Omega) into the BalI site of pPY100. The insertion of Omega fragment generated a new stop codon, removing the Ser/Thr-rich linker region and the cellulose binding domain (CBD) in the C-terminal region of cel5Z gene. By subsequent subcloning from this 4.9-kb fragment (pPY1001), a 1.0-kb (pPY1002) fragment was obtained and designated as cel5Z::Omega. The cel5Z::Omega gene had an open reading frame (ORF) of 1011 bp, encoding 336 amino acids, starting with an ATG codon and ending with a new TGA stop codon. The molecular mass of the Cel5Z::Omega protein in E. coli transformant appeared to be 32 kDa by SDS-PAGE analysis in the presence of carboxymethyl-cellulose (CMC). The Cel5Z::Omega protein hydrolyzed CMC with 1.7-fold higher activity than the intact Cel5Z cellulase.
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Affiliation(s)
- Sang Ryeol Park
- Research Institute of Life Science, Gyeongsang National University, Chinju 660-701, Korea
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Zhou S, Yomano LP, Saleh AZ, Davis FC, Aldrich HC, Ingram LO. Enhancement of expression and apparent secretion of Erwinia chrysanthemi endoglucanase (encoded by celZ) in Escherichia coli B. Appl Environ Microbiol 1999; 65:2439-45. [PMID: 10347024 PMCID: PMC91359 DOI: 10.1128/aem.65.6.2439-2445.1999] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli B has been engineered as a biocatalyst for the conversion of lignocellulose into ethanol. Previous research has demonstrated that derivatives of E. coli B can produce high levels of Erwinia chrysanthemi endoglucanase (encoded by celZ) as a periplasmic product and that this enzyme can function with commercial fungal cellulase to increase ethanol production. In this study, we have demonstrated two methods that improve celZ expression in E. coli B. Initially, with a low-copy-number vector, two E. coli glycolytic gene promoters (gap and eno) were tested and found to be less effective than the original celZ promoter. By screening 18,000 random fragments of Zymomonas mobilis DNA, a surrogate promoter was identified which increased celZ expression up to sixfold. With this promoter, large polar inclusion bodies were clearly evident in the periplasmic space. Sequencing revealed that the most active surrogate promoter is derived from five Sau3A1 fragments, one of which was previously sequenced in Z. mobilis. Visual inspection indicated that this DNA fragment contains at least five putative promoter regions, two of which were confirmed by primer extension analysis. Addition of the out genes from E. chrysanthemi EC16 caused a further increase in the production of active enzyme and facilitated secretion or release of over half of the activity into the extracellular environment. With the most active construct, of a total of 13,000 IU of active enzyme per liter of culture, 7,800 IU was in the supernatant. The total active endoglucanase was estimated to represent 4 to 6% of cellular protein.
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Affiliation(s)
- S Zhou
- Institute of Food and Agricultural Sciences, Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611, USA
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Ingram LO, Gomez PF, Lai X, Moniruzzaman M, Wood BE, Yomano LP, York SW. Metabolic engineering of bacteria for ethanol production. Biotechnol Bioeng 1998. [DOI: 10.1002/(sici)1097-0290(19980420)58:2/3%3c204::aid-bit13%3e3.0.co;2-c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Ingram LO, Gomez PF, Lai X, Moniruzzaman M, Wood BE, Yomano LP, York SW. Metabolic engineering of bacteria for ethanol production. Biotechnol Bioeng 1998; 58:204-14. [PMID: 10191391 DOI: 10.1002/(sici)1097-0290(19980420)58:2/3<204::aid-bit13>3.0.co;2-c] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Technologies are available which will allow the conversion of lignocellulose into fuel ethanol using genetically engineered bacteria. Assembling these into a cost-effective process remains a challenge. Our work has focused primarily on the genetic engineering of enteric bacteria using a portable ethanol production pathway. Genes encoding Zymomonas mobilis pyruvate decarboxylase and alcohol dehydrogenase have been integrated into the chromosome of Escherichia coli B to produce strain KO11 for the fermentation of hemicellulose-derived syrups. This organism can efficiently ferment all hexose and pentose sugars present in the polymers of hemicellulose. Klebsiella oxytoca M5A1 has been genetically engineered in a similar manner to produce strain P2 for ethanol production from cellulose. This organism has the native ability to ferment cellobiose and cellotriose, eliminating the need for one class of cellulase enzymes. The optimal pH for cellulose fermentation with this organism (pH 5.0-5.5) is near that of fungal cellulases. The general approach for the genetic engineering of new biocatalysts has been most successful with enteric bacteria thus far. However, this approach may also prove useful with Gram-positive bacteria which have other important traits for lignocellulose conversion. Many opportunities remain for further improvements in the biomass to ethanol processes. These include the development of enzyme-based systems which eliminate the need for dilute acid hydrolysis or other pretreatments, improvements in existing pretreatments for enzymatic hydrolysis, process improvements to increase the effective use of cellulase and hemicellulase enzymes, improvements in rates of ethanol production, decreased nutrient costs, increases in ethanol concentrations achieved in biomass beers, increased resistance of the biocatalysts to lignocellulosic-derived toxins, etc. To be useful, each of these improvements must result in a decrease in the cost for ethanol production. Copyright 1998 John Wiley & Sons, Inc.
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Affiliation(s)
- LO Ingram
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611, USA
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Moniruzzaman M, Lai X, York SW, Ingram LO. Isolation and molecular characterization of high-performance cellobiose-fermenting spontaneous mutants of ethanologenic Escherichia coli KO11 containing the Klebsiella oxytoca casAB operon. Appl Environ Microbiol 1997; 63:4633-7. [PMID: 9406380 PMCID: PMC168784 DOI: 10.1128/aem.63.12.4633-4637.1997] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Escherichia coli KO11 was previously constructed to produce ethanol from acid hydrolysates of hemicellulose (pentoses and hexoses) by the chromosomal integration of Zymomonas mobilis genes encoding pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adhB). Klebsiella oxytoca P2 was constructed in an analogous fashion for the simultaneous saccharification and fermentation of cellulose and contains PTS enzymes for cellobiose. In this study, KO11 was further engineered for the fermentation of cellulose by adding the K. oxytoca casAB genes encoding Enzyme IIcellobiose and phospho-beta-glucosidase. Although the two K. oxytoca genes were well expressed in cloning hosts such as DH5 alpha, both were expressed poorly in E. coli KO11, a derivative of E. coli B. Spontaneous mutants which exhibited more than 15-fold-higher specific activities for cellobiose metabolism were isolated. The mutations of these mutants resided in the plasmid rather than the host. Three mutants were characterized by sequence analysis. All contained similar internal deletions which eliminated the casAB promoter and operator regions and placed the lacZ Shine-Dalgarno region immediately upstream from the casA Shine-Dalgarno region. KO11 harboring mutant plasmids (pLOI1908, pLOI1909, or pLOI1910) rapidly fermented cellobiose to ethanol, and the yield was more than 90% of the theoretical yield. Two of these strains were used with commercial cellulase to ferment mixed-waste office paper to ethanol.
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Affiliation(s)
- M Moniruzzaman
- Department of Microbiology and Cell Science, University of Florida, Gainesville 32611, USA
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