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Use of proteomic analysis to elucidate the role of calcium in acetone-butanol-ethanol fermentation by Clostridium beijerinckii NCIMB 8052. Appl Environ Microbiol 2012; 79:282-93. [PMID: 23104411 DOI: 10.1128/aem.02969-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Calcium carbonate increases growth, substrate utilization, and acetone-butanol-ethanol (ABE) fermentation by Clostridium beijerinckii NCIMB 8052. Toward an understanding of the basis for these pleiotropic effects, we profiled changes in the C. beijerinckii NCIMB 8052 proteome that occur in response to the addition of CaCO(3). We observed increases in the levels of different heat shock proteins (GrpE and DnaK), sugar transporters, and proteins involved in DNA synthesis, repair, recombination, and replication. We also noted significant decreases in the levels of proteins involved in metabolism, nucleic acid stabilization, sporulation, oxidative and antibiotic stress responses, and signal transduction. We determined that CaCO(3) enhances ABE fermentation due to both its buffering effects and its ability to influence key cellular processes, such as sugar transport, butanol tolerance, and solventogenesis. Moreover, activity assays in vitro for select solventogenic enzymes revealed that part of the underpinning for the CaCO(3)-mediated increase in the level of ABE fermentation stems from the enhanced activity of these catalysts in the presence of Ca(2+). Collectively, these proteomic and biochemical studies provide new insights into the multifactorial basis for the stimulation of ABE fermentation and butanol tolerance in the presence of CaCO(3).
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102
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Setlhaku M, Brunberg S, Villa EDA, Wichmann R. Improvement in the bioreactor specific productivity by coupling continuous reactor with repeated fed-batch reactor for acetone–butanol–ethanol production. J Biotechnol 2012; 161:147-52. [DOI: 10.1016/j.jbiotec.2012.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 04/05/2012] [Accepted: 04/10/2012] [Indexed: 01/19/2023]
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103
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Zhang WL, Liu ZY, Liu Z, Li FL. Butanol production from corncob residue using Clostridium beijerinckii NCIMB 8052. Lett Appl Microbiol 2012; 55:240-6. [PMID: 22738279 DOI: 10.1111/j.1472-765x.2012.03283.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To determine whether corncob residue (CCR) could be a good substrate for butanol production. METHODS AND RESULTS In this study, Ca(OH)₂ detoxification technique was used to remove inhibitors of lignocellulose enzymatic hydrolysis. During fermentation of untreated corncob residue hydrolysate (CCRH) by Clostridium beijerinckii NCIMB 8052, cell growth was inhibited and only 3·8 g l⁻¹ acetone, butanol and ethanol (ABE) was produced. After pretreatment with Ca(OH)₂, enzymatic hydrolysis of CCR resulted in 49·3 g l⁻¹ total sugars, about twofold of that of untreated one. In the fermentation of the Ca(OH)₂-detoxified CCRH, sugar utilization ratio was increased by 27·3%. When using the Ca(OH)₂-detoxified CCRH supplemented with 10 g l⁻¹ glucose, 16·0 g l⁻¹ ABE was produced, resulting in an ABE yield of 0·32 and a productivity of 0·33 g l⁻¹ h⁻¹. CONCLUSION The results in this study suggest that CCR was a good carbon source for ABE fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY It is the first time to use CCR as substrate for butanol production. Ca(OH)₂ detoxification pretreatment was proved to be an effective method to improve enzymatic digestibility of lignocellulose.
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Affiliation(s)
- W L Zhang
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China Graduate University of Chinese Academy of Sciences, Beijing, China
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104
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Qureshi N, Bowman M, Saha B, Hector R, Berhow M, Cotta M. Effect of cellulosic sugar degradation products (furfural and hydroxymethyl furfural) on acetone–butanol–ethanol (ABE) fermentation using Clostridium beijerinckii P260. FOOD AND BIOPRODUCTS PROCESSING 2012. [DOI: 10.1016/j.fbp.2011.09.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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105
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Pretreatment of switchgrass with electrolyzed water and a two-stage method for bioethanol production. BIOTECHNOL BIOPROC E 2012. [DOI: 10.1007/s12257-011-0583-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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106
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Lee S, Nam D, Jung JY, Oh MK, Sang BI, Mitchell RJ. Identification of Escherichia coli biomarkers responsive to various lignin-hydrolysate compounds. BIORESOURCE TECHNOLOGY 2012; 114:450-456. [PMID: 22445268 DOI: 10.1016/j.biortech.2012.02.085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 05/31/2023]
Abstract
Aberrations in the growth and transcriptome of Escherichia coli str. BL21(DE3) were determined when exposed to varying concentrations of ferulic acid (0.25-1 g/L), an aromatic carboxylic acid identified within lignin-cellulose hydrolysate samples. The expression of several individual genes (aaeA, aaeB, inaA and marA) was significantly induced, i.e., more than 4-fold, and thus these genes and the heat shock response gene htpG were selected as biomarkers to monitor E. coli's responses to five additional hydrolysate-related compounds, including vanillic acid, coumaric acid, 4-hydroxybenzoic acid, ferulaldehyde and furfural. While all of the biomarkers showed dose-dependent responses to most of the compounds, expression of aaeA and aaeB showed the greatest induction (5-30-fold) for all compounds tested except furfural. Lastly, the marA, inaA and htpG genes all showed higher expression levels when the culture was exposed to spruce hydrolysate samples, demonstrating the potential use of these genes as biomarkers.
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Affiliation(s)
- Siseon Lee
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, 100 Banyeon-ri, Eonyang-eup, Ulsan 689-805, Republic of Korea
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Tracy BP, Jones SW, Fast AG, Indurthi DC, Papoutsakis ET. Clostridia: the importance of their exceptional substrate and metabolite diversity for biofuel and biorefinery applications. Curr Opin Biotechnol 2012; 23:364-81. [DOI: 10.1016/j.copbio.2011.10.008] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/06/2011] [Accepted: 10/20/2011] [Indexed: 12/19/2022]
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108
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Lee SS, Monnappa AK, Mitchell RJ. Biological activities of lignin hydrolysate-related compounds. BMB Rep 2012; 45:265-74. [DOI: 10.5483/bmbrep.2012.45.5.265] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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109
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Jurgens G, Survase S, Berezina O, Sklavounos E, Linnekoski J, Kurkijärvi A, Väkevä M, van Heiningen A, Granström T. Butanol production from lignocellulosics. Biotechnol Lett 2012; 34:1415-34. [PMID: 22526420 DOI: 10.1007/s10529-012-0926-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 03/27/2012] [Indexed: 12/20/2022]
Abstract
Clostridium spp. produce n-butanol in the acetone/butanol/ethanol process. For sustainable industrial scale butanol production, a number of obstacles need to be addressed including choice of feedstock, the low product yield, toxicity to production strain, multiple-end products and downstream processing of alcohol mixtures. This review describes the use of lignocellulosic feedstocks, bioprocess and metabolic engineering, downstream processing and catalytic refining of n-butanol.
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Affiliation(s)
- German Jurgens
- Department of Biotechnology and Chemical Technology, Aalto University, 00076, Espoo, Finland.
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110
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Wang Y, Li X, Mao Y, Blaschek HP. Genome-wide dynamic transcriptional profiling in Clostridium beijerinckii NCIMB 8052 using single-nucleotide resolution RNA-Seq. BMC Genomics 2012; 13:102. [PMID: 22433311 PMCID: PMC3395874 DOI: 10.1186/1471-2164-13-102] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 03/20/2012] [Indexed: 12/31/2022] Open
Abstract
Background Clostridium beijerinckii is a prominent solvent-producing microbe that has great potential for biofuel and chemical industries. Although transcriptional analysis is essential to understand gene functions and regulation and thus elucidate proper strategies for further strain improvement, limited information is available on the genome-wide transcriptional analysis for C. beijerinckii. Results The genome-wide transcriptional dynamics of C. beijerinckii NCIMB 8052 over a batch fermentation process was investigated using high-throughput RNA-Seq technology. The gene expression profiles indicated that the glycolysis genes were highly expressed throughout the fermentation, with comparatively more active expression during acidogenesis phase. The expression of acid formation genes was down-regulated at the onset of solvent formation, in accordance with the metabolic pathway shift from acidogenesis to solventogenesis. The acetone formation gene (adc), as a part of the sol operon, exhibited highly-coordinated expression with the other sol genes. Out of the > 20 genes encoding alcohol dehydrogenase in C. beijerinckii, Cbei_1722 and Cbei_2181 were highly up-regulated at the onset of solventogenesis, corresponding to their key roles in primary alcohol production. Most sporulation genes in C. beijerinckii 8052 demonstrated similar temporal expression patterns to those observed in B. subtilis and C. acetobutylicum, while sporulation sigma factor genes sigE and sigG exhibited accelerated and stronger expression in C. beijerinckii 8052, which is consistent with the more rapid forespore and endspore development in this strain. Global expression patterns for specific gene functional classes were examined using self-organizing map analysis. The genes associated with specific functional classes demonstrated global expression profiles corresponding to the cell physiological variation and metabolic pathway switch. Conclusions The results from this work provided insights for further C. beijerinckii strain improvement employing system biology-based strategies and metabolic engineering approaches.
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Affiliation(s)
- Yi Wang
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 61801, USA
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111
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Lee S, Mitchell RJ. Detection of toxic lignin hydrolysate-related compounds using an inaA::luxCDABE fusion strain. J Biotechnol 2012; 157:598-604. [DOI: 10.1016/j.jbiotec.2011.06.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 06/15/2011] [Accepted: 06/17/2011] [Indexed: 10/18/2022]
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112
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Lu C, Zhao J, Yang ST, Wei D. Fed-batch fermentation for n-butanol production from cassava bagasse hydrolysate in a fibrous bed bioreactor with continuous gas stripping. BIORESOURCE TECHNOLOGY 2012; 104:380-7. [PMID: 22101071 DOI: 10.1016/j.biortech.2011.10.089] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 10/23/2011] [Accepted: 10/24/2011] [Indexed: 05/23/2023]
Abstract
Concentrated cassava bagasse hydrolysate (CBH) containing 584.4 g/L glucose was studied for acetone-butanol-ethanol (ABE) fermentation with a hyper-butanol-producing Clostridium acetobutylicum strain in a fibrous bed bioreactor with gas stripping for continuous butanol recovery. With periodical nutrient supplementation, stable production of n-butanol from glucose in the CBH was maintained in the fed-batch fermentation over 263 h with an average sugar consumption rate of 1.28 g/L h and butanol productivity of 0.32±0.03 g/L h. A total of 108.5 g/L ABE (butanol: 76.4 g/L, acetone: 27.0 g/L, ethanol: 5.1 g/L) was produced, with an overall yield of 0.32±0.03 g/g glucose for ABE and 0.23±0.01 g/g glucose for butanol. The gas stripping process generated a product containing 10-16% (w/v) of butanol, ~4% (w/v) of acetone, a small amount of ethanol (<0.8%) and almost no acids, resulting in a highly concentrated butanol solution of ~64% (w/v) after phase separation.
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Affiliation(s)
- Congcong Lu
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 W. 19th Ave., Columbus, OH 43210, USA
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113
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Napoli F, Olivieri G, Russo ME, Marzocchella A, Salatino P. Continuous lactose fermentation by Clostridium acetobutylicum--assessment of energetics and product yields of the acidogenesis. Enzyme Microb Technol 2011; 50:165-72. [PMID: 22305171 DOI: 10.1016/j.enzmictec.2011.11.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 11/13/2011] [Indexed: 11/19/2022]
Abstract
An assessment of both the growth and the metabolism of acidogenic cells Clostridium acetobutylicum DSM 792 is reported in the paper. Tests were carried out in a CSTR under controlled pH conditions. Cultures were carried out using a semi-synthetic medium supplemented with lactose as carbon source. Acids and solvents, that represent products of the ABE process, have been purposely added in controlled amounts to the culture medium to investigate their effects on the product yields. The mass fractional yield of biomass and products were expressed as a function of the specific growth rate taking into account the Pirt model. The maximum ATP yield and the maintenance resulted 29.1 g(DM)/mol(ATP) and 0.012 mol(ATP)/g(DM)h, respectively. Quantitative features of the C. acetobutylicum growth model were in good agreement with experimental results. The model proposes as a tool to estimate the mass fractional yield even for fermentations carried out under conditions typical of the solventogenesis.
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Affiliation(s)
- Fabio Napoli
- Chemical Engineering Department, Università degli Studi di Napoli Federico II, P.le V. Tecchio n. 80, 80125 Napoli, Italy
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114
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Continuous bio-catalytic conversion of sugar mixture to acetone–butanol–ethanol by immobilized Clostridium acetobutylicum DSM 792. Appl Microbiol Biotechnol 2011; 93:2309-16. [DOI: 10.1007/s00253-011-3761-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/10/2011] [Accepted: 11/12/2011] [Indexed: 10/14/2022]
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115
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Survase SA, Sklavounos E, Jurgens G, van Heiningen A, Granström T. Continuous acetone-butanol-ethanol fermentation using SO2-ethanol-water spent liquor from spruce. BIORESOURCE TECHNOLOGY 2011; 102:10996-11002. [PMID: 21974878 DOI: 10.1016/j.biortech.2011.09.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 05/31/2023]
Abstract
SO2-ethanol-water (SEW) spent liquor from spruce chips was successfully used for batch and continuous production of acetone, butanol and ethanol (ABE). Initially, batch experiments were performed using spent liquor to check the suitability for production of ABE. Maximum concentration of total ABE was found to be 8.79 g/l using 4-fold diluted SEW liquor supplemented with 35 g/l of glucose. The effect of dilution rate on solvent production, productivity and yield was studied in column reactor consisting of immobilized Clostridium acetobutylicum DSM 792 on wood pulp. Total solvent concentration of 12 g/l was obtained at a dilution rate of 0.21 h(-1). The maximum solvent productivity (4.86 g/l h) with yield of 0.27 g/g was obtained at dilution rate of 0.64 h(-1). Further, to increase the solvent yield, the unutilized sugars were subjected to batch fermentation.
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Affiliation(s)
- Shrikant A Survase
- Aalto University School of Chemical Technology, Department of Biotechnology and Chemical Technology, POB 16100, 00076 Aalto, Finland.
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116
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Wang Y, Blaschek HP. Optimization of butanol production from tropical maize stalk juice by fermentation with Clostridium beijerinckii NCIMB 8052. BIORESOURCE TECHNOLOGY 2011; 102:9985-90. [PMID: 21893411 DOI: 10.1016/j.biortech.2011.08.038] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 08/07/2011] [Accepted: 08/09/2011] [Indexed: 05/16/2023]
Abstract
Mixed sugars from tropical maize stalk juice were used to carry out butanol fermentation with Clostridium beijerinckii NCIMB 8052. Batch experiments employing central composite design (CCD) and response surface methodology (RSM) optimization were performed to evaluate effects of three factors, i.e. pH, initial total sugar concentration, and agitation rate on butanol production. Optimum conditions of pH 6.7, sugar concentration 42.2g/L and agitation rate 48 rpm were predicted, under which a maximum butanol yield of 0.27 g/g-sugar was estimated. Further experiments demonstrated that higher agitation facilitated acetone production, leading to lower butanol selectivity in total acetone-butanol-ethanol (ABE). While glucose and fructose are more preferable by C. beijerinckii, sucrose can also be easily degraded by the microorganism. This study indicated that RSM is a useful approach for optimizing operational conditions for butanol production, and demonstrated that tropical maize, with high yield of biomass and stalk sugars, is a promising biofuel crop.
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Affiliation(s)
- Yi Wang
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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117
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Comparative shotgun proteomic analysis of Clostridium acetobutylicum from butanol fermentation using glucose and xylose. Proteome Sci 2011; 9:66. [PMID: 22008648 PMCID: PMC3212805 DOI: 10.1186/1477-5956-9-66] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 10/18/2011] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Butanol is a second generation biofuel produced by Clostridium acetobutylicum through acetone-butanol-ethanol (ABE) fermentation process. Shotgun proteomics provides a direct approach to study the whole proteome of an organism in depth. This paper focuses on shotgun proteomic profiling of C. acetobutylicum from ABE fermentation using glucose and xylose to understand the functional mechanisms of C. acetobutylicum proteins involved in butanol production. RESULTS We identified 894 different proteins in C. acetobutylicum from ABE fermentation process by two dimensional - liquid chromatography - tandem mass spectrometry (2D-LC-MS/MS) method. This includes 717 proteins from glucose and 826 proteins from the xylose substrate. A total of 649 proteins were found to be common and 22 significantly differentially expressed proteins were identified between glucose and xylose substrates. CONCLUSION Our results demonstrate that flagellar proteins are highly up-regulated with glucose compared to xylose substrate during ABE fermentation. Chemotactic activity was also found to be lost with the xylose substrate due to the absence of CheW and CheV proteins. This is the first report on the shotgun proteomic analysis of C. acetobutylicum ATCC 824 in ABE fermentation between glucose and xylose substrate from a single time data point and the number of proteins identified here is more than any other study performed on this organism up to this report.
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118
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Bramono SE, Lam YS, Ong SL, He J. A mesophilic Clostridium species that produces butanol from monosaccharides and hydrogen from polysaccharides. BIORESOURCE TECHNOLOGY 2011; 102:9558-63. [PMID: 21852120 DOI: 10.1016/j.biortech.2011.07.077] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 05/10/2023]
Abstract
A unique mesophilic Clostridium species strain BOH3 is obtained in this study, which is capable of fermenting monosaccharides to produce butanol and hydrolyzing polysaccharides to produce hydrogen (H(2)) and volatile fatty acids (VFAs). From 30 g/L of glucose and xylose each, batch culture BOH3 was able to produce 4.67 and 4.63 g/L of butanol. Enhancement treatments by increasing the inoculated cells improved butanol production to 7.05 and 7.41 g/L, respectively. Hydrogen production (2.47 and 1.93 mmol) was observed when cellulose and xylan (10 g/L each) were used, suggesting that strain BOH3 possesses xylanolytic and cellulolytic capabilities. These unique features reveal the strain's novelty as most wild-type solventogenic strains have not been reported to have such properties. Therefore, culture BOH3 is promising in generating butanol and hydrogen from renewable feedstock.
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Affiliation(s)
- Sandhi Eko Bramono
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore 117576, Singapore
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119
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Wang Y, Li X, Mao Y, Blaschek HP. Single-nucleotide resolution analysis of the transcriptome structure of Clostridium beijerinckii NCIMB 8052 using RNA-Seq. BMC Genomics 2011; 12:479. [PMID: 21962126 PMCID: PMC3271303 DOI: 10.1186/1471-2164-12-479] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 09/30/2011] [Indexed: 12/02/2022] Open
Abstract
Background Clostridium beijerinckii is an important solvent producing microorganism. The genome of C. beijerinckii NCIMB 8052 has recently been sequenced. Although transcriptome structure is important in order to reveal the functional and regulatory architecture of the genome, the physical structure of transcriptome for this strain, such as the operon linkages and transcript boundaries are not well understood. Results In this study, we conducted a single-nucleotide resolution analysis of the C. beijerinckii NCIMB 8052 transcriptome using high-throughput RNA-Seq technology. We identified the transcription start sites and operon structure throughout the genome. We confirmed the structure of important gene operons involved in metabolic pathways for acid and solvent production in C. beijerinckii 8052, including pta-ack, ptb-buk, hbd-etfA-etfB-crt (bcs) and ald-ctfA-ctfB-adc (sol) operons; we also defined important operons related to chemotaxis/motility, transcriptional regulation, stress response and fatty acids biosynthesis along with others. We discovered 20 previously non-annotated regions with significant transcriptional activities and 15 genes whose translation start codons were likely mis-annotated. As a consequence, the accuracy of existing genome annotation was significantly enhanced. Furthermore, we identified 78 putative silent genes and 177 putative housekeeping genes based on normalized transcription measurement with the sequence data. We also observed that more than 30% of pseudogenes had significant transcriptional activities during the fermentation process. Strong correlations exist between the expression values derived from RNA-Seq analysis and microarray data or qRT-PCR results. Conclusions Transcriptome structural profiling in this research provided important supplemental information on the accuracy of genome annotation, and revealed additional gene functions and regulation in C. beijerinckii.
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Affiliation(s)
- Yi Wang
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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120
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Confirmation and elimination of xylose metabolism bottlenecks in glucose phosphoenolpyruvate-dependent phosphotransferase system-deficient Clostridium acetobutylicum for simultaneous utilization of glucose, xylose, and arabinose. Appl Environ Microbiol 2011; 77:7886-95. [PMID: 21926197 DOI: 10.1128/aem.00644-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Efficient cofermentation of D-glucose, D-xylose, and L-arabinose, three major sugars present in lignocellulose, is a fundamental requirement for cost-effective utilization of lignocellulosic biomass. The Gram-positive anaerobic bacterium Clostridium acetobutylicum, known for its excellent capability of producing ABE (acetone, butanol, and ethanol) solvent, is limited in using lignocellulose because of inefficient pentose consumption when fermenting sugar mixtures. To overcome this substrate utilization defect, a predicted glcG gene, encoding enzyme II of the D-glucose phosphoenolpyruvate-dependent phosphotransferase system (PTS), was first disrupted in the ABE-producing model strain Clostridium acetobutylicum ATCC 824, resulting in greatly improved D-xylose and L-arabinose consumption in the presence of D-glucose. Interestingly, despite the loss of GlcG, the resulting mutant strain 824glcG fermented D-glucose as efficiently as did the parent strain. This could be attributed to residual glucose PTS activity, although an increased activity of glucose kinase suggested that non-PTS glucose uptake might also be elevated as a result of glcG disruption. Furthermore, the inherent rate-limiting steps of the D-xylose metabolic pathway were observed prior to the pentose phosphate pathway (PPP) in strain ATCC 824 and then overcome by co-overexpression of the D-xylose proton-symporter (cac1345), D-xylose isomerase (cac2610), and xylulokinase (cac2612). As a result, an engineered strain (824glcG-TBA), obtained by integrating glcG disruption and genetic overexpression of the xylose pathway, was able to efficiently coferment mixtures of D-glucose, D-xylose, and L-arabinose, reaching a 24% higher ABE solvent titer (16.06 g/liter) and a 5% higher yield (0.28 g/g) compared to those of the wild-type strain. This strain will be a promising platform host toward commercial exploitation of lignocellulose to produce solvents and biofuels.
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Zhang Y, Han B, Ezeji TC. Biotransformation of furfural and 5-hydroxymethyl furfural (HMF) by Clostridium acetobutylicum ATCC 824 during butanol fermentation. N Biotechnol 2011; 29:345-51. [PMID: 21925629 DOI: 10.1016/j.nbt.2011.09.001] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 08/17/2011] [Accepted: 09/05/2011] [Indexed: 11/26/2022]
Abstract
The ability of fermenting microorganisms to tolerate furan aldehyde inhibitors (furfural and 5-hydroxymethyl furfural (HMF)) will enhance efficient bioconversion of lignocellulosic biomass hydrolysates to fuels and chemicals. The effect of furfural and HMF on butanol production by Clostridium acetobutylicum 824 was investigated. Whereas specific growth rates, μ, of C. acetobutylicum in the presence of furfural and HMF were in the range of 15-85% and 23-78%, respectively, of the uninhibited Control, μ increased by 8-15% and 23-38% following exhaustion of furfural and HMF in the bioreactor. Using high performance liquid chromatography and spectrophotometric assays, batch fermentations revealed that furfural and HMF were converted to furfuryl alcohol and 2,5-bis-hydroxymethylfuran, respectively, with specific conversion rates of 2.13g furfural and 0.50g HMF per g (biomass) per hour, by exponentially growing C. acetobutylicum. Biotransformation of these furans to lesser inhibitory compounds by C. acetobutylicum will probably enhance overall fermentation of lignocellulosic hydrolysates to butanol.
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Affiliation(s)
- Yan Zhang
- The Ohio State University, Department of Animal Sciences and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691, USA
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122
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Fermentative production of butanol—the industrial perspective. Curr Opin Biotechnol 2011; 22:337-43. [DOI: 10.1016/j.copbio.2011.02.004] [Citation(s) in RCA: 551] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2010] [Revised: 02/01/2011] [Accepted: 02/02/2011] [Indexed: 01/20/2023]
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123
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Continuous production of isopropanol and butanol using Clostridium beijerinckii DSM 6423. Appl Microbiol Biotechnol 2011; 91:1305-13. [DOI: 10.1007/s00253-011-3322-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/11/2011] [Accepted: 04/11/2011] [Indexed: 10/18/2022]
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124
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Ahn JH, Sang BI, Um Y. Butanol production from thin stillage using Clostridium pasteurianum. BIORESOURCE TECHNOLOGY 2011; 102:4934-7. [PMID: 21316947 DOI: 10.1016/j.biortech.2011.01.046] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 01/12/2011] [Accepted: 01/15/2011] [Indexed: 05/03/2023]
Abstract
The production of butanol from thin stillage by Clostridium pasteurianum DSM 525 was evaluated in the paper. At initial pH values ranging from 5.0 to 7.0 C. pasteurianum DSM 525 produced 6.2-7.2 g/L of butanol utilizing glycerol in thin stillage as the main carbon source, with yields of 0.32-0.44 g butanol produced/g glycerol consumed, which are higher than previously reported yields (e.g., 0.14-0.31 g butanol/g glycerol, Biebl, 2001). Lactic acid in the thin stillage acted as a buffering agent, maintaining the pH of the medium within a range of 5.7-6.1. Lactic acid was also utilized along with glycerol, enhancing butanol production (6.5 g/L butanol vs. 8.7 g/L butanol with 0 and 16 g/L lactic acid, respectively). These results demonstrate the feasibility of cost-effective butanol production using thin stillage as a nutrient-containing medium with a pH buffering capacity.
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Affiliation(s)
- Jae-Hyung Ahn
- Clean Energy Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791, Republic of Korea
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125
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Napoli F, Olivieri G, Russo ME, Marzocchella A, Salatino P. Continuous lactose fermentation by Clostridium acetobutylicum--assessment of acidogenesis kinetics. BIORESOURCE TECHNOLOGY 2011; 102:1608-1614. [PMID: 20889336 DOI: 10.1016/j.biortech.2010.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 09/01/2010] [Accepted: 09/02/2010] [Indexed: 05/29/2023]
Abstract
An assessment of the growth kinetics of acidogenic cells of Clostridium acetobutylicum DSM 792 is reported in the paper. Tests were carried out in a continuous stirred tank reactor under controlled conditions adopting a complex medium supplemented with lactose as carbon source to mimic cheese whey. The effects of acids (acetic and butyric), solvents (acetone, ethanol and butanol) and pH on the growth rate of acidogenic cells were assessed. The conversion process was characterized under steady-state conditions in terms of concentration of lactose, cells, acids, total organic carbon and pH. The growth kinetics was expressed by means of a multiple product inhibition and interacting model including a novel formulation to account for the role of pH. The model has the potential to predict microorganism growth rate under a broad interval of operating conditions, even those typical of solvents production.
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Affiliation(s)
- Fabio Napoli
- Chemical Engineering Department, Università degli Studi di Napoli Federico II, P.le V. Tecchio n. 80, 80125 Napoli, Italy
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126
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Servinsky MD, Kiel JT, Dupuy NF, Sund CJ. Transcriptional analysis of differential carbohydrate utilization by Clostridium acetobutylicum. Microbiology (Reading) 2010; 156:3478-3491. [DOI: 10.1099/mic.0.037085-0] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transcriptional analysis was performed on Clostridium acetobutylicum with the goal of identifying sugar-specific mechanisms for the transcriptional regulation of transport and metabolism genes. DNA microarrays were used to determine transcript levels from total RNA isolated from cells grown on media containing eleven different carbohydrates, including two pentoses (xylose, arabinose), four hexoses (glucose, mannose, galactose, fructose), four disaccharides (sucrose, lactose, maltose, cellobiose) and one polysaccharide (starch). Sugar-specific induction of many transport and metabolism genes indicates that these processes are regulated at the transcriptional level and are subject to carbon catabolite repression. The results show that C. acetobutylicum utilizes symporters and ATP-binding cassette (ABC) transporters for the uptake of pentose sugars, while disaccharides and hexoses are primarily taken up by phosphotransferase system (PTS) transporters and a gluconate : H+ (GntP) transporter. The transcription of some transporter genes was induced by specific sugars, while others were induced by a subset of the sugars tested. Sugar-specific transport roles are suggested, based on expression comparisons, for various transporters of the PTS, the ABC superfamily and members of the major facilitator superfamily (MFS), including the GntP symporter family and the glycoside-pentoside-hexuronide (GPH)-cation symporter family. Additionally, updates to the C. acetobutylicum genome annotation are proposed, including the identification of genes likely to encode proteins involved in the metabolism of arabinose and xylose via the pentose phosphate pathway.
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Affiliation(s)
- Matthew D. Servinsky
- U S Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
| | - James T. Kiel
- U S Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
| | - Nicole F. Dupuy
- U S Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
| | - Christian J. Sund
- U S Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783, USA
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127
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Utilization of dry distiller's grain and solubles as nutrient supplement in the simultaneous saccharification and ethanol fermentation at high solids loading of corn stover. Biotechnol Lett 2010; 33:273-6. [PMID: 20953669 DOI: 10.1007/s10529-010-0429-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 10/01/2010] [Indexed: 10/19/2022]
Abstract
Dry distiller's grain and solubles (DDGS) is a major by-product of corn-based ethanol production and is usually used as animal feed. Here, it was added to the simultaneous saccharification and ethanol fermentation (SSF) carried out at high solids loading of steam explosion pretreated corn stover using a mutant strain Saccharomyces cerevisiae DQ1. The performance of SSF process with DDGS was comparable to those using the expensive yeast extract supplementation. With 30% (w/w) solids plus the addition of cellulase and 1g DDGS l(-1), the final ethanol reached 55 g l(-1) (7% v/v). The results indicated that the expensive supplement of yeast extract could be replaced by DDGS.
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128
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129
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Dahman Y, Jayasuriya KE, Kalis M. Potential of biocellulose nanofibers production from agricultural renewable resources: preliminary study. Appl Biochem Biotechnol 2010; 162:1647-59. [PMID: 20358409 DOI: 10.1007/s12010-010-8946-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 03/08/2010] [Indexed: 11/25/2022]
Abstract
In the present preliminary study, we report results for the biocellulose nanofibres production by Gluconacetobacter xylinus. Production was examined by utilizing different feedstocks of single sugars and sugar mixtures with compositions similar to the acid hydrolyzates of different agriculture residues. Profiles for cell proliferation, sugar consumption, and the subsequent pH changes were thoroughly analyzed. Highest biocellulose production of 5.65 g/L was achieved in fructose medium with total sugar consumption of 95.57%. Moreover, the highest production using sugar mixtures was 5.2 g/L, which was achieved in feedstock with composition identical to the acid hydrolyzate of wheat straws. This represented the highest biocellulose yield of 17.72 g/g sugars compared with 14.77 g/g fructose. The lowest production of 1.1 and 1.75 g/L were obtained in xylose and glucose media, respectively, while sucrose and arabinose media achieved relatively higher production of 4.7 and 4.1 g/L, respectively. Deviation in pH of the fermentation broths from the optimum value of 4-5 generally had marked effect on biocellulose production with single sugars in feedstock. However, the final pH values recorded in the different sugar mixtures were approximately 3.3-3.4, which had lower effect on production hindrance. Analyzing profiles for sugars' concentrations and cell growth showed that large amount of the metabolized sugars were mainly utilized for bacterial cell growth and maintenance, rather than biocellulose production. This was clearly observed with single sugars of low production, while sugar consumption was rather utilized for biocellulose production with sugar mixtures. Results reported in this study demonstrate that agriculture residues might be used as potential feedstocks for the biocellulose nanofibres production. Not only this represents a renewable source of feedstock, but also might lead to major improvements in production if proper supplements and control were utilized in the fermentation process.
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Affiliation(s)
- Yaser Dahman
- Department of Chemical Engineering, Ryerson University, Toronto, Ontario, Canada.
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130
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Liu Z, Ying Y, Li F, Ma C, Xu P. Butanol production by Clostridium beijerinckii ATCC 55025 from wheat bran. J Ind Microbiol Biotechnol 2010; 37:495-501. [PMID: 20393827 DOI: 10.1007/s10295-010-0695-8] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 02/01/2010] [Indexed: 10/19/2022]
Abstract
Wheat bran, a by-product of the wheat milling industry, consists mainly of hemicellulose, starch and protein. In this study, the hydrolysate of wheat bran pretreated with dilute sulfuric acid was used as a substrate to produce ABE (acetone, butanol and ethanol) using Clostridium beijerinckii ATCC 55025. The wheat bran hydrolysate contained 53.1 g/l total reducing sugars, including 21.3 g/l of glucose, 17.4 g/l of xylose and 10.6 g/l of arabinose. C. beijerinckii ATCC 55025 can utilize hexose and pentose simultaneously in the hydrolysate to produce ABE. After 72 h of fermentation, the total ABE in the system was 11.8 g/l, of which acetone, butanol and ethanol were 2.2, 8.8 and 0.8 g/l, respectively. The fermentation resulted in an ABE yield of 0.32 and productivity of 0.16 g l(-1) h(-1). This study suggests that wheat bran can be a potential renewable resource for ABE fermentation.
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Affiliation(s)
- Ziyong Liu
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, People's Republic of China
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131
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Noureddini H, Byun J. Dilute-acid pretreatment of distillers' grains and corn fiber. BIORESOURCE TECHNOLOGY 2010; 101:1060-7. [PMID: 19773157 DOI: 10.1016/j.biortech.2009.08.094] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 08/24/2009] [Accepted: 08/24/2009] [Indexed: 05/14/2023]
Abstract
Distillers' grains and corn fiber are the coproducts of the dry grind and wet corn milling industries, respectively. Availability of distillers' grains and corn fiber at the ethanol plant and their high levels of lignocellulosic material make them attractive feedstock for conversion to ethanol. In this study, dilute sulfuric acid hydrolysis for the conversion of distillers' grains and corn fiber to monomeric sugars and the formation of furfural were investigated. The extent of solubilization of biomass beyond monomeric sugars was also monitored. Biomass loadings in the range of 5-20 wt.% at 5% intervals, acid concentrations in the range of 0.5-1.5 vol.% at 0.5% intervals, and temperatures of 120 and 140 degrees C were studied. The highest yields of monomeric sugars were observed when the least amount of biomass loading was pretreated with the highest concentration of sulfuric acid and when the temperature was 140 degrees C. For the majority of the cases under consideration, the most effective period of hydrolysis appeared to be during the initial 20-30 min of the reaction. Formation of furfural during the course of hydrolysis was significantly lower at 120 degrees C and also lower for the distillers' grains samples compared with the corn fiber samples. The total amount of the solubilized matter during the hydrolysis was significantly higher than the amount of the monomeric sugars. Analyses according to standard procedure were performed to quantify moisture, oil, carbohydrates, and ash in distillers' grains and corn fiber samples. The total carbohydrate content of distillers' grains and corn fiber were 57.7+/-2.0 and 77.0+/-1.0 wt.%, respectively. The presented results will provide a foundation for the suitability of the pretreated distillers' grains and corn fiber for enzymatic hydrolysis step.
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Affiliation(s)
- H Noureddini
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0643, United States.
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132
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133
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Xie G, West T. Citric acid production byAspergillus nigerATCC 9142 from a treated ethanol fermentation co-product using solid-state fermentation. Lett Appl Microbiol 2009; 48:639-44. [DOI: 10.1111/j.1472-765x.2009.02586.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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134
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Cho DH, Lee YJ, Um Y, Sang BI, Kim YH. Detoxification of model phenolic compounds in lignocellulosic hydrolysates with peroxidase for butanol production from Clostridium beijerinckii. Appl Microbiol Biotechnol 2009; 83:1035-43. [PMID: 19300996 DOI: 10.1007/s00253-009-1925-8] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Revised: 02/20/2009] [Accepted: 02/20/2009] [Indexed: 11/27/2022]
Abstract
In the present study, we investigated the peroxidase-catalyzed detoxification of model phenolic compounds and evaluated the inhibitory effects of the detoxified solution on butanol production by Clostridium beijerinckii National Collection of Industrial and Marine Bacteria Ltd. 8052. The six phenolic compounds, p-coumaric acid, ferulic acid, 4-hydroxybenzoic acid, vanillic acid, syringaldehyde, and vanillin, were selected as model fermentation inhibitors generated during pretreatment and hydrolysis of lignocellulose. The enzyme reaction was optimized as a function of the reaction conditions of pH, peroxidase concentration, and hydrogen peroxide to substrate ratio. Most of the tested phenolics have a broad optimum pH range of 6.0 to 9. Removal efficiency increased with the molar ratio of H(2)O(2) to each compound up to 0.5-1.25. In the case of p-coumaric acid, ferulic acid, vanillic acid, and vanillin, the removal efficiency was almost 100% with only 0.01 microM of enzyme. The tested phenolic compounds (1 g/L) inhibited cell growth by 64-74%, while completely inhibiting the production of butanol. Although syringaldehyde and vanillin were less toxic on cell growth, the level of inhibition on the butanol production was quite different. The detoxified solution remarkably improved cell growth and surprisingly increased butanol production to the level of the control. Hence, our present study, using peroxidase for the removal of model phenolic compounds, could be applied towards the detoxification of lignocellulosic hydrolysates for butanol fermentation.
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Affiliation(s)
- Dae Haeng Cho
- Department of Chemical Engineering, Kwangwoon University, Wolgye-Dong, Nowon-Gu, Seoul, Korea
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135
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Stagewise Dilute-Acid Pretreatment and Enzyme Hydrolysis of Distillers’ Grains and Corn Fiber. Appl Biochem Biotechnol 2009; 159:553-67. [DOI: 10.1007/s12010-009-8544-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2008] [Accepted: 01/20/2009] [Indexed: 10/21/2022]
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136
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Lee SY, Park JH, Jang SH, Nielsen LK, Kim J, Jung KS. Fermentative butanol production by clostridia. Biotechnol Bioeng 2008; 101:209-28. [DOI: 10.1002/bit.22003] [Citation(s) in RCA: 773] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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137
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Kim Y, Mosier N, Ladisch MR. Process simulation of modified dry grind ethanol plant with recycle of pretreated and enzymatically hydrolyzed distillers' grains. BIORESOURCE TECHNOLOGY 2008; 99:5177-92. [PMID: 17980579 DOI: 10.1016/j.biortech.2007.09.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Distillers' grains (DG), a co-product of a dry grind ethanol process, is an excellent source of supplemental proteins in livestock feed. Studies have shown that, due to its high polymeric sugar contents and ease of hydrolysis, the distillers' grains have potential as an additional source of fermentable sugars for ethanol fermentation. The benefit of processing the distillers' grains to extract fermentable sugars lies in an increased ethanol yield without significant modification in the current dry grind technology. Three different potential configurations of process alternatives in which pretreated and hydrolyzed distillers' grains are recycled for an enhanced overall ethanol yield are proposed and discussed in this paper based on the liquid hot water (LHW) pretreatment of distillers' grains. Possible limitations of each proposed process are also discussed. This paper presents a compositional analysis of distillers' grains, as well as a simulation of the modified dry grind processes with recycle of distillers' grains. Simulated material balances for the modified dry grind processes are established based on the base case assumptions. These balances are compared to the conventional dry grind process in terms of ethanol yield, compositions of its co-products, and accumulation of fermentation inhibitors. Results show that 14% higher ethanol yield is achievable by processing and hydrolyzing the distillers' grains for additional fermentable sugars, as compared to the conventional dry grind process. Accumulation of fermentation by-products and inhibitory components in the proposed process is predicted to be 2-5 times higher than in the conventional dry grind process. The impact of fermentation inhibitors is reviewed and discussed. The final eDDGS (enhanced dried distillers' grains) from the modified processes has 30-40% greater protein content per mass than DDGS, and its potential as a value-added process is also analyzed. While the case studies used to illustrate the process simulation are based on LHW pretreated DG, the process simulation itself provides a framework for evaluation of the impact of other pretreatments.
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Affiliation(s)
- Youngmi Kim
- Laboratory of Renewable Resources Engineering, Department of Agricultural and Biological Engineering, Potter Engineering Center, 500 Central Drive, Purdue University, West Lafayette, IN 47907-2022, United States
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138
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Dien BS, Ximenes EA, O'Bryan PJ, Moniruzzaman M, Li XL, Balan V, Dale B, Cotta MA. Enzyme characterization for hydrolysis of AFEX and liquid hot-water pretreated distillers' grains and their conversion to ethanol. BIORESOURCE TECHNOLOGY 2008; 99:5216-25. [PMID: 17996446 DOI: 10.1016/j.biortech.2007.09.030] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Dried distillers' grains with solubles (DDGS), a co-product of corn ethanol production, was investigated as a feedstock for additional ethanol production. DDGS was pretreated with liquid hot-water (LHW) and ammonia fiber explosion (AFEX) processes. Cellulose was readily converted to glucose from both LHW and AFEX treated DDGS using a mixture of commercial cellulase and beta-glucosidase; however, these enzymes were ineffective at saccharifying the xylan present in the pretreated DDGS. Several commercial enzyme preparations were evaluated in combination with cellulase to saccharify pretreated DDGS xylan and it was found that adding commercial grade (e.g. impure) pectinase and feruloyl esterase (FAE) preparations were effective at releasing arabinose and xylose. The response of sugar yields for pretreated AFEX and LHW DDGS (6wt%/solids) were determined for different enzyme loadings of FAE and pectinase and modeled as a response surfaces. Arabinose and xylose yields rose with increasing FAE and pectinase enzyme dosages for both pretreated materials. When hydrolyzed at 20wt%/solids with the same blend of commercial enzymes, the yields were 278 and 261g sugars (i.e. total of arabinose, xylose, and glucose) per kg of DDGS (dry basis, db) for AFEX and LHW pretreated DDGS, respectively. The pretreated DDGS's were also evaluated for fermentation using Saccharomyces cerevisiae at 15wt%/solids. Pretreated DDGS were readily fermented and were converted to ethanol at 89-90% efficiency based upon total glucans; S. cerevisiae does not ferment arabinose or xylose.
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Affiliation(s)
- Bruce S Dien
- National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, 1815 North University Street, Peoria, IL 61604, United States.
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139
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Kim S, Dale BE. Life cycle assessment of fuel ethanol derived from corn grain via dry milling. BIORESOURCE TECHNOLOGY 2008; 99:5250-60. [PMID: 17964144 DOI: 10.1016/j.biortech.2007.09.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Life cycle analysis enables to investigate environmental performance of fuel ethanol used in an E10 fueled compact passenger vehicle. Ethanol is derived from corn grain via dry milling. This type of analysis is an important component for identifying practices that will help to ensure that a renewable fuel, such as ethanol, may be produced in a sustainable manner. Based on data from eight counties in seven Corn Belt states as corn farming sites, we show ethanol derived from corn grain as E10 fuel would reduce nonrenewable energy and greenhouse gas emissions, but would increase acidification, eutrophication and photochemical smog, compared to using gasoline as liquid fuel. The ethanol fuel systems considered in this study offer economic benefits, namely more money returned to society than the investment for producing ethanol. The environmental performance of ethanol fuel system varies significantly with corn farming sites because of different crop management practices, soil properties, and climatic conditions. The dominant factor determining most environmental impacts considered here (i.e., greenhouse gas emissions, acidification, eutrophication, and photochemical smog formation) is soil related nitrogen losses (e.g., N2O, NOx, and NO3-). The sources of soil nitrogen include nitrogen fertilizer, crop residues, and air deposition. Nitrogen fertilizer is probably the primary source. Simulations using an agro-ecosystem model predict that planting winter cover crops would reduce soil nitrogen losses and increase soil organic carbon levels, thereby greatly improving the environmental performance of the ethanol fuel system.
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Affiliation(s)
- Seungdo Kim
- Department of Chemical Engineering and Materials Science, Michigan State University, United States
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140
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Ladisch M, Dale B, Tyner W, Mosier N, Kim Y, Cotta M, Dien B, Blaschek H, Laurenas E, Shanks B, Verkade J, Schell C, Petersen G. Cellulose conversion in dry grind ethanol plants. BIORESOURCE TECHNOLOGY 2008; 99:5157-5159. [PMID: 18424042 DOI: 10.1016/j.biortech.2007.09.082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The expansion of the dry grind ethanol industry provides a unique opportunity to introduce cellulose conversion technology to existing grain to ethanol plants, while enhancing ethanol yields by up to 14%, and decreasing the volume while increasing protein content of distiller's grains. The technologies required are cellulose pretreatment, enzyme hydrolysis, fermentation, and drying. Laboratory data combined with compositional analysis and process simulations are used to present a comparative analysis of a dry grind process to a process with pretreatment and hydrolysis of cellulose in distiller's grains. The additional processing steps are projected to give a 32% increase in net present value if process modifications are made to a 100 million gallon/year plant.
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Affiliation(s)
- Michael Ladisch
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907, USA.
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