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Bioconversion of a Lignocellulosic Hydrolysate to Single Cell Oil for Biofuel Production in a Cost-Efficient Fermentation Process. FERMENTATION-BASEL 2023. [DOI: 10.3390/fermentation9020189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Cutaneotrichosporon oleaginosus is a highly efficient single cell oil producer, which in addition to hexoses and pentoses can metabolize organic acids. In this study, fed-batch cultivation with consumption-based acetic acid feeding was further developed to integrate the transformation of an industrial paper mill lignocellulosic hydrolysate (LCH) into yeast oil. Employing pentose-rich LCH as a carbon source instead of glucose significantly improved both biomass formation and lipid titer, reaching 55.73 ± 5.20 g/L and 42.1 ± 1.7 g/L (75.5% lipid per biomass), respectively. This hybrid approach of using acetic acid and LCH in one process was further optimized to increase the share of bioavailable carbon from LCH using a combination of consumption-based and continuous feeding. Finally, the techno-economic analysis revealed a 26% cost reduction when using LCH instead of commercial glucose. In summary, we developed a process leading to a holistic approach to valorizing a pentose-rich industrial waste by converting it into oleochemicals.
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Second Generation Bioethanol Production: On the Use of Pulp and Paper Industry Wastes as Feedstock. FERMENTATION-BASEL 2018. [DOI: 10.3390/fermentation5010004] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Due to the health and environment impacts of fossil fuels utilization, biofuels have been investigated as a potential alternative renewable source of energy. Bioethanol is currently the most produced biofuel, mainly of first generation, resulting in food-fuel competition. Second generation bioethanol is produced from lignocellulosic biomass, but a costly and difficult pretreatment is required. The pulp and paper industry has the biggest income of biomass for non-food-chain production, and, simultaneously generates a high amount of residues. According to the circular economy model, these residues, rich in monosaccharides, or even in polysaccharides besides lignin, can be utilized as a proper feedstock for second generation bioethanol production. Biorefineries can be integrated in the existing pulp and paper industrial plants by exploiting the high level of technology and also the infrastructures and logistics that are required to fractionate and handle woody biomass. This would contribute to the diversification of products and the increase of profitability of pulp and paper industry with additional environmental benefits. This work reviews the literature supporting the feasibility of producing ethanol from Kraft pulp, spent sulfite liquor, and pulp and paper sludge, presenting and discussing the practical attempt of biorefineries implementation in pulp and paper mills for bioethanol production.
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Gao X, Gao Q, Bao J. Tolerance response and metabolism of acetic acid by biodetoxification fungus Amorphotheca resinae ZN1. J Biotechnol 2018; 275:31-39. [DOI: 10.1016/j.jbiotec.2018.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/16/2018] [Accepted: 03/23/2018] [Indexed: 01/09/2023]
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Ur-Rehman S, Mushtaq Z, Zahoor T, Jamil A, Murtaza MA. Xylitol: a review on bioproduction, application, health benefits, and related safety issues. Crit Rev Food Sci Nutr 2016; 55:1514-28. [PMID: 24915309 DOI: 10.1080/10408398.2012.702288] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Xylitol is a pentahydroxy sugar-alcohol which exists in a very low quantity in fruits and vegetables (plums, strawberries, cauliflower, and pumpkin). On commercial scale, xylitol can be produced by chemical and biotechnological processes. Chemical production is costly and extensive in purification steps. However, biotechnological method utilizes agricultural and forestry wastes which offer the possibilities of economic production of xylitol by reducing required energy. The precursor xylose is produced from agricultural biomass by chemical and enzymatic hydrolysis and can be converted to xylitol primarily by yeast strain. Hydrolysis under acidic condition is the more commonly used practice influenced by various process parameters. Various fermentation process inhibitors are produced during chemical hydrolysis that reduce xylitol production, a detoxification step is, therefore, necessary. Biotechnological xylitol production is an integral process of microbial species belonging to Candida genus which is influenced by various process parameters such as pH, temperature, time, nitrogen source, and yeast extract level. Xylitol has application and potential for food and pharmaceutical industries. It is a functional sweetener as it has prebiotic effects which can reduce blood glucose, triglyceride, and cholesterol level. This review describes recent research developments related to bioproduction of xylitol from agricultural wastes, application, health, and safety issues.
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Affiliation(s)
- Salim Ur-Rehman
- a National Institute of Food Science & Technology, University of Agriculture , Faisalabad , 38040 , Pakistan
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Lee SC. Removal of acetic acid from simulated hemicellulosic hydrolysates by emulsion liquid membrane with organophosphorus extractants. BIORESOURCE TECHNOLOGY 2015; 192:340-345. [PMID: 26056774 DOI: 10.1016/j.biortech.2015.05.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/24/2015] [Accepted: 05/25/2015] [Indexed: 06/04/2023]
Abstract
Selective removal of acetic acid from simulated hemicellulosic hydrolysates containing xylose and sulfuric acid was attempted in a batch emulsion liquid membrane (ELM) system with organophosphorus extractants. Various experimental variables were used to develop a more energy-efficient ELM process. Total operation time of an ELM run with a very small quantity of trioctylphosphine oxide as the extractant was reduced to about a third of those required to attain almost the same extraction efficiency as obtained in previous ELM works without any extractant. Under specific conditions, acetic acid was selectively separated with a high degree of extraction and insignificant loss of xylose, and its purity and enrichment ratio in the stripping phase were higher than 92% and 6, respectively. Also, reused organic membrane solutions exhibited the extraction efficiency as high as fresh organic solutions did. These results showed that the current ELM process would be quite practical.
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Affiliation(s)
- Sang Cheol Lee
- Department of Chemical Engineering, Kunsan National University, 558 Daehak-ro, Gunsan, Jeollabuk-do 573-701, Republic of Korea.
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Lee SC. Application of Emulsion Liquid Membrane to Removal of Fermentation Inhibitors from Simulated Hemicellulosic Hydrolysates. KOREAN CHEMICAL ENGINEERING RESEARCH 2015. [DOI: 10.9713/kcer.2015.53.4.457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kannisto MS, Mangayil RK, Shrivastava-Bhattacharya A, Pletschke BI, Karp MT, Santala VP. Metabolic engineering of Acinetobacter baylyi ADP1 for removal of Clostridium butyricum growth inhibitors produced from lignocellulosic hydrolysates. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:198. [PMID: 26628912 PMCID: PMC4666034 DOI: 10.1186/s13068-015-0389-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 11/16/2015] [Indexed: 05/05/2023]
Abstract
BACKGROUND Pretreatment of lignocellulosic biomass can produce inhibitory compounds that are harmful for microorganisms used in the production of biofuels and other chemicals from lignocellulosic sugars. Selective inhibitor removal can be achieved with biodetoxification where microorganisms catabolize the inhibitors without consuming the sugars. We engineered the strictly aerobic Acinetobacter baylyi ADP1 for detoxification of lignocellulosic hydrolysates by removing the gene for glucose dehydrogenase, gcd, which catalyzes the first step in its glucose catabolism. RESULTS The engineered A. baylyi ADP1 strain was shown to be incapable of consuming the main sugar components of lignocellulosic hydrolysates, i.e., glucose, xylose, and arabinose, but rapidly utilized acetate and formate. Formate was consumed during growth on acetate and by stationary phase cells, and this was enhanced in the presence of a common aromatic inhibitor of lignocellulosic hydrolysates, 4-hydroxybenzoate. The engineered strain tolerated glucose well up to 70 g/l, and the consumption of glucose, xylose, or arabinose was not observed in prolonged cultivations. The engineered strain was applied in removal of oxygen, a gaseous inhibitor of anaerobic fermentations. Co-cultivation with the A. baylyi ADP1 gcd knockout strain under initially aerobic conditions allowed the strictly anaerobic Clostridium butyricum to grow and produce hydrogen (H2) from sugars of the enzymatic rice straw hydrolysate. CONCLUSIONS We demonstrated that the model organism of bacterial genetics and metabolism, A. baylyi ADP1, could be engineered to be an efficient biodetoxification strain of lignocellulosic hydrolysates. Only one gene knockout was required to completely eliminate sugar consumption and the strain could be used in production of anaerobic conditions for the strictly anaerobic hydrogen producer, C. butyricum. Because of these encouraging results, we believe that A. baylyi ADP1 is a promising candidate for the detoxification of lignocellulosic hydrolysates for bioprocesses.
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Affiliation(s)
- Matti S. Kannisto
- />Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland
| | - Rahul K. Mangayil
- />Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland
| | | | - Brett I. Pletschke
- />Department of Biochemistry and Microbiology, Enzyme Synergy Programme, Rhodes University, Grahamstown, 6140 South Africa
| | - Matti T. Karp
- />Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland
| | - Ville P. Santala
- />Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, Finland
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Shaw AJ, Miller BB, Rogers SR, Kenealy WR, Meola A, Bhandiwad A, Sillers WR, Shikhare I, Hogsett DA, Herring CD. Anaerobic detoxification of acetic acid in a thermophilic ethanologen. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:75. [PMID: 27279899 PMCID: PMC4898469 DOI: 10.1186/s13068-015-0257-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 04/24/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND The liberation of acetate from hemicellulose negatively impacts fermentations of cellulosic biomass, limiting the concentrations of substrate that can be effectively processed. Solvent-producing bacteria have the capacity to convert acetate to the less toxic product acetone, but to the best of our knowledge, this trait has not been transferred to an organism that produces ethanol at high yield. RESULTS We have engineered a five-step metabolic pathway to convert acetic acid to acetone in the thermophilic anaerobe Thermoanaerobacterium saccharolyticum. The first steps of the pathway, a reversible conversion of acetate to acetyl-CoA, are catalyzed by the native T. saccharolyticum enzymes acetate kinase and phosphotransacetylase. ack and pta normally divert 30% of catabolic carbon flux to acetic acid; however, their re-introduction in evolved ethanologen strains resulted in virtually no acetic acid production. Conversion between acetic acid and acetyl-CoA remained active, as evidenced by rapid (13)C label transfer from exogenous acetate to ethanol. Genomic re-sequencing of six independently evolved ethanologen strains showed convergent mutations in the hfs hydrogenase gene cluster, which when transferred to wildtype T. saccharolyticum conferred a low acid production phenotype. Thus, the mutated hfs genes effectively separate acetic acid production and consumption from central metabolism, despite their intersecting at the common intermediate acetyl-CoA. To drive acetic acid conversion to a less inhibitory product, the enzymes thiolase, acetoacetate:acetate CoA-transferase, and acetoacetate decarboxylase were assembled in T. saccharolyticum with genes from thermophilic donor organisms that do not natively produce acetone. The resultant strain converted acetic acid to acetone and ethanol while maintaining a metabolic yield of 0.50 g ethanol per gram carbohydrate. CONCLUSIONS Conversion of acetic acid to acetone results in improved ethanol productivity and titer and is an attractive low-cost solution to acetic acid inhibition.
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Affiliation(s)
- A Joe Shaw
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Novogy Inc., 85 Bolton St, Cambridge, MA 02140 USA
| | | | | | - William R Kenealy
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Verdezyne Inc., 2715 Loker Avenue West, Carlsbad, CA 92010 USA
| | - Alex Meola
- />Mascoma Corporation, Lebanon, NH 03766 USA
| | - Ashwini Bhandiwad
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
- />Energy Biosciences Institute, 2151 Berkeley Way, Berkeley, CA 94704 USA
| | - W Ryan Sillers
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Myriant Corporation, 66 Cummings Park, Woburn, MA 01801 USA
| | | | - David A Hogsett
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />OPX Biotechnologies Inc., 2425 55th Street, Boulder, CO 80301 USA
| | - Christopher D Herring
- />Mascoma Corporation, Lebanon, NH 03766 USA
- />Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 USA
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Lee SC. Purification of xylose in simulated hemicellulosic hydrolysates using a two-step emulsion liquid membrane process. BIORESOURCE TECHNOLOGY 2014; 169:692-699. [PMID: 25108268 DOI: 10.1016/j.biortech.2014.07.067] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 07/05/2014] [Accepted: 07/17/2014] [Indexed: 06/03/2023]
Abstract
Purification of xylose in simulated hemicellulosic hydrolysates was attempted using a two-step emulsion liquid membrane (ELM) process. The effects of various experimental variables on extraction of each component in the hydrolysates were investigated in the ELM steps. In the first ELM step, acetic acid could be selectively removed from the hydrolysates and highly enriched in the stripping phase, and loss of xylose was insignificant. In the second ELM step, sulfuric acid could be selectively removed from simulated acetic acid-free hemicellulosic hydrolysates and somewhat enriched in the stripping phase. There was just small loss of xylose, and the final pH of the feed phase approached a pH level suitable for ethanol fermentation. Also, concentration of xylose in the feed phase was attained as an incidental outcome during each ELM run. Conclusively, the two-step ELM process was found to be a promising futuristic technology for purification of sugars in real hemicellulosic hydrolysates.
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Affiliation(s)
- Sang Cheol Lee
- Department of Chemical Engineering, Kunsan National University, 558 Daehak-ro, Kunsan, Chonbuk 573-701, Republic of Korea.
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Henson MA, Hanly TJ. Dynamic flux balance analysis for synthetic microbial communities. IET Syst Biol 2014; 8:214-29. [PMID: 25257022 PMCID: PMC8687154 DOI: 10.1049/iet-syb.2013.0021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/10/2013] [Accepted: 12/11/2013] [Indexed: 01/14/2023] Open
Abstract
Dynamic flux balance analysis (DFBA) is an extension of classical flux balance analysis that allows the dynamic effects of the extracellular environment on microbial metabolism to be predicted and optimised. Recently this computational framework has been extended to microbial communities for which the individual species are known and genome-scale metabolic reconstructions are available. In this review, the authors provide an overview of the emerging DFBA approach with a focus on two case studies involving the conversion of mixed hexose/pentose sugar mixtures by synthetic microbial co-culture systems. These case studies illustrate the key requirements of the DFBA approach, including the incorporation of individual species metabolic reconstructions, formulation of extracellular mass balances, identification of substrate uptake kinetics, numerical solution of the coupled linear program/differential equations and model adaptation for common, suboptimal growth conditions and identified species interactions. The review concludes with a summary of progress to date and possible directions for future research.
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Affiliation(s)
- Michael A Henson
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA.
| | - Timothy J Hanly
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01007, USA
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Moreno AD, Ibarra D, Alvira P, Tomás-Pejó E, Ballesteros M. A review of biological delignification and detoxification methods for lignocellulosic bioethanol production. Crit Rev Biotechnol 2014; 35:342-54. [DOI: 10.3109/07388551.2013.878896] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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12
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Hanly TJ, Henson MA. Dynamic model-based analysis of furfural and HMF detoxification by pure and mixed batch cultures of S. cerevisiae and S. stipitis. Biotechnol Bioeng 2013; 111:272-84. [PMID: 23983023 DOI: 10.1002/bit.25101] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 08/13/2013] [Accepted: 08/15/2013] [Indexed: 01/16/2023]
Abstract
Inhibitory compounds that result from biomass hydrolysis are an obstacle to the efficient production of second-generation biofuels. Fermentative microorganisms can reduce compounds such as furfural and 5-hydroxymethyl furfural (HMF), but detoxification is accompanied by reduced growth rates and ethanol yields. In this study, we assess the effects of these furan aldehydes on pure and mixed yeast cultures consisting of a respiratory deficient mutant of Saccharomyces cerevisiae and wild-type Scheffersomyces stipitis using dynamic flux balance analysis. Uptake kinetics and stoichiometric equations for the intracellular reduction reactions associated with each inhibitor were added to genome-scale metabolic reconstructions of the two yeasts. Further modification of the S. cerevisiae metabolic network was necessary to satisfactorily predict the amount of acetate synthesized during HMF reduction. Inhibitory terms that captured the adverse effects of the furan aldehydes and their corresponding alcohols on cell growth and ethanol production were added to attain qualitative agreement with batch experiments conducted for model development and validation. When the two yeasts were co-cultured in the presence of the furan aldehydes, inoculums that reduced the synthesis of highly toxic acetate produced by S. cerevisiae yielded the highest ethanol productivities. The model described here can be used to generate optimal fermentation strategies for the simultaneous detoxification and fermentation of lignocellulosic hydrolysates by S. cerevisiae and/or S. stipitis.
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Affiliation(s)
- Timothy J Hanly
- Department of Chemical Engineering, University of Massachusetts, Goessmann Lab 159, 686 N. Pleasant St., Amherst, Massachusetts, 01003-3110
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Development of an emulsion liquid membrane system for removal of acetic acid from xylose and sulfuric acid in a simulated hemicellulosic hydrolysate. Sep Purif Technol 2013. [DOI: 10.1016/j.seppur.2013.07.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Fatehi P. Recent advancements in various steps of ethanol, butanol, and isobutanol productions from woody materials. Biotechnol Prog 2013; 29:297-310. [DOI: 10.1002/btpr.1688] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 11/30/2012] [Indexed: 01/24/2023]
Affiliation(s)
- Pedram Fatehi
- Chemical Engineering Dept.; Lakehead University; Thunder Bay ON Canada P7B5E1
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Zhang D, Ong YL, Li Z, Wu JC. Biological detoxification of furfural and 5-hydroxyl methyl furfural in hydrolysate of oil palm empty fruit bunch by Enterobacter sp. FDS8. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2013.01.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yu Y, Feng Y, Xu C, Liu J, Li D. Onsite bio-detoxification of steam-exploded corn stover for cellulosic ethanol production. BIORESOURCE TECHNOLOGY 2011; 102:5123-5128. [PMID: 21334878 DOI: 10.1016/j.biortech.2011.01.067] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 01/19/2011] [Accepted: 01/20/2011] [Indexed: 05/27/2023]
Abstract
In the process of ethanol production from steam-exploded corn stover (SECS), a cellulose-degradation strain of Aspergillus nidulans (FLZ10) was investigated whether it could remove the inhibitors released from steam exploded pretreatment , and thereby be used for biological detoxification on Saccharomycescerevisiae. The results showed that FLZ10 removed 75.2% formic acid, 53.6% acetic acid, and 100% hydroxymethyl furfural (5-HMF) and furfural from the hydrolysate washed from SECS after 72h cultivation. A cellulase activity of 0.49 IU/ml was simultaneously produced while the biological detoxification occurred. An ethanol yield of 0.45 g/g on glucose was obtained in the hydrolysate biodetoxified by FLZ10. The glucose consumption rate of FLZ10 was much lower than that of S. cerevisiae, thereby it had little competition with S. cerevisiae on glucose consumption. Based on SECS to ethanol mass balance analysis, with the onsite bio-detoxification, fermentation using S. cerevisiae effectively converted monomeric glucose with 94.4% ethanol yield.
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Affiliation(s)
- Yanling Yu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No 73 Huanghe Road, Nangang District, Harbin 150090, China
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Microbial removal of acetate selectively from sugar mixtures. J Ind Microbiol Biotechnol 2011; 38:1477-84. [PMID: 21225311 DOI: 10.1007/s10295-010-0932-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 12/18/2010] [Indexed: 10/18/2022]
Abstract
Acetic acid is an unavoidable constituent of the biomass hydrolysates generated from acetylated hemicellulose and lignin, and acetate affects the performance of microbes used to convert these hydrolysates into biofuels or other biochemicals. In this study, acetate was selectively removed from synthetic mixtures of glucose and xylose using metabolically engineered Escherichia coli strains having mutations in the glucose phosphotransferase system (PTS) genes (ptsG, manZ, crr), glucokinase (glk), and xylose (xylA). In batch culture, ALS1060 (ptsG manZ glk xylA) consumed exclusively acetate to depletion, and then consumed the two sugars only at a very slow rate (a growth rate of about 0.01 h(-1)). We also examined the effects of an additional knockout of either malX, fruA, fruB, bglF, or crr, genes that are involved in other PTSs, and a batch process using KD840 (ptsG manZ glk crr xylA) demonstrated a further reduction in glucose or xylose consumption by E. coli. These results demonstrate the feasibility of using a substrate-selective approach for the pre-treatment of biomass hydrolysate for microbial processes.
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Affiliation(s)
- Pedram Fatehi
- Chemical Engineering Department and Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3
| | - Yonghao Ni
- Chemical Engineering Department and Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3
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Parawira W, Tekere M. Biotechnological strategies to overcome inhibitors in lignocellulose hydrolysates for ethanol production: review. Crit Rev Biotechnol 2010; 31:20-31. [DOI: 10.3109/07388551003757816] [Citation(s) in RCA: 301] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Keating JD, Robinson J, Cotta MA, Saddler JN, Mansfield SD. An ethanologenic yeast exhibiting unusual metabolism in the fermentation of lignocellulosic hexose sugars. J Ind Microbiol Biotechnol 2004; 31:235-44. [PMID: 15252719 DOI: 10.1007/s10295-004-0145-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Accepted: 03/26/2004] [Indexed: 11/24/2022]
Abstract
Three lignocellulosic substrate mixtures [liquid fraction of acid-catalyzed steam-exploded softwood, softwood spent sulfite liquor (SSL) and hardwood SSL] were separately fermented by the industrially employed SSL-adapted strain Tembec T1 and a natural galactose-assimilating isolate (Y-1528) of Saccharomyces cerevisiae to compare fermentative efficacy. Both strains were confirmed as S. cerevisiae via molecular genotyping. The performance of strain Y-1528 exceeded that of Tembec T1 on all three substrate mixtures, with complete hexose sugar consumption ranging from 10 to 18 h for Y-1528, vs 24 to 28 h for T1. Furthermore, Y-1528 consumed galactose prior to glucose and mannose, in contrast to Tembec T1, which exhibited catabolite repression of galactose metabolism. Ethanol yields were comparable regardless of the substrate utilized. Strains T1 and Y-1528 were also combined in mixed culture to determine the effects of integrating their distinct metabolic capabilities during defined hexose sugar and SSL fermentations. Sugar consumption in the defined mixture was accelerated, with complete exhaustion of hexose sugars occurring in just over 6 h. Galactose was consumed first, followed by glucose and mannose. Ethanol yields were slightly reduced relative to pure cultures of Y-1528, but normal growth kinetics was not impeded. Sugar consumption in the SSLs was also accelerated, with complete utilization of softwood- and hardwood-derived hexose sugars occurring in 6 and 8 h, respectively. Catabolite repression was absent in both SSL fermentations.
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Affiliation(s)
- J D Keating
- Forest Products Biotechnology, Department of Wood Science, University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada, V6T 1Z4
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Cruz JM, Domı́nguez JM, Domı́nguez H, Parajó JC. Solvent extraction of hemicellulosic wood hydrolysates: a procedure useful for obtaining both detoxified fermentation media and polyphenols with antioxidant activity. Food Chem 1999. [DOI: 10.1016/s0308-8146(99)00106-5] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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