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Yarbrough JM, Mittal A, Mansfield E, Taylor LE, Hobdey SE, Sammond DW, Bomble YJ, Crowley MF, Decker SR, Himmel ME, Vinzant TB. New perspective on glycoside hydrolase binding to lignin from pretreated corn stover. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:214. [PMID: 26691693 PMCID: PMC4683727 DOI: 10.1186/s13068-015-0397-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/30/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND Non-specific binding of cellulases to lignin has been implicated as a major factor in the loss of cellulase activity during biomass conversion to sugars. It is believed that this binding may strongly impact process economics through loss of enzyme activities during hydrolysis and enzyme recycling scenarios. The current model suggests glycoside hydrolase activities are lost though non-specific/non-productive binding of carbohydrate-binding domains to lignin, limiting catalytic site access to the carbohydrate components of the cell wall. RESULTS In this study, we have compared component enzyme affinities of a commercial Trichoderma reesei cellulase formulation, Cellic CTec2, towards extracted corn stover lignin using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and p-nitrophenyl substrate activities to monitor component binding, activity loss, and total protein binding. Protein binding was strongly affected by pH and ionic strength. β-d-glucosidases and xylanases, which do not have carbohydrate-binding modules (CBMs) and are basic proteins, demonstrated the strongest binding at low ionic strength, suggesting that CBMs are not the dominant factor in enzyme adsorption to lignin. Despite strong adsorption to insoluble lignin, β-d-glucosidase and xylanase activities remained high, with process yields decreasing only 4-15 % depending on lignin concentration. CONCLUSION We propose that specific enzyme adsorption to lignin from a mixture of biomass-hydrolyzing enzymes is a competitive affinity where β-d-glucosidases and xylanases can displace CBM interactions with lignin. Process parameters, such as temperature, pH, and salt concentration influence the individual enzymes' affinity for lignin, and both hydrophobic and electrostatic interactions are responsible for this binding phenomenon. Moreover, our results suggest that concern regarding loss of critical cell wall degrading enzymes to lignin adsorption may be unwarranted when complex enzyme mixtures are used to digest biomass.
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Affiliation(s)
- John M. Yarbrough
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Ashutosh Mittal
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | | | - Larry E. Taylor
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | | | - Deanne W. Sammond
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Yannick J. Bomble
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Michael F. Crowley
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Stephen R. Decker
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Michael E. Himmel
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
| | - Todd B. Vinzant
- />Biosciences Center, National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401 USA
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Wei H, Fu Y, Magnusson L, Baker JO, Maness PC, Xu Q, Yang S, Bowersox A, Bogorad I, Wang W, Tucker MP, Himmel ME, Ding SY. Comparison of transcriptional profiles of Clostridium thermocellum grown on cellobiose and pretreated yellow poplar using RNA-Seq. Front Microbiol 2014; 5:142. [PMID: 24782837 PMCID: PMC3990059 DOI: 10.3389/fmicb.2014.00142] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/19/2014] [Indexed: 01/01/2023] Open
Abstract
The anaerobic, thermophilic bacterium, Clostridium thermocellum, secretes multi-protein enzyme complexes, termed cellulosomes, which synergistically interact with the microbial cell surface and efficiently disassemble plant cell wall biomass. C. thermocellum has also been considered a potential consolidated bioprocessing (CBP) organism due to its ability to produce the biofuel products, hydrogen, and ethanol. We found that C. thermocellum fermentation of pretreated yellow poplar (PYP) produced 30 and 39% of ethanol and hydrogen product concentrations, respectively, compared to fermentation of cellobiose. RNA-seq was used to analyze the transcriptional profiles of these cells. The PYP-grown cells taken for analysis at the late stationary phase showed 1211 genes up-regulated and 314 down-regulated by more than two-fold compared to the cellobiose-grown cells. These affected genes cover a broad spectrum of specific functional categories. The transcriptional analysis was further validated by sub-proteomics data taken from the literature; as well as by quantitative reverse transcription-PCR (qRT-PCR) analyses of selected genes. Specifically, 47 cellulosomal protein-encoding genes, genes for 4 pairs of SigI-RsgI for polysaccharide sensing, 7 cellodextrin ABC transporter genes, and a set of NAD(P)H hydogenase and alcohol dehydrogenase genes were up-regulated for cells growing on PYP compared to cellobiose. These genes could be potential candidates for future studies aimed at gaining insight into the regulatory mechanism of this organism as well as for improvement of C. thermocellum in its role as a CBP organism.
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Affiliation(s)
- Hui Wei
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Yan Fu
- Center for Plant Genomics, Iowa State University Ames, IA, USA
| | - Lauren Magnusson
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - John O Baker
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Pin-Ching Maness
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Qi Xu
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Shihui Yang
- National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Andrew Bowersox
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA ; National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Igor Bogorad
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Wei Wang
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Melvin P Tucker
- National Bioenergy Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Michael E Himmel
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
| | - Shi-You Ding
- Biosciences Center, National Renewable Energy Laboratory Golden, CO, USA
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El-Ahmady N, Deraz S, Khalil A. Bioethanol Production from Lignocellulosic Feedstocks Based on Enzymatic Hydrolysis:
Current Status and Recent Developments. ACTA ACUST UNITED AC 2013. [DOI: 10.3923/biotech.2014.1.21] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Wallace BA, Judd TM. A test of seasonal responses to sugars in four populations of the termite Reticulitermes flavipes. JOURNAL OF ECONOMIC ENTOMOLOGY 2010; 103:2126-2131. [PMID: 21309235 DOI: 10.1603/ec09326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Several studies have shown that Reticulitermes termites prefer food with certain types of sugars. However, the specific sugars that were preferred by the termites in each study differed. The difference between the results of these studies might be explained by differences between populations or changes in feeding responses during the active season. To address these variables, we examined the feeding response to a food source food containing glucose, sucrose, or xylose versus a food source without sugar in several populations of termites and observed whether these responses changed during the year. Termites were collected from colonies from four field sites in Missouri during the spring (May and June), summer (July and August), and fall (September and October) and tested for their response to all three sugars under laboratory conditions. Results show there are distinct differences in response to sugars between populations but only a slight seasonal effect.
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Affiliation(s)
- Bruce A Wallace
- Department of Biology, Southeast Missouri State University, Cape Girardeau, MO 63701, USA.
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Sluiter JB, Ruiz RO, Scarlata CJ, Sluiter AD, Templeton DW. Compositional analysis of lignocellulosic feedstocks. 1. Review and description of methods. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:9043-53. [PMID: 20669951 PMCID: PMC2923870 DOI: 10.1021/jf1008023] [Citation(s) in RCA: 354] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
As interest in lignocellulosic biomass feedstocks for conversion into transportation fuels grows, the summative compositional analysis of biomass, or plant-derived material, becomes ever more important. The sulfuric acid hydrolysis of biomass has been used to measure lignin and structural carbohydrate content for more than 100 years. Researchers have applied these methods to measure the lignin and structural carbohydrate contents of woody materials, estimate the nutritional value of animal feed, analyze the dietary fiber content of human food, compare potential biofuels feedstocks, and measure the efficiency of biomass-to-biofuels processes. The purpose of this paper is to review the history and lineage of biomass compositional analysis methods based on a sulfuric acid hydrolysis. These methods have become the de facto procedure for biomass compositional analysis. The paper traces changes to the biomass compositional analysis methods through time to the biomass methods currently used at the National Renewable Energy Laboratory (NREL). The current suite of laboratory analytical procedures (LAPs) offered by NREL is described, including an overview of the procedures and methodologies and some common pitfalls. Suggestions are made for continuing improvement to the suite of analyses.
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Affiliation(s)
| | | | | | | | - David W. Templeton
- Corresponding author [e-mail ; phone (303) 384-7764; fax (303) 384-6877]
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Chen HZ, Xu J, Li ZH. Temperature cycling to improve the ethanol production with solid state simultaneous saccharification and fermentation. APPL BIOCHEM MICRO+ 2007. [DOI: 10.1134/s0003683807010103] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Auto-hydrolysis of lignocellulosics under extremely low sulphuric acid and high temperature conditions in batch reactor. BIOTECHNOL BIOPROC E 2003. [DOI: 10.1007/bf02949219] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Torget RW, Kim JS, Lee YY. Fundamental Aspects of Dilute Acid Hydrolysis/Fractionation Kinetics of Hardwood Carbohydrates. 1. Cellulose Hydrolysis. Ind Eng Chem Res 2000. [DOI: 10.1021/ie990915q] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Robert W. Torget
- Biotechnology Center for Fuels and Chemicals, National Renewable Energy Laboratory, Golden, Colorado 80401
| | - Jun Seok Kim
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849
| | - Y. Y. Lee
- Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849
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Stenberg K, Bollók M, Réczey K, Galbe M, Zacchi G. Effect of substrate and cellulase concentration on simultaneous saccharification and fermentation of steam-pretreated softwood for ethanol production. Biotechnol Bioeng 2000; 68:204-10. [PMID: 10712736 DOI: 10.1002/(sici)1097-0290(20000420)68:2<204::aid-bit9>3.0.co;2-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Economic optimization of the production of ethanol by simultaneous saccharification and fermentation (SSF) requires knowledge about the influence of substrate and enzyme concentration on yield and productivity. Although SSF has been investigated extensively, the optimal conditions for SSF of softwoods have yet not been determined. In this study, SO2-impregnated and steam-pretreated spruce was used as substrate for the production of ethanol by SSF. Commercial enzymes were used in combination with the yeast Saccharomyces cerevisiae. The effects of the concentration of substrate (2% to 10% w/w) and of cellulases (5 to 32 FPU/g cellulose) were investigated. SSF was found to be sensitive to contamination because lactic acid was produced. The ethanol yield increased with increasing cellulase loading. The highest ethanol yield, 68% of the theoretical based on the glucose and mannose present in the original wood, was obtained at 5% substrate concentration. This yield corresponds to 82% of the theoretical based on the cellulose and soluble glucose and mannose present at the start of SSF. A higher substrate concentration caused inefficient fermentation, whereas a lower substrate concentration, 2%, resulted in increased formation of lactic acid, which lowered the yield. Compared with separate hydrolysis and fermentation, SSF gave a higher yield and doubled the productivity.
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Affiliation(s)
- K Stenberg
- Department of Chemical Engineering I, Lund University, P.O. Box 124, SE-221 00, Lund, Sweden
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Stenberg K, Galbe M, Zacchi G. The influence of lactic acid formation on the simultaneous saccharification and fermentation (SSF) of softwood to ethanol. Enzyme Microb Technol 2000. [DOI: 10.1016/s0141-0229(99)00127-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Pretreatment of softwood by acid-catalyzed steam explosion followed by alkali extraction. Appl Biochem Biotechnol 1998. [DOI: 10.1007/bf02920120] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Chung YC, Bakalinsky A, Penner MH. Analysis of biomass cellulose in simultaneous saccharification and fermentation processes. Appl Biochem Biotechnol 1997; 66:249-62. [PMID: 9276923 DOI: 10.1007/bf02785591] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A direct method for determining the cellulose content of biomass residues resulting from simultaneous saccharifiaction and fermentation (SSF) experiment has been developed and evaluated. The method improves on classical cellulose assays by incorporating the enzymatic removal of yeast glucans from the biomass residue prior to acid hydrolysis and subsequent quantification of cellulose-derived glucose. An appropriate cellulase-free, commercially available, yeast-lysing enzyme preparation from Cytophaga was identified. A freeze-drying step was identified as necessary to render the SSF yeast cells susceptible to enzymatic lysis. The method was applied to the analysis of cellulose and yeast-associated glucans in SSF residues from three pretreated feedstocks; hybrid poplar, switchgrass, and cornstover. Cellulose assays employing the lysing-enzyme preparation demonstrated relative errors up to 7.2% when yeast-associated glucans were not removed prior to analysis of SSF residues. Enzymatic lysis of SSF yeast cells may be viewed as a general preparatory procedure to be used prior to subsequent chemical and physical analysis of SSF residues.
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Affiliation(s)
- Y C Chung
- Department of Food Science and Technology Oregon State University, Corvallis 97331-6602, USA
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Baker JO, Vinzant TB, Ehrman CI, Adney WS, Himmel ME. Use of a new membrane-reactor saccharification assay to evaluate the performance of celluloses under simulated ssf conditions. Appl Biochem Biotechnol 1997; 63-65:585-95. [DOI: 10.1007/bf02920456] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Rivard CJ, Engel RE, Hayward TK, Nagle NJ, Hatzis C, Philippidis GP. Measurement of the inhibitory potential and detoxification of biomass pretreatment hydrolysate for ethanol production. Appl Biochem Biotechnol 1996. [DOI: 10.1007/bf02941698] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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