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Arnthong J, Ponjarat J, Bussadee P, Deenarn P, Prommana P, Phienluphon A, Charoensri S, Champreda V, Zhao XQ, Suwannarangsee S. Enhanced surface display efficiency of β-glucosidase in Saccharomyces cerevisiae by disruption of cell wall protein-encoding genes YGP1 and CWP2. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2021.108305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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2
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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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Shi A, Broach JR. Microbial adaptive evolution. J Ind Microbiol Biotechnol 2021; 49:6407523. [PMID: 34673973 PMCID: PMC9118994 DOI: 10.1093/jimb/kuab076] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 09/27/2021] [Indexed: 01/08/2023]
Abstract
Bacterial species can adapt to significant changes in their environment by mutation followed by selection, a phenomenon known as “adaptive evolution.” With the development of bioinformatics and genetic engineering, research on adaptive evolution has progressed rapidly, as have applications of the process. In this review, we summarize various mechanisms of bacterial adaptive evolution, the technologies used for studying it, and successful applications of the method in research and industry. We particularly highlight the contributions of Dr. L. O. Ingram. Microbial adaptive evolution has significant impact on our society not only from its industrial applications, but also in the evolution, emergence, and control of various pathogens.
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Affiliation(s)
- Aiqin Shi
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - James R Broach
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Munjal N, Jawed K, Wajid S, Yazdani SS. A constitutive expression system for cellulase secretion in Escherichia coli and its use in bioethanol production. PLoS One 2015; 10:e0119917. [PMID: 25768292 PMCID: PMC4358894 DOI: 10.1371/journal.pone.0119917] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/18/2015] [Indexed: 02/05/2023] Open
Abstract
The production of biofuels from lignocellulosic biomass appears to be attractive and viable due to the abundance and availability of this biomass. The hydrolysis of this biomass, however, is challenging because of the complex lignocellulosic structure. The ability to produce hydrolytic cellulase enzymes in a cost-effective manner will certainly accelerate the process of making lignocellulosic ethanol production a commercial reality. These cellulases may need to be produced aerobically to generate large amounts of protein in a short time or anaerobically to produce biofuels from cellulose via consolidated bioprocessing. Therefore, it is important to identify a promoter that can constitutively drive the expression of cellulases under both aerobic and anaerobic conditions without the need for an inducer. Using lacZ as reporter gene, we analyzed the strength of the promoters of four genes, namely lacZ, gapA, ldhA and pflB, and found that the gapA promoter yielded the maximum expression of the β-galactosidase enzyme under both aerobic and anaerobic conditions. We further cloned the genes for two cellulolytic enzymes, β-1,4-endoglucanase and β-1,4-glucosidase, under the control of the gapA promoter, and we expressed these genes in Escherichia coli, which secreted the products into the extracellular medium. An ethanologenic E. colistrain transformed with the secretory β-glucosidase gene construct fermented cellobiose in both defined and complex medium. This recombinant strain also fermented wheat straw hydrolysate containing glucose, xylose and cellobiose into ethanol with an 85% efficiency of biotransformation. An ethanologenic strain that constitutively secretes a cellulolytic enzyme is a promising platform for producing lignocellulosic ethanol.
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Affiliation(s)
- Neha Munjal
- Synthetic Biology and Biofuels Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Kamran Jawed
- Synthetic Biology and Biofuels Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
| | - Saima Wajid
- Centre for Biotechnology, Jamia Hamdard, Hamdard Nagar, New Delhi, India
| | - Syed Shams Yazdani
- Synthetic Biology and Biofuels Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
- DBT-ICGEB Centre for Advanced Bioenergy Research, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India
- * E-mail:
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6
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Comparative engineering of Escherichia coli for cellobiose utilization: Hydrolysis versus phosphorolysis. Metab Eng 2014; 24:9-17. [DOI: 10.1016/j.ymben.2014.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/01/2014] [Accepted: 04/14/2014] [Indexed: 11/20/2022]
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7
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Chen X, Zhou L, Tian K, Kumar A, Singh S, Prior BA, Wang Z. Metabolic engineering of Escherichia coli: A sustainable industrial platform for bio-based chemical production. Biotechnol Adv 2013; 31:1200-23. [DOI: 10.1016/j.biotechadv.2013.02.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/04/2013] [Accepted: 02/25/2013] [Indexed: 12/20/2022]
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Ikeda N, Miyamoto M, Adachi N, Nakano M, Tanaka T, Kondo A. Direct cadaverine production from cellobiose using β-glucosidase displaying Escherichia coli. AMB Express 2013; 3:67. [PMID: 24206923 PMCID: PMC3827850 DOI: 10.1186/2191-0855-3-67] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/31/2013] [Indexed: 11/30/2022] Open
Abstract
In this study, we demonstrate the one-step production of cadaverine (1,5-diaminopentane) from cellobiose using an Escherichia coli strain displaying β-glucosidase (BGL) on its cell surface. L-lysine decarboxylase (CadA) derived from E. coli and BGL from Thermobifida fusca YX (Tfu0937) fused to the anchor protein Blc from E. coli were co-expressed using E. coli as a host. The expression of CadA was confirmed by Western blotting and BGL activity on the cell surface was evaluated using pNPG as a substrate. Growth on cellobiose as the sole carbon source was also achieved. The OD600 value of the BGL and CadA co-expressing strain was 8.0 after 48 h cultivation, which is higher than that obtained by growth on glucose (5.4 after 48 h cultivation). The engineered strain produced cadaverine from cellobiose more effectively than from glucose: 6.1 mM after 48 h from 28 g/L of consumed cellobiose, vs. 3.3 mM from 20 g/L of consumed glucose.
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Inefficient translation renders the Enterococcus faecalis fabK enoyl-acyl carrier protein reductase phenotypically cryptic. J Bacteriol 2013; 196:170-9. [PMID: 24163335 DOI: 10.1128/jb.01148-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enoyl-acyl carrier protein (ACP) reductase catalyzes the last step of the bacterial fatty acid elongation cycle. Enterococcus faecalis is unusual in that it encodes two unrelated enoyl-ACP reductases, FabI and FabK. We recently reported that deletion of the gene encoding FabI results in an unsaturated fatty acid (UFA) auxotroph despite the presence of fabK, a gene encoding a second fully functional enoyl-ACP reductase. By process of elimination, our prior report argued that poor expression was the reason that fabK failed to functionally replace FabI. We now report that FabK is indeed poorly expressed and that the expression defect is at the level of translation rather than transcription. We isolated four spontaneous mutants that allowed growth of the E. faecalis ΔfabI strain on fatty acid-free medium. Each mutational lesion (single base substitution or deletion) extended the fabK ribosome binding site. Inactivation of fabK blocked growth, indicating that the mutations acted only on fabK rather than a downstream gene. The mutations activated fabK translation to levels that supported fatty acid synthesis and hence cell growth. Furthermore, site-directed and random mutagenesis experiments showed that point mutations that resulted in increased complementarity to the 3' end of the 16S rRNA increased FabK translation to levels sufficient to support growth, whereas mutations that decreased complementarity blocked fabK translation.
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Imamoglu E, Dalay MC, Sukan FV. Regional Differences in Rice Hulls Supply for Bioethanol Production. Appl Biochem Biotechnol 2013; 171:2065-74. [DOI: 10.1007/s12010-013-0504-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 08/30/2013] [Indexed: 11/27/2022]
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Imamoglu E, Sukan FV. Scale-up and kinetic modeling for bioethanol production. BIORESOURCE TECHNOLOGY 2013; 144:311-320. [PMID: 23886851 DOI: 10.1016/j.biortech.2013.06.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 06/27/2013] [Accepted: 06/29/2013] [Indexed: 06/02/2023]
Abstract
Bioethanol was produced from acidic hydrolysate of rice hulls using recombinant Escherichia coli KO11. Two different issues (scale-up and kinetic modeling) were evaluated simultaneously and concomitantly for bioethanol production. During the step-wise scale-up process from 100 mL shaken flask to 10 L stirred-tank bioreactor, the constant Reynolds number and the constant impeller tip speed were evaluated as scale-up methodologies under laboratory conditions. It was determined that the volumetric bioethanol productivity was 88% higher in 10 L bioreactor in comparison to the value of 0.21 g L(-1) h(-1) in shaken flask. The modified Monod and Luedeking-Piret models provided an accurate approach for the modeling of the experimental data. Ethanol concentration reached the maximum level of 29.03 g/L, which was 5% higher than the value of model prediction in 10 L bioreactor. The findings of this research could contribute to the industrial scale productions especially from lignocellulosic raw materials.
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Affiliation(s)
- Esra Imamoglu
- Department of Bioengineering, Faculty of Engineering, University of Ege, 35100 Bornova, Izmir, Turkey.
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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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13
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Cell surface display of a β-glucosidase employing the type V secretion system on ethanologenic Escherichia coli for the fermentation of cellobiose to ethanol. J Ind Microbiol Biotechnol 2012; 39:1141-52. [PMID: 22638789 DOI: 10.1007/s10295-012-1122-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/16/2012] [Indexed: 01/19/2023]
Abstract
We used the autodisplay system AIDA-I, which belongs to the type V secretion system (TVSS), to display the β-glucosidase BglC from Thermobifida fusca on the outer membrane of the ethanologenic Escherichia coli strain MS04 (MG1655 ∆pflB, ∆adhE, ∆frdA, ∆xylFGH, ∆ldhA, PpflB::pdc (Zm)-adhB (Zm)). MS04 that was transformed with the plasmid pAIDABglCRHis showed cellobiase activity (171 U/g(CDW)) and fermented 40 g/l cellobiose in mineral medium in 60 h with an ethanol yield of 81 % of the theoretical maximum. Whole-cell protease treatment, SDS-PAGE, and Western-blot analysis demonstrated that BglC was attached to the external surface of the outer membrane of MS04. When attached to the cells, BglC showed 93.3 % relative activity in the presence of 40 g/l ethanol and retained 100 % of its activity following 2 days of incubation at 37 °C with the same ethanol concentration. This study shows the potential of the TVSS (AIDA-I) and BglC as tools for the production of lignocellulosic bio-commodities.
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Engineering Escherichia coli cells for cellobiose assimilation through a phosphorolytic mechanism. Appl Environ Microbiol 2011; 78:1611-4. [PMID: 22194295 DOI: 10.1128/aem.06693-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here the first engineering effort for Escherichia coli biocatalysts to assimilate cellobiose through a phosphorolytic mechanism. Cytoplasmic expression of the Saccharophagus cellobiose phosphorylase was shown to enable E. coli to use cellobiose. Subsequent knockout and complementation studies provided solid evidence that the endogenous LacY was responsible for the transport of cellobiose.
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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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Vinuselvi P, Lee SK. Engineering Escherichia coli for efficient cellobiose utilization. Appl Microbiol Biotechnol 2011; 92:125-32. [PMID: 21713510 DOI: 10.1007/s00253-011-3434-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/09/2011] [Accepted: 06/02/2011] [Indexed: 12/11/2022]
Abstract
Escherichia coli normally cannot utilize the β-glucoside sugar cellobiose as a carbon and energy source unless a stringent selection pressure for survival is present. The cellobiose-utilization phenotype can be conferred by mutations in the two cryptic operons, chb and asc. In this study, the cellobiose-utilization phenotype was conferred to E. coli by replacing the cryptic promoters of these endogenous operons with a constitutive promoter. Evolutionary adaptation of the engineered strain CP12CHBASC by repeated subculture in cellobiose-containing minimal medium led to an increase in the rate of cellobiose uptake and cell growth on cellobiose. An efficient cellobiose-metabolizing E. coli strain would be of great importance over glucose-metabolizing E. coli for a simultaneous saccharification and fermentation process, as the cost of the process would be reduced by eliminating one of the three enzymes needed to hydrolyze cellulose into simple sugars.
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Affiliation(s)
- Parisutham Vinuselvi
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Republic of Korea
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Addition of genes for cellobiase and pectinolytic activity in Escherichia coli for fuel ethanol production from pectin-rich lignocellulosic biomass. Appl Environ Microbiol 2011; 77:5184-91. [PMID: 21666025 DOI: 10.1128/aem.05700-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ethanologenic Escherichia coli strain KO11 was sequentially engineered to contain the Klebsiella oxytoca cellobiose phosphotransferase genes (casAB) as well as a pectate lyase (pelE) from Erwinia chrysanthemi, yielding strains LY40A (casAB) and JP07 (casAB pelE), respectively. To obtain an effective secretion of PelE, the Sec-dependent pathway out genes from E. chrysanthemi were provided on a cosmid to strain JP07 to construct strain JP07C. Finally, oligogalacturonide lyase (ogl) from E. chrysanthemi was added to produce strain JP08C. E. coli strains LY40A, JP07, JP07C, and JP08C possessed significant cellobiase activity in cell lysates, while only strains JP07C and JP08C demonstrated extracellular pectate lyase activity. Fermentations conducted by using a mixture of pure sugars representative of the composition of sugar beet pulp (SBP) showed that strains LY40A, JP07, JP07C, and JP08C were able to ferment cellobiose, resulting in increased ethanol production from 15 to 45% in comparison to that of KO11. Fermentations with SBP at very low fungal enzyme loads during saccharification revealed significantly higher levels of ethanol production for LY40A, JP07C, and JP08C than for KO11. JP07C ethanol yields were not considerably higher than those of LY40A; however, oligogalacturonide polymerization studies showed an increased breakdown of biomass to small-chain (degree of polymerization, ≤6) oligogalacturonides. JP08C achieved a further breakdown of polygalacturonate to monomeric sugars, resulting in a 164% increase in ethanol yields compared to those of KO11. The addition of commercial pectin methylesterase (PME) further increased JP08C ethanol production compared to that of LY40A by demethylating the pectin for enzymatic attack by pectin-degrading enzymes.
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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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Metabolic engineering for production of biorenewable fuels and chemicals: contributions of synthetic biology. J Biomed Biotechnol 2010; 2010:761042. [PMID: 20414363 PMCID: PMC2857869 DOI: 10.1155/2010/761042] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 12/18/2009] [Accepted: 01/13/2010] [Indexed: 12/18/2022] Open
Abstract
Production of fuels and chemicals through microbial fermentation of plant material is a desirable alternative to petrochemical-based production. Fermentative production of biorenewable fuels and chemicals requires the engineering of biocatalysts that can quickly and efficiently convert sugars to target products at a cost that is competitive with existing petrochemical-based processes. It is also important that biocatalysts be robust to extreme fermentation conditions, biomass-derived inhibitors, and their target products. Traditional metabolic engineering has made great advances in this area, but synthetic biology has contributed and will continue to contribute to this field, particularly with next-generation biofuels. This work reviews the use of metabolic engineering and synthetic biology in biocatalyst engineering for biorenewable fuels and chemicals production, such as ethanol, butanol, acetate, lactate, succinate, alanine, and xylitol. We also examine the existing challenges in this area and discuss strategies for improving biocatalyst tolerance to chemical inhibitors.
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Optimization of metabolic pathways for bioconversion of lignocellulose to ethanol through genetic engineering. Biotechnol Adv 2009; 27:593-8. [DOI: 10.1016/j.biotechadv.2009.04.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Revised: 01/20/2009] [Indexed: 11/19/2022]
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Peterson JD, Ingram LO. Anaerobic respiration in engineered Escherichia coli with an internal electron acceptor to produce fuel ethanol. Ann N Y Acad Sci 2008; 1125:363-72. [PMID: 18378606 DOI: 10.1196/annals.1419.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Environmental concerns and unease with U.S. dependence on foreign oil have renewed interest in converting biomass into fuel ethanol. The volume of plant matter available makes lignocellulose conversion to ethanol desirable, although no one isolated organism has been shown to break bonds in lignocellulose and efficiently metabolize resulting sugars into one product. This work reviews directed engineering coupled with metabolic evolution resulting in microbial biocatalysts that produce up to 45 g L(-1) ethanol in 48 hours in a simple mineral salts medium and that convert various compounds of lignocellulosic materials to ethanol. Mutations contributing to ethanologenesis are discussed along with adding enzymatic capabilities to existing biocatalysts in order to decrease the commercial enzymes required to reduce plant matter into fermentable sugars.
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22
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Selection and characterization of mannanase-producing bacteria useful for the formation of prebiotic manno-oligosaccharides from copra meal. World J Microbiol Biotechnol 2007. [DOI: 10.1007/s11274-007-9627-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Jarboe LR, Grabar TB, Yomano LP, Shanmugan KT, Ingram LO. Development of ethanologenic bacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:237-61. [PMID: 17665158 DOI: 10.1007/10_2007_068] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The utilization of lignocellulosic biomass as a petroleum alternative faces many challenges. This work reviews recent progress in the engineering of Escherichia coli and Klebsiella oxytoca to produce ethanol from biomass with minimal nutritional supplementation. A combination of directed engineering and metabolic evolution has resulted in microbial biocatalysts that produce up to 45 g L(-1) ethanol in 48 h in a simple mineral salts medium, and convert various lignocellulosic materials to ethanol. Mutations contributing to ethanologenesis are discussed. The ethanologenic biocatalyst design approach was applied to other commodity chemicals, including optically pure D: (-)- and L: (+)-lactic acid, succinate and L: -alanine with similar success. This review also describes recent progress in growth medium development, the reduction of hemicellulose hydrolysate toxicity and reduction of the demand for fungal cellulases.
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Affiliation(s)
- L R Jarboe
- Department of Microbiology and Cell Science, University of Florida, 32611, Gainesville, FL 32611, USA.
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Zhou S, Yomano LP, Shanmugam KT, Ingram LO. Fermentation of 10% (w/v) sugar to D: (-)-lactate by engineered Escherichia coli B. Biotechnol Lett 2006; 27:1891-6. [PMID: 16328986 DOI: 10.1007/s10529-005-3899-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 09/26/2005] [Accepted: 09/27/2005] [Indexed: 10/25/2022]
Abstract
Derivatives of ethanologenic Escherichia coli K011 were constructed for D: (-)-lactate production by deleting genes encoding competing pathways followed by metabolic evolution, a growth-based selection for mutants with improved performance. Resulting strains, SZ132 and SZ186, contain native genes for sucrose utilization. No foreign genes are present in SZ186. Strain SZ132 also contains a chromosomally integrated endoglucanase gene (Erwinia chrysanthemi celY). Strain SZ132 produced over 1 mol lactate per liter of complex medium containing 10% (w/v) sugar (fermentation times of 48 h for glucose, 120 h for sucrose). Both strains produced 667-700 mmol lactate per liter of mineral salts medium. Yields for metabolized sugar ranged from 88% to 95% in both media.
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Affiliation(s)
- S Zhou
- Department of Biological Sciences, Northern Illinois University, Dekalb, IL 60115, USA
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Qian Y, Yomano LP, Preston JF, Aldrich HC, Ingram LO. Cloning, characterization, and functional expression of the Klebsiella oxytoca xylodextrin utilization operon (xynTB) in Escherichia coli. Appl Environ Microbiol 2004; 69:5957-67. [PMID: 14532050 PMCID: PMC201249 DOI: 10.1128/aem.69.10.5957-5967.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli is being developed as a biocatalyst for bulk chemical production from inexpensive carbohydrates derived from lignocellulose. Potential substrates include the soluble xylodextrins (xyloside, xylooligosaccharide) and xylobiose that are produced by treatments designed to expose cellulose for subsequent enzymatic hydrolysis. Adjacent genes encoding xylobiose uptake and hydrolysis were cloned from Klebsiella oxytoca M5A1 and are functionally expressed in ethanologenic E. coli. The xylosidase encoded by xynB contains the COG3507 domain characteristic of glycosyl hydrolase family 43. The xynT gene encodes a membrane protein containing the MelB domain (COG2211) found in Na(+)/melibiose symporters and related proteins. These two genes form a bicistronic operon that appears to be regulated by xylose (XylR) and by catabolite repression in both K. oxytoca and recombinant E. coli. Homologs of this operon were found in Klebsiella pneumoniae, Lactobacillus lactis, E. coli, Clostridium acetobutylicum, and Bacillus subtilis based on sequence comparisons. Based on similarities in protein sequence, the xynTB genes in K. oxytoca appear to have originated from a gram-positive ancestor related to L. lactis. Functional expression of xynB allowed ethanologenic E. coli to metabolize xylodextrins (xylosides) containing up to six xylose residues without the addition of enzyme supplements. 4-O-methylglucuronic acid substitutions at the nonreducing termini of soluble xylodextrins blocked further degradation by the XynB xylosidase. The rate of xylodextrin utilization by recombinant E. coli was increased when a full-length xynT gene was included with xynB, consistent with xynT functioning as a symport. Hydrolysis rates were inversely related to xylodextrin chain length, with xylobiose as the preferred substrate. Xylodextrins were utilized more rapidly by recombinant E. coli than K. oxytoca M5A1 (the source of xynT and xynB). XynB exhibited weak arabinosidase activity, 3% that of xylosidase.
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Affiliation(s)
- Yilei Qian
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611
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Zhou S, Davis FC, Ingram LO. Gene integration and expression and extracellular secretion of Erwinia chrysanthemi endoglucanase CelY (celY) and CelZ (celZ) in ethanologenic Klebsiella oxytoca P2. Appl Environ Microbiol 2001; 67:6-14. [PMID: 11133422 PMCID: PMC92505 DOI: 10.1128/aem.67.1.6-14.2001] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of methods to reduce costs associated with the solubilization of cellulose is essential for the utilization of lignocellulose as a renewable feedstock for fuels and chemicals. One promising approach is the genetic engineering of ethanol-producing microorganisms that also produce cellulase enzymes during fermentation. By starting with an ethanologenic derivative (strain P2) of Klebsiella oxytoca M5A1 with the native ability to metabolize cellobiose, the need for supplemental beta-glucosidase was previously eliminated. In the current study, this approach has been extended by adding genes encoding endoglucanase activities. Genes celY and celZ from Erwinia chrysanthemi have been functionally integrated into the chromosome of P2 using surrogate promoters from Zymomonas mobilis for expression. Both were secreted into the extracellular milieu, producing more than 20,000 endoglucanase units (carboxymethyl cellulase activity) per liter of fermentation broth. During the fermentation of crystalline cellulose with low levels of commercial cellulases of fungal origin, these new strains produced up to 22% more ethanol than unmodified P2. Most of the beneficial contribution was attributed to CelY rather than to CelZ. These results suggest that fungal enzymes with substrate profiles resembling CelY (preference for long-chain polymers and lack of activity on soluble cello-oligosaccharides of two to five glucosyl residues) may be limiting in commercial cellulase preparations.
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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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Jeffries TW, Shi NQ. Genetic engineering for improved xylose fermentation by yeasts. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 1999; 65:117-61. [PMID: 10533434 DOI: 10.1007/3-540-49194-5_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Xylose utilization is essential for the efficient conversion of lignocellulosic materials to fuels and chemicals. A few yeasts are known to ferment xylose directly to ethanol. However, the rates and yields need to be improved for commercialization. Xylose utilization is repressed by glucose which is usually present in lignocellulosic hydrolysates, so glucose regulation should be altered in order to maximize xylose conversion. Xylose utilization also requires low amounts of oxygen for optimal production. Respiration can reduce ethanol yields, so the role of oxygen must be better understood and respiration must be reduced in order to improve ethanol production. This paper reviews the central pathways for glucose and xylose metabolism, the principal respiratory pathways, the factors determining partitioning of pyruvate between respiration and fermentation, the known genetic mechanisms for glucose and oxygen regulation, and progress to date in improving xylose fermentations by yeasts.
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Affiliation(s)
- T W Jeffries
- USDA, Forest Service, Institute for Microbial and Biochemical Technology, Madison, WI 53705, USA
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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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