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Watanabe K, Nishijima M, Mayuzumi S, Aki T. Utilization of Sugarcane Bagasse as a Substrate for Lipid Production by Aurantiochytrium sp. J Oleo Sci 2022; 71:1493-1500. [PMID: 36089403 DOI: 10.5650/jos.ess22206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Thraustochytrid, Aurantiochytrium sp., produces various lipids such as polyunsaturated and saturated fatty acids, carotenoids, and other hydrocarbons, which are useful in the fields of health foods, cosmetics, fine chemicals, and biofuels. Lignocellulosic biomass, which is abundant and cheap, is a promising feedstock for producing cheaper bulk and high-value-added products using Aurantiochytrium sp. However, the steam explosion of lignocellulosic biomass for efficient enzymatic saccharification generates substances that inhibit the growth of microorganisms. In this study, the inhibitory activities of these by-products on the growth and lipid production of Aurantiochytrium sp. were investigated. Aurantiochytrium sp. was found to be highly sensitive to furfural and vanillin and moderately sensitive to 5-hydroxymethylfurfural and syringaldehyde. Washing steam-exploded bagasse with water, followed by activated charcoal treatment, significantly reduced furfural, which was a major inhibitory component in the saccharified solution.
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Affiliation(s)
- Kenshi Watanabe
- Graduate School of Integrated Sciences for Life, Hiroshima University
| | - Miho Nishijima
- Graduate School of Integrated Sciences for Life, Hiroshima University
| | - Shinzo Mayuzumi
- Advanced Technology Research Laboratories, Idemitsu Kosan, Co., Ltd
| | - Tsunehiro Aki
- Graduate School of Integrated Sciences for Life, Hiroshima University
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2
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Nepenthes mirabilis Fractionated Pitcher Fluid Use for Mixed Agro-Waste Pretreatment: Advocacy for Non-Chemical Use in Biorefineries. Catalysts 2022. [DOI: 10.3390/catal12070726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
This study determined whether it is feasible to pretreat mixed agro-waste of different particle sizes using the pitcher fluid of Nepenthes mirabilis (N. mirabilis), which is known to digest leaf litter due to the enzyme cocktail contained in the fluid. This is due to the need for the holocellulolysis (a source of fermentable sugars) of mixed agro-waste to produce fermentable hydrolysates. The pitcher fluid was fractionated (<3 kDa, ˃3 kDa, <10 kDa, ˃10 kDa) and slurrified with the mixed agro-waste, i.e., 25% (w/w) for each waste—orange peels, apple peels, maize cobs, grape pomace, and oak plant leaf litter of various particle sizes, i.e., >75 µm x < 106 µm and >106 µm. The process of producing a high concentration of total reducible sugars (TRSs) with the lowest production of total phenolic compounds (TPCs) was determined to be a particle size of >106 µm, pretreatment for 72 h, and an enzyme fraction of <10 kDa, whereby 97 g/L of TRSs were produced with a significantly lower TPCs load (1 g/L). Furthermore, the <10 kDa showed preferable physico-chemical properties, with the highest reduction-oxidation potential including acidity. Several enzymes, i.e., β-1,3-Glucanase, Putative peroxidase 27, Thaumatin-like protein, among others, were identified in the <10 kDa fraction, i.e., enzymes known to perform various functions in plant-based waste. Therefore, there is a need for the renewable energy industry to consider solely using pitcher fluids to pretreat mixed agro-waste for fermentable hydrolysates’ production, which can be used as liquid feedstock for the bioenergy and/or biorefinery industries for environmental pollution reduction.
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Brandt BA, García-Aparicio MDP, Görgens JF, van Zyl WH. Rational engineering of Saccharomyces cerevisiae towards improved tolerance to multiple inhibitors in lignocellulose fermentations. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:173. [PMID: 34454598 PMCID: PMC8403374 DOI: 10.1186/s13068-021-02021-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND The fermentation of lignocellulose hydrolysates to ethanol requires robust xylose-capable Saccharomyces cerevisiae strains able to operate in the presence of microbial inhibitory stresses. This study aimed at developing industrial S. cerevisiae strains with enhanced tolerance towards pretreatment-derived microbial inhibitors, by identifying novel gene combinations that confer resistance to multiple inhibitors (thus cumulative inhibitor resistance phenotype) with minimum impact on the xylose fermentation ability. The strategy consisted of multiple sequential delta-integrations of double-gene cassettes containing one gene conferring broad inhibitor tolerance (ARI1, PAD1 or TAL1) coupled with an inhibitor-specific gene (ADH6, FDH1 or ICT1). The performances of the transformants were compared with the parental strain in terms of biomass growth, ethanol yields and productivity, as well as detoxification capacities in a synthetic inhibitor cocktail, sugarcane bagasse hydrolysate as well as hardwood spent sulphite liquor. RESULTS The first and second round of delta-integrated transformants exhibited a trade-off between biomass and ethanol yield. Transformants showed increased inhibitor resistance phenotypes relative to parental controls specifically in fermentations with concentrated spent sulphite liquors at 40% and 80% v/v concentrations in 2% SC media. Unexpectedly, the xylose fermentation capacity of the transformants was reduced compared to the parental control, but certain combinations of genes had a minor impact (e.g. TAL1 + FDH1). The TAL1 + ICT1 combination negatively impacted on both biomass growth and ethanol yield, which could be linked to the ICT1 protein increasing transformant susceptibility to weak acids and temperature due to cell membrane changes. CONCLUSIONS The integration of the selected genes was proven to increase tolerance to pretreatment inhibitors in synthetic or industrial hydrolysates, but they were limited to the fermentation of glucose. However, some gene combination sequences had a reduced impact on xylose conversion.
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Affiliation(s)
- Bianca A Brandt
- Department of Microbiology, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa
| | - Maria D P García-Aparicio
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa
| | - Johann F Görgens
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa
| | - Willem H van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa.
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Vanmarcke G, Demeke MM, Foulquié-Moreno MR, Thevelein JM. Identification of the major fermentation inhibitors of recombinant 2G yeasts in diverse lignocellulose hydrolysates. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:92. [PMID: 33836811 PMCID: PMC8034183 DOI: 10.1186/s13068-021-01935-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 03/20/2021] [Indexed: 05/16/2023]
Abstract
BACKGROUND Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of several of these inhibitors has been extensively studied with non-xylose-fermenting laboratory strains, in synthetic media, and usually as single inhibitors, or with inhibitor concentrations much higher than those found in lignocellulose hydrolysates. However, the relevance of individual inhibitors in inhibitor-rich lignocellulose hydrolysates has remained unclear. RESULTS The relative importance for inhibition of ethanol fermentation by two industrial second-generation yeast strains in five lignocellulose hydrolysates, from bagasse, corn cobs and spruce, has now been investigated by spiking higher concentrations of each compound in a concentration range relevant for industrial hydrolysates. The strongest inhibition was observed with industrially relevant concentrations of furfural causing partial inhibition of both D-glucose and D-xylose consumption. Addition of 3 or 6 g/L furfural strongly reduced the ethanol titer obtained with strain MD4 in all hydrolysates evaluated, in a range of 34 to 51% and of 77 to 86%, respectively. This was followed by 5-hydroxymethylfurfural, acetic acid and formic acid, for which in general, industrially relevant concentrations caused partial inhibition of D-xylose fermentation. On the other hand, spiking with levulinic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid or vanillin caused little inhibition compared to unspiked hydrolysate. The further evolved MD4 strain generally showed superior performance compared to the previously developed strain GSE16-T18. CONCLUSION The results highlight the importance of individual inhibitor evaluation in a medium containing a genuine mix of inhibitors as well as the ethanol that is produced by the fermentation. They also highlight the potential of increasing yeast inhibitor tolerance for improving industrial process economics.
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Affiliation(s)
- Gert Vanmarcke
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
| | - Mekonnen M Demeke
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
| | - Maria R Foulquié-Moreno
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Department of Biology, KU Leuven, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium.
- Center for Microbiology, VIB, Kasteelpark Arenberg 31, 3001, Leuven-Heverlee, Flanders, Belgium.
- NovelYeast bv, Open Bio-Incubator, Erasmus High School, Laarbeeklaan 121, Jette, 1090, Brussels, Belgium.
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Evaluating the Effect of Lignocellulose-Derived Microbial Inhibitors on the Growth and Lactic Acid Production by Bacillus coagulans Azu-10. FERMENTATION-BASEL 2021. [DOI: 10.3390/fermentation7010017] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Effective lactic acid (LA) production from lignocellulosic biomass materials is challenged by several limitations related to pentose sugar utilization, inhibitory compounds, and/or fermentation conditions. In this study, a newly isolated Bacillus coagulans strain Azu-10 was obtained and showed homofermentative LA production from xylose with optimal fermentation conditions at 50 °C and pH 7.0. Growth of strain Azu-10 and LA-fermentation efficiency were evaluated in the presence of various lignocellulose-derived inhibitors (furans, carboxylic acids, and phenols) at different concentrations. Furanic lignocellulosic-derived inhibitors were completely detoxified. The strain has exhibited high biomass, complete xylose consumption, and high LA production in the presence of 1.0–4.0 g/L furfural and 1.0–5.0 g/L of hydroxymethyl furfural, separately. Moreover, strain Azu-10 exhibited high LA production in the presence of 5.0–15.0 g/L acetic acid, 5.0 g/L of formic acid, and up to 7.0 g/L of levulinic acid, separately. Besides, for phenolic compounds, p-coumaric acid was most toxic at 1.0 g/L, while syringaldehyde or p-hydroxybenzaldehyde, and vanillin at 1.0 g/L did not inhibit LA fermentation. The present study provides an interesting potential candidate for the thermophilic LA fermentation from lignocellulose-derived substrates at the industrial biorefinery level.
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Gares M, Hiligsmann S, Kacem Chaouche N. Lignocellulosic biomass and industrial bioprocesses for the production of second generation bio-ethanol, does it have a future in Algeria? SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-03442-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Promoting microbial utilization of phenolic substrates from bio-oil. ACTA ACUST UNITED AC 2019; 46:1531-1545. [DOI: 10.1007/s10295-019-02208-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 06/21/2019] [Indexed: 10/26/2022]
Abstract
Abstract
The economic viability of the biorefinery concept is limited by the valorization of lignin. One possible method of lignin valorization is biological upgrading with aromatic-catabolic microbes. In conjunction, lignin monomers can be produced by fast pyrolysis and fractionation. However, biological upgrading of these lignin monomers is limited by low water solubility. Here, we address the problem of low water solubility with an emulsifier blend containing approximately 70 wt% Tween® 20 and 30 wt% Span® 80. Pseudomonas putida KT2440 grew to an optical density (OD600) of 1.0 ± 0.2 when supplied with 1.6 wt% emulsified phenolic monomer-rich product produced by fast pyrolysis of red oak using an emulsifier dose of 0.076 ± 0.002 g emulsifier blend per g of phenolic monomer-rich product. This approach partially mitigated the toxicity of the model phenolic monomer p-coumarate to the microbe, but not benzoate or vanillin. This study provides a proof of concept that processing of biomass-derived phenolics to increase aqueous availability can enhance microbial utilization.
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Kowalczyk JE, Peng M, Pawlowski M, Lipzen A, Ng V, Singan V, Wang M, Grigoriev IV, Mäkelä MR. The White-Rot Basidiomycete Dichomitus squalens Shows Highly Specific Transcriptional Response to Lignocellulose-Related Aromatic Compounds. Front Bioeng Biotechnol 2019; 7:229. [PMID: 31616664 PMCID: PMC6763618 DOI: 10.3389/fbioe.2019.00229] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/05/2019] [Indexed: 11/13/2022] Open
Abstract
Lignocellulosic plant biomass is an important feedstock for bio-based economy. In particular, it is an abundant renewable source of aromatic compounds, which are present as part of lignin, as side-groups of xylan and pectin, and in other forms, such as tannins. As filamentous fungi are the main organisms that modify and degrade lignocellulose, they have developed a versatile metabolism to convert the aromatic compounds that are toxic at relatively low concentrations to less toxic ones. During this process, fungi form metabolites some of which represent high-value platform chemicals or important chemical building blocks, such as benzoic, vanillic, and protocatechuic acid. Especially basidiomycete white-rot fungi with unique ability to degrade the recalcitrant lignin polymer are expected to perform highly efficient enzymatic conversions of aromatic compounds, thus having huge potential for biotechnological exploitation. However, the aromatic metabolism of basidiomycete fungi is poorly studied and knowledge on them is based on the combined results of studies in variety of species, leaving the overall picture in each organism unclear. Dichomitus squalens is an efficiently wood-degrading white-rot basidiomycete that produces a diverse set of extracellular enzymes targeted for lignocellulose degradation, including oxidative enzymes that act on lignin. Our recent study showed that several intra- and extracellular aromatic compounds were produced when D. squalens was cultivated on spruce wood, indicating also versatile aromatic metabolic abilities for this species. In order to provide the first molecular level systematic insight into the conversion of plant biomass derived aromatic compounds by basidiomycete fungi, we analyzed the transcriptomes of D. squalens when grown with 10 different lignocellulose-related aromatic monomers. Significant differences for example with respect to the expression of lignocellulose degradation related genes, but also putative genes encoding transporters and catabolic pathway genes were observed between the cultivations supplemented with the different aromatic compounds. The results demonstrate that the transcriptional response of D. squalens is highly dependent on the specific aromatic compounds present suggesting that instead of a common regulatory system, fine-tuned regulation is needed for aromatic metabolism.
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Affiliation(s)
| | - Mao Peng
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University, Utrecht, Netherlands
| | - Megan Pawlowski
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Anna Lipzen
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Vivian Ng
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Vasanth Singan
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Mei Wang
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Igor V Grigoriev
- U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA, United States
| | - Miia R Mäkelä
- Department of Microbiology, University of Helsinki, Helsinki, Finland
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Okonkwo CC, Ujor V, Ezeji TC. Chromosomal integration of aldo-keto-reductase and short-chain dehydrogenase/reductase genes in Clostridium beijerinckii NCIMB 8052 enhanced tolerance to lignocellulose-derived microbial inhibitory compounds. Sci Rep 2019; 9:7634. [PMID: 31114009 PMCID: PMC6529405 DOI: 10.1038/s41598-019-44061-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/08/2019] [Indexed: 12/23/2022] Open
Abstract
In situ detoxification of lignocellulose-derived microbial inhibitory compounds is an economical strategy for the fermentation of lignocellulose-derived sugars to fuels and chemicals. In this study, we investigated homologous integration and constitutive expression of Cbei_3974 and Cbei_3904, which encode aldo-keto reductase and previously annotated short chain dehydrogenase/reductase, respectively, in Clostridium beijerinckii NCIMB 8052 (Cb), resulting in two strains: Cb_3974 and Cb_3904. Expression of Cbei_3974 led to 2-fold increase in furfural detoxification relative to Cb_3904 and Cb_wild type. Correspondingly, butanol production was up to 1.2-fold greater in furfural-challenged cultures of Cb_3974 relative to Cb_3904 and Cb_wild type. With 4-hydroxybezaldehyde and syringaldehyde supplementation, Cb_3974 showed up to 2.4-fold increase in butanol concentration when compared to Cb_3904 and Cb_wild type. Syringic and vanillic acids were considerably less deleterious to all three strains of Cb tested. Overall, Cb_3974 showed greater tolerance to furfural, 4-hydroxybezaldehyde, and syringaldehyde with improved capacity for butanol production. Hence, development of Cb_3974 represents a significant progress towards engineering solventogenic Clostridium species that are tolerant to lignocellulosic biomass hydrolysates as substrates for ABE fermentation.
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Affiliation(s)
- Christopher Chukwudi Okonkwo
- Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH, 44691, USA
| | - Victor Ujor
- Bioenergy and Biological Waste Management Program, Agricultural Technical Institute, The Ohio State University, 1328 Dover Road, Wooster, OH, 44691, USA
| | - Thaddeus Chukwuemeka Ezeji
- Department of Animal Sciences, The Ohio State University, and Ohio State Agricultural Research and Development Center (OARDC), 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH, 44691, USA.
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10
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Use of an (Hemi) Cellulolytic Enzymatic Extract Produced by Aspergilli Species Consortium in the Saccharification of Biomass Sorghum. Appl Biochem Biotechnol 2019; 189:37-48. [DOI: 10.1007/s12010-019-02991-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/01/2019] [Indexed: 10/27/2022]
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11
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Gu H, Zhu Y, Peng Y, Liang X, Liu X, Shao L, Xu Y, Xu Z, Liu R, Li J. Physiological mechanism of improved tolerance of Saccharomyces cerevisiae to lignin-derived phenolic acids in lignocellulosic ethanol fermentation by short-term adaptation. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:268. [PMID: 31755875 PMCID: PMC6854637 DOI: 10.1186/s13068-019-1610-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/04/2019] [Indexed: 05/08/2023]
Abstract
BACKGROUND Phenolic acids are lignin-derived fermentation inhibitors formed during many pretreatment processes of lignocellulosic biomass. In this study, vanillic, p-hydroxybenzoic, and syringic acids were selected as the model compounds of phenolic acids, and the effect of short-term adaptation strategies on the tolerance of S. cerevisiae to phenolic acids was investigated. The mechanism of phenolic acids tolerance in the adapted yeast strains was studied at the morphological and physiological levels. RESULTS The multiple phenolic acids exerted the synergistic inhibitory effect on the yeast cell growth. In particular, a significant interaction between vanillic and hydroxybenzoic acids was found. The optimal short-term adaptation strategies could efficiently improve the growth and fermentation performance of the yeast strain not only in the synthetic media with phenolic acids, but also in the simultaneous saccharification and ethanol fermentation of corncob residue. Morphological analysis showed that phenolic acids caused the parental strain to generate many cytoplasmic membrane invaginations with crack at the top of these sites and some mitochondria gathered around. The adapted strain presented the thicker cell wall and membrane and smaller cell size than those of the parental strain. In particular, the cytoplasmic membrane generated many little protrusions with regular shape. The cytoplasmic membrane integrity was analyzed by testing the relative electrical conductivity, leakage of intracellular substance, and permeation of fluorescent probe. The results indicated that the short-term adaptation improved the membrane integrity of yeast cell. CONCLUSION The inhibition mechanism of phenolic acid might be attributed to the combined effect of the cytoplasmic membrane damage and the intracellular acidification. The short-term adaptation strategy with varied stressors levels and adaptive processes accelerated the stress response of yeast cell structure to tolerate phenolic acids. This strategy will contribute to the development of robust microbials for biofuel production from lignocellulosic biomass.
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Affiliation(s)
- Hanqi Gu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
| | - Yuyong Zhu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Yanfang Peng
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Xiujun Liang
- Basic Medical Institute, Chengde Medical University, Chengde, 067000 Hebei China
| | - Xiaoguang Liu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Lingzhi Shao
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Yanyan Xu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Zhaohe Xu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Ran Liu
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
| | - Jie Li
- Department of Biology and Food Science, Hebei Normal University for Nationalities, Chengde, 067000 Hebei China
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Kurambhatti CV, Kumar D, Rausch KD, Tumbleson ME, Singh V. Increasing ethanol yield through fiber conversion in corn dry grind process. BIORESOURCE TECHNOLOGY 2018; 270:742-745. [PMID: 30279100 DOI: 10.1016/j.biortech.2018.09.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/10/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
Conversion of corn fiber to ethanol in the dry grind process could increase ethanol yields, reduce downstream processing costs and improve overall process profitability. This work investigates the in-situ conversion of corn fiber into ethanol (cellulase addition during simultaneous saccharification and fermentation) during dry grind process. Addition of 30 FPU/g fiber cellulase resulted in 4.6% increase in ethanol yield compared to the conventional process. Use of excess cellulase (120 FPU/g fiber) resulted in incomplete fermentation and lower ethanol yield compared to the conventional process. Multiple factors including high concentrations of ethanol and phenolic compounds were responsible for yeast stress and incomplete fermentation in excess cellulase experiments.
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Affiliation(s)
- Chinmay V Kurambhatti
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Deepak Kumar
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Kent D Rausch
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - M E Tumbleson
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - Vijay Singh
- Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States.
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13
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Cunha JT, Romaní A, Costa CE, Sá-Correia I, Domingues L. Molecular and physiological basis of Saccharomyces cerevisiae tolerance to adverse lignocellulose-based process conditions. Appl Microbiol Biotechnol 2018; 103:159-175. [PMID: 30397768 DOI: 10.1007/s00253-018-9478-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 11/27/2022]
Abstract
Lignocellulose-based biorefineries have been gaining increasing attention to substitute current petroleum-based refineries. Biomass processing requires a pretreatment step to break lignocellulosic biomass recalcitrant structure, which results in the release of a broad range of microbial inhibitors, mainly weak acids, furans, and phenolic compounds. Saccharomyces cerevisiae is the most commonly used organism for ethanol production; however, it can be severely distressed by these lignocellulose-derived inhibitors, in addition to other challenging conditions, such as pentose sugar utilization and the high temperatures required for an efficient simultaneous saccharification and fermentation step. Therefore, a better understanding of the yeast response and adaptation towards the presence of these multiple stresses is of crucial importance to design strategies to improve yeast robustness and bioconversion capacity from lignocellulosic biomass. This review includes an overview of the main inhibitors derived from diverse raw material resultants from different biomass pretreatments, and describes the main mechanisms of yeast response to their presence, as well as to the presence of stresses imposed by xylose utilization and high-temperature conditions, with a special emphasis on the synergistic effect of multiple inhibitors/stressors. Furthermore, successful cases of tolerance improvement of S. cerevisiae are highlighted, in particular those associated with other process-related physiologically relevant conditions. Decoding the overall yeast response mechanisms will pave the way for the integrated development of sustainable yeast cell-based biorefineries.
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Affiliation(s)
- Joana T Cunha
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Aloia Romaní
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Carlos E Costa
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal
| | - Isabel Sá-Correia
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Lucília Domingues
- Centre of Biological Engineering (CEB), University of Minho, 4710-057, Braga, Portugal.
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Rönnander J, Ljunggren J, Hedenström E, Wright SAI. Biotransformation of vanillin into vanillyl alcohol by a novel strain of Cystobasidium laryngis isolated from decaying wood. AMB Express 2018; 8:137. [PMID: 30143905 PMCID: PMC6109037 DOI: 10.1186/s13568-018-0666-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 08/17/2018] [Indexed: 11/19/2022] Open
Abstract
Vanillin is an aromatic aldehyde found as a component of lignocellulosic material, and in the cured pods of orchidaceae plants. Like other phenolic substances, vanillin has antimicrobial activity and can be extracted from lignin either by a thermo-chemical process or through microbial degradation. Vanillin, can serve as a model monomer in biodegradation studies of lignin. In the present study, a yeast isolated from decaying wood on the Faroe Islands, was identified as Cystobasidium laryngis strain FMYD002, based on internal transcribed spacer sequence analysis. It demonstrated the ability to convert vanillin to vanillyl alcohol, as detected by ultra-high performance liquid chromatography-quadrupole-time-of-flight. Structural analysis of vanillyl alcohol was carried out by using gas chromatography-mass spectrometry and 1H NMR spectroscopy, and further verified by synthesis. The reduction of vanillin to vanillyl alcohol has been documented for only a few species of fungi. However, to our knowledge, this biotransformation has not yet been reported for basidiomycetous yeast species, nor for any representative of the subphylum Pucciniomycotina. The biotransformation capability of the present strain might prove useful in the industrial utilisation of lignocellulosic residues.
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Affiliation(s)
- Jonas Rönnander
- Faculty of Engineering and Sustainable Development, University of Gävle, 80176, Gävle, Sweden.
| | - Joel Ljunggren
- Department of Chemical Engineering, Mid Sweden University, 85170, Sundsvall, Sweden
| | - Erik Hedenström
- Department of Chemical Engineering, Mid Sweden University, 85170, Sundsvall, Sweden
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Chen WH, Zeng YR. Mathematical model to appraise the inhibitory effect of phenolic compounds derived from lignin for biobutanol production. BIORESOURCE TECHNOLOGY 2018; 261:44-51. [PMID: 29653333 DOI: 10.1016/j.biortech.2018.04.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/30/2018] [Accepted: 04/02/2018] [Indexed: 06/08/2023]
Abstract
This study aimed to establish a mathematical modeling to evaluate the inhibitory effect of phenolic derivatives on acetone-butanol-ethanol (ABE) fermentation by Clostridium saccharoperbutylacetonicum N1-4. Vanillin, 4-hydroxybenzoic acid, and syringaldehyde were selected to represent guaiacyl, hydroxyphenyl, and syringyl phenols, respectively, to be examined in a series of fed-batch experiments. Results show the presence of phenolic derivatives blocked the pathway of the assimilation of organic acids and reduced cell growth and glucose utilization. The inhibition model projected that the levels of 0.13, 0.14, and 0.04 g L-1 for vanillin, 4-hydroxybenzoic acid, and syringaldehyde, respectively, resulted in 25% inhibition of butanol production, whereas 100% inhibition was predicted at the levels of 4.94, 4.37, and 4.20 g L-1 for vanillin, 4-hydroxybenzoic acid, and syringaldehyde, respectively. Syringaldehyde was more toxic than the other two compounds. The established model described that the phenolic compounds derived from different phenyl propane monomers of lignin severely obstructed biobutanol production.
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Affiliation(s)
- Wen-Hsing Chen
- Department of Environmental Engineering, National Ilan University, Yilan 260, Taiwan.
| | - Yan-Ru Zeng
- Department of Environmental Engineering, National Ilan University, Yilan 260, Taiwan
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16
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Detoxification of Organosolv-Pretreated Pine Prehydrolysates with Anion Resin and Cysteine for Butanol Fermentation. Appl Biochem Biotechnol 2018; 186:662-680. [PMID: 29717408 DOI: 10.1007/s12010-018-2769-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 04/23/2018] [Indexed: 10/17/2022]
Abstract
Bioconversion of lignocellulose to biofuels suffers from the degradation compounds formed during pretreatment and acid hydrolysis. In order to achieve an efficient biomass to biofuel conversion, detoxification is often required before enzymatic hydrolysis and microbial fermentation. Prehydrolysates from ethanol organosolv-pretreated pine wood were used as substrates in butanol fermentation in this study. Six detoxification approaches were studied and compared, including overliming, anion exchange resin, nonionic resin, laccase, activated carbon, and cysteine. It was observed that detoxification by anion exchange resin was the most effective method. The final butanol yield after anion exchange resin treatment was comparable to the control group, but the fermentation was delayed for 72 h. The addition of Ca(OH)2 was found to alleviate this delay and improve the fermentation efficiency. The combination of Ca(OH)2 and anion exchange resin resulted in completion of fermentation within 72 h and acetone-butanol-ethanol (ABE) production of 11.11 g/L, corresponding to a yield of 0.21 g/g sugar. The cysteine detoxification also resulted in good detoxification performance, but promoted fermentation towards acid production (8.90 g/L). The effect of salt on ABE fermentation was assessed and the possible role of Ca(OH)2 was to remove the salts in the prehydrolysates by precipitation.
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17
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Lyra Colombi B, Silva Zanoni PR, Benathar Ballod Tavares L. Effect of phenolic compounds on bioconversion of glucose to ethanol by yeast Saccharomyces cerevisiae
PE-2. CAN J CHEM ENG 2018. [DOI: 10.1002/cjce.23114] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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18
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Wordofa GG, Kristensen M. Tolerance and metabolic response of Pseudomonas taiwanensis VLB120 towards biomass hydrolysate-derived inhibitors. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:199. [PMID: 30034525 PMCID: PMC6052574 DOI: 10.1186/s13068-018-1192-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 07/06/2018] [Indexed: 05/10/2023]
Abstract
BACKGROUND Bio-conversion of lignocellulosic biomass to high-value products offers numerous benefits; however, its development is hampered by chemical inhibitors generated during the pretreatment process. A better understanding of how microbes naturally respond to those inhibitors is valuable in the process of designing microorganisms with improved tolerance. Pseudomonas taiwanensis VLB120 is a natively tolerant strain that utilizes a wide range of carbon sources including pentose and hexose sugars. To this end, we investigated the tolerance and metabolic response of P. taiwanensis VLB120 towards biomass hydrolysate-derived inhibitors including organic acids (acetic acid, formic acid, and levulinic acid), furans (furfural, 5-hydroxymethylfurfural), and phenols (vanillin). RESULTS The inhibitory effect of the tested compounds varied with respect to lag phase, specific growth rate, and biomass yield compared to the control cultures grown under the same conditions without addition of inhibitors. However, P. taiwanensis was able to oxidize vanillin and furfural to vanillic acid and 2-furoic acid, respectively. Vanillic acid was further metabolized, whereas 2-furoic acid was secreted outside the cells and remained in the fermentation broth without further conversion. Acetic acid and formic acid were completely consumed from the fermentation broth, while concentration of levulinic acid remained constant throughout the fermentation process. Analysis of free intracellular metabolites revealed varying levels when P. taiwanensis VLB120 was exposed to inhibitory compounds. This resulted in increased levels of ATP to export inhibitors from the cell and NADPH/NADP ratio that provides reducing power to deal with the oxidative stress caused by the inhibitors. Thus, adequate supply of these metabolites is essential for the survival and reproduction of P. taiwanensis in the presence of biomass-derived inhibitors. CONCLUSIONS In this study, the tolerance and metabolic response of P. taiwanensis VLB120 to biomass hydrolysate-derived inhibitors was investigated. P. taiwanensis VLB120 showed high tolerance towards biomass hydrolysate-derived inhibitors compared to most wild-type microbes reported in the literature. It adopts different resistance mechanisms, including detoxification, efflux, and repair, which require additional energy and resources. Thus, targeting redox and energy metabolism in strain engineering may be a successful strategy to overcome inhibition during biomass hydrolysate conversion and lead to development of more robust strains.
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Affiliation(s)
- Gossa G. Wordofa
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Mette Kristensen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800 Lyngby, Denmark
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Wang Y, Shao Y, Zou X, Yang M, Guo L. Synergistic action between extracellular products from white-rot fungus and cellulase significantly improves enzymatic hydrolysis. Bioengineered 2018; 9:178-185. [PMID: 28384075 PMCID: PMC5972936 DOI: 10.1080/21655979.2017.1308991] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
With a set of perfect extracellular lignocellulolytic enzymes, white-rot fungus has been recognized as playing an important role in the degradation of lignocellulose materials, which leads to the possibility of creating a composite enzymatic system with high hydrolysis efficiency in vitro. Echinodontium taxodii is a promising white-rot fungus for biologic pretreatment. In this study, we extracted the extracellular products of E. taxodii under solid-state fermentation conditions, mixed the extracellular products with cellulase to build a composite enzymatic system, and systematically evaluated the effect of this system on the hydrolysis of acid-pretreated and raw maize stovers. We found that the extracellular products from E. taxodii could significantly improve the hydrolysis efficiency of cellulase, with a synergistic action between the extracellular products and cellulase. Corn stovers treated with extracellular products were suitable for the enzymatic hydrolysis of cellulase. Furthermore, we found that pure proteins from the extracellular products were not sufficient to generate synergistic action. This finding suggests that non-protein substances may also be involved in the synergistic action between the extracellular products and cellulase.
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Affiliation(s)
- Yushan Wang
- a Department of Biotechnology , Heilongjiang Vocational Institute of Ecological Engineering, Heilongjiang Province , China
| | - Yang Shao
- a Department of Biotechnology , Heilongjiang Vocational Institute of Ecological Engineering, Heilongjiang Province , China
| | - Xinyue Zou
- a Department of Biotechnology , Heilongjiang Vocational Institute of Ecological Engineering, Heilongjiang Province , China
| | - Mandi Yang
- a Department of Biotechnology , Heilongjiang Vocational Institute of Ecological Engineering, Heilongjiang Province , China
| | - Lin Guo
- a Department of Biotechnology , Heilongjiang Vocational Institute of Ecological Engineering, Heilongjiang Province , China
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Todhanakasem T, Yodsanga S, Sowatad A, Kanokratana P, Thanonkeo P, Champreda V. Inhibition analysis of inhibitors derived from lignocellulose pretreatment on the metabolic activity of Zymomonas mobilis
biofilm and planktonic cells and the proteomic responses. Biotechnol Bioeng 2017; 115:70-81. [DOI: 10.1002/bit.26449] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/29/2017] [Accepted: 09/04/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Tatsaporn Todhanakasem
- Department of Agro-Industry; Faculty of Biotechnology; Assumption University; Bangkok Thailand
| | - Supanika Yodsanga
- Department of Agro-Industry; Faculty of Biotechnology; Assumption University; Bangkok Thailand
| | - Apinya Sowatad
- Department of Agro-Industry; Faculty of Biotechnology; Assumption University; Bangkok Thailand
| | - Pattanop Kanokratana
- National Center for Genetic Engineering and Biotechnology (BIOTEC); Pathumthani Thailand
| | | | - Verawat Champreda
- National Center for Genetic Engineering and Biotechnology (BIOTEC); Pathumthani Thailand
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Lv X, Xiong C, Li S, Chen X, Xiao W, Zhang D, Li J, Gong Y, Lin J, Liu Z. Vacuum-assisted alkaline pretreatment as an innovative approach for enhancing fermentable sugar yield and decreasing inhibitor production of sugarcane bagasse. BIORESOURCE TECHNOLOGY 2017; 239:402-411. [PMID: 28538197 DOI: 10.1016/j.biortech.2017.04.053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/12/2017] [Accepted: 04/13/2017] [Indexed: 06/07/2023]
Abstract
Sodium hydroxide pretreatment of sugarcane bagasse under vacuum conditions was established and evaluated in this study. Compared to pretreatment under conventional moderate pressure conditions, only half of the total phenolic compounds and less than half of the formic acid were produced under vacuum conditions, while the yield of total fermentable sugar was significantly increased by 31.38%. The pretreatment parameters: NaOH concentration, pretreatment time, and pretreatment temperature, were optimized using response surface methodology based on the response values of the total fermentable sugar yield (TFSY) and the total fermentable sugar concentration (TFSC), respectively. Under the optimal conditions, the TFSY of 0.5146g/g and the TFSC of 17.37g/L were achieved, respectively. By adjusting the ratio of cellulases to xylanase, the TFSY reached a maximum of 0.5213g/g when the ratio was 1:1, while the maximum TFSC of 17.71g/L was achieved when the ratio was 1:4.
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Affiliation(s)
- Xiaojing Lv
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Chunjiang Xiong
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China; Research and Development Department, Guangdong Qizhi Biotechnology Co., Ltd., Guangzhou, PR China
| | - Shuai Li
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Xiaodong Chen
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Wenjuan Xiao
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Dou Zhang
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Jiasheng Li
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Yingxue Gong
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Jianghai Lin
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China
| | - Zehuan Liu
- Research Center for Molecular Biology, Institutes of Life and Health Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632, PR China.
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22
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Luque L, Oudenhoven S, Westerhof R, van Rossum G, Berruti F, Kersten S, Rehmann L. Comparison of ethanol production from corn cobs and switchgrass following a pyrolysis-based biorefinery approach. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:242. [PMID: 28702087 PMCID: PMC5505144 DOI: 10.1186/s13068-016-0661-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 11/01/2016] [Indexed: 06/07/2023]
Abstract
BACKGROUND One of the main obstacles in lignocellulosic ethanol production is the necessity of pretreatment and fractionation of the biomass feedstocks to produce sufficiently pure fermentable carbohydrates. In addition, the by-products (hemicellulose and lignin fraction) are of low value, when compared to dried distillers grains (DDG), the main by-product of corn ethanol. Fast pyrolysis is an alternative thermal conversion technology for processing biomass. It has recently been optimized to produce a stream rich in levoglucosan, a fermentable glucose precursor for biofuel production. Additional product streams might be of value to the petrochemical industry. However, biomass heterogeneity is known to impact the composition of pyrolytic product streams, as a complex mixture of aromatic compounds is recovered with the sugars, interfering with subsequent fermentation. The present study investigates the feasibility of fast pyrolysis to produce fermentable pyrolytic glucose from two abundant lignocellulosic biomass sources in Ontario, switchgrass (potential energy crop) and corn cobs (by-product of corn industry). RESULTS Demineralization of biomass removes catalytic centers and increases the levoglucosan yield during pyrolysis. The ash content of biomass was significantly decreased by 82-90% in corn cobs when demineralized with acetic or nitric acid, respectively. In switchgrass, a reduction of only 50% for both acids could be achieved. Conversely, levoglucosan production increased 9- and 14-fold in corn cobs when rinsed with acetic and nitric acid, respectively, and increased 11-fold in switchgrass regardless of the acid used. After pyrolysis, different configurations for upgrading the pyrolytic sugars were assessed and the presence of potentially inhibitory compounds was approximated at each step as double integral of the UV spectrum signal of an HPLC assay. The results showed that water extraction followed by acid hydrolysis and solvent extraction was the best upgrading strategy. Ethanol yields achieved based on initial cellulose fraction were 27.8% in switchgrass and 27.0% in corn cobs. CONCLUSIONS This study demonstrates that ethanol production from switchgrass and corn cobs is possible following a combined thermochemical and fermentative biorefinery approach, with ethanol yields comparable to results in conventional pretreatments and fermentation processes. The feedstock-independent fermentation ability can easily be assessed with a simple assay.
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Affiliation(s)
- Luis Luque
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street, London, ON Canada
- Institute for Chemicals and Fuels from Alternative Resources, University of Western Ontario, 22312 Wonderland Road, Ilderton, ON Canada
| | - Stijn Oudenhoven
- Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Roel Westerhof
- Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Guus van Rossum
- Shell Global Solutions International BV, P.O. Box 38000, 1030 BN Amsterdam, The Netherlands
| | - Franco Berruti
- Institute for Chemicals and Fuels from Alternative Resources, University of Western Ontario, 22312 Wonderland Road, Ilderton, ON Canada
| | - Sascha Kersten
- Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Lars Rehmann
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street, London, ON Canada
- Institute for Chemicals and Fuels from Alternative Resources, University of Western Ontario, 22312 Wonderland Road, Ilderton, ON Canada
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Rosales-Calderon O, Trajano HL, Posarac D, Duff SJ. Modeling of Oxygen Delignified Wheat Straw Enzymatic Hydrolysis as a Function of Hydrolysis Time, Enzyme Concentration, and Lignin Content. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1089/ind.2015.0037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Oscar Rosales-Calderon
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Heather L. Trajano
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Dusko Posarac
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Sheldon J.B. Duff
- Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada
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24
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van der Pol EC, Vaessen E, Weusthuis RA, Eggink G. Identifying inhibitory effects of lignocellulosic by-products on growth of lactic acid producing micro-organisms using a rapid small-scale screening method. BIORESOURCE TECHNOLOGY 2016; 209:297-304. [PMID: 26990397 DOI: 10.1016/j.biortech.2016.03.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 03/04/2016] [Accepted: 03/05/2016] [Indexed: 05/14/2023]
Abstract
Sugars obtained from pretreated lignocellulose are interesting as substrate for the production of lactic acid in fermentation processes. However, by-products formed during pretreatment of lignocellulose can inhibit microbial growth. In this study, a small-scale rapid screening method was used to identify inhibitory effects of single and combined by-products on growth of lactic acid producing micro-organisms. The small-scale screening was performed in 48-well plates using 5 bacterial species and 12 by-products. Large differences were observed in inhibitory effects of by-products between different species. Predictions can be made for growth behaviour of different micro-organisms on acid pretreated or alkaline pretreated bagasse substrates using data from the small-scale screening. Both individual and combined inhibition effects were shown to be important parameters to predict growth. Synergy between coumaric acid, formic acid and acetic acid is a key inhibitory parameter in alkaline pretreated lignocellulose, while furfural is a key inhibitor in acid pretreated lignocellulose.
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Affiliation(s)
- Edwin C van der Pol
- Food and Biobased Research, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, Netherlands; Bioprocess Engineering, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, Netherlands.
| | - Evelien Vaessen
- Bioprocess Engineering, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, Netherlands
| | - Ruud A Weusthuis
- Bioprocess Engineering, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, Netherlands
| | - Gerrit Eggink
- Food and Biobased Research, Wageningen University and Research Centre, PO Box 17, 6700 AA Wageningen, Netherlands; Bioprocess Engineering, Wageningen University and Research Centre, PO Box 16, 6700 AA Wageningen, Netherlands
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Jiang T, Qiao H, Zheng Z, Chu Q, Li X, Yong Q, Ouyang J. Lactic Acid Production from Pretreated Hydrolysates of Corn Stover by a Newly Developed Bacillus coagulans Strain. PLoS One 2016; 11:e0149101. [PMID: 26863012 PMCID: PMC4749344 DOI: 10.1371/journal.pone.0149101] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 01/27/2016] [Indexed: 01/20/2023] Open
Abstract
An inhibitor-tolerance strain, Bacillus coagulans GKN316, was developed through atmospheric and room temperature plasma (ARTP) mutation and evolution experiment in condensed dilute-acid hydrolysate (CDH) of corn stover. The fermentabilities of other hydrolysates with B. coagulans GKN316 and the parental strain B. coagulans NL01 were assessed. When using condensed acid-catalyzed steam-exploded hydrolysate (CASEH), condensed acid-catalyzed liquid hot water hydrolysate (CALH) and condensed acid-catalyzed sulfite hydrolysate (CASH) as substrates, the concentration of lactic acid reached 45.39, 16.83, and 18.71 g/L by B. coagulans GKN316, respectively. But for B. coagulans NL01, only CASEH could be directly fermented to produce 15.47 g/L lactic acid. The individual inhibitory effect of furfural, 5-hydroxymethylfurfural (HMF), vanillin, syringaldehyde and p-hydroxybenzaldehyde (pHBal) on xylose utilization by B. coagulans GKN316 was also studied. The strain B. coagulans GKN316 could effectively convert these toxic inhibitors to the less toxic corresponding alcohols in situ. These results suggested that B. coagulans GKN316 was well suited to production of lactic acid from undetoxified lignocellulosic hydrolysates.
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Affiliation(s)
- Ting Jiang
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Hui Qiao
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Zhaojuan Zheng
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Qiulu Chu
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Xin Li
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Qiang Yong
- Key Laboratory of Forest Genetics and Biotechnology of the Ministry of Education, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
| | - Jia Ouyang
- College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
- Key Laboratory of Forest Genetics and Biotechnology of the Ministry of Education, Nanjing Forestry University, Nanjing, 210037, People’s Republic of China
- * E-mail:
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26
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Thompson OA, Hawkins GM, Gorsich SW, Doran-Peterson J. Phenotypic characterization and comparative transcriptomics of evolved Saccharomyces cerevisiae strains with improved tolerance to lignocellulosic derived inhibitors. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:200. [PMID: 27679668 PMCID: PMC5029107 DOI: 10.1186/s13068-016-0614-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/07/2016] [Indexed: 05/15/2023]
Abstract
BACKGROUND Lignocellulosic biomass continues to be investigated as a viable source for bioethanol production. However, the pretreatment process generates inhibitory compounds that impair the growth and fermentation performance of microorganisms such as Saccharomyces cerevisiae. Pinewood specifically has been shown to be challenging in obtaining industrially relevant ethanol titers. An industrial S. cerevisiae strain was subjected to directed evolution and adaptation in pretreated pine biomass and resultant strains, GHP1 and GHP4, exhibited improved growth and fermentative ability on pretreated pine in the presence of related inhibitory compounds. A comparative transcriptomic approach was applied to identify and characterize differences in phenotypic stability of evolved strains. RESULTS Evolved strains displayed different fermentative capabilities with pretreated pine that appear to be influenced by the addition or absence of 13 inhibitory compounds during pre-culturing. GHP4 performance was consistent independent of culturing conditions, while GHP1 performance was dependent on culturing with inhibitors. Comparative transcriptomics revealed 52 genes potentially associated with stress responses to multiple inhibitors simultaneously. Fluorescence microscopy revealed improved cellular integrity of both strains with mitochondria exhibiting resistance to the damaging effects of inhibitors in contrast to the parent. CONCLUSIONS Multiple potentially novel genetic targets have been discovered for understanding stress tolerance through the characterization of our evolved strains. This study specifically examines the synergistic effects of multiple inhibitors and identified targets will guide future studies in remediating effects of inhibitors and further development of robust yeast strains for multiple industrial applications.
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Affiliation(s)
| | - Gary M. Hawkins
- Department of Microbiology, University of Georgia, Athens, GA 30602 USA
| | - Steven W. Gorsich
- Department of Biology, Central Michigan University, Mount Pleasant, MI 48859 USA
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27
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Hou X, Hansen JH, Bjerre AB. Integrated bioethanol and protein production from brown seaweed Laminaria digitata. BIORESOURCE TECHNOLOGY 2015; 197:310-7. [PMID: 26342344 DOI: 10.1016/j.biortech.2015.08.091] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/24/2015] [Accepted: 08/25/2015] [Indexed: 05/07/2023]
Abstract
A wild-growing glucose-rich (i.e. 56.7% glucose content) brown seaweed species Laminaria digitata, collected from the North Coast of Denmark in August 2012, was used as the feedstock for an integrated bioethanol and protein production. Glutamic acid and aspartic acid are the two most abundant amino acids in the algal protein, both with proportional content of 10% in crude protein. Only minor pretreatment of milling was used on the biomass to facilitate the subsequent enzymatic hydrolysis and fermentation. The Separate Hydrolysis and Fermentation (SHF) resulted in obviously higher ethanol yield than the Simultaneous Saccharification and Fermentation (SSF). High conversion rate at maximum of 84.1% glucose recovery by enzymatic hydrolysis and overall ethanol yield at maximum of 77.7% theoretical were achieved. Protein content in the solid residues after fermentation was enriched by 2.7 fold, with similar distributions of amino acids, due to the hydrolysis of polymers in the seaweed cell wall matrix.
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Affiliation(s)
- Xiaoru Hou
- Danish Technological Institute, Gregersensvej 1, DK 2630, Denmark.
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Effects of lignocellulose-derived inhibitors on growth and succinic acid accumulation by Corynebacterium glutamicum. BIOTECHNOL BIOPROC E 2015. [DOI: 10.1007/s12257-015-0201-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Muddassar HR, Sipponen MH, Melin K, de Kokkonen D, Pastinen O, Golam S. Effects of Catalysts and pH on Lignin in Partial Wet Oxidation of Wood and Straw Black Liquors. Ind Eng Chem Res 2015. [DOI: 10.1021/acs.iecr.5b01764] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hassan R. Muddassar
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
| | - Mika H. Sipponen
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
| | - Kristian Melin
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
| | - Daniela de Kokkonen
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
| | - Ossi Pastinen
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
| | - Sarwar Golam
- Department of Biotechnology
and Chemical Technology, Aalto University School of Chemical Technology, 02150 Espoo, Finland
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Austin S, Kontur WS, Ulbrich A, Oshlag Z, Zhang W, Higbee A, Zhang Y, Coon JJ, Hodge DB, Donohue TJ, Noguera DR. Metabolism of Multiple Aromatic Compounds in Corn Stover Hydrolysate by Rhodopseudomonas palustris. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8914-22. [PMID: 26121369 PMCID: PMC5031247 DOI: 10.1021/acs.est.5b02062] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Lignocellulosic biomass hydrolysates hold great potential as a feedstock for microbial biofuel production, due to their high concentration of fermentable sugars. Present at lower concentrations are a suite of aromatic compounds that can inhibit fermentation by biofuel-producing microbes. We have developed a microbial-mediated strategy for removing these aromatic compounds, using the purple nonsulfur bacterium Rhodopseudomonas palustris. When grown photoheterotrophically in an anaerobic environment, R. palustris removes most of the aromatics from ammonia fiber expansion (AFEX) treated corn stover hydrolysate (ACSH), while leaving the sugars mostly intact. We show that R. palustris can metabolize a host of aromatic substrates in ACSH that have either been previously described as unable to support growth, such as methoxylated aromatics, and those that have not yet been tested, such as aromatic amides. Removing the aromatics from ACSH with R. palustris, allowed growth of a second microbe that could not grow in the untreated ACSH. By using defined mutants, we show that most of these aromatic compounds are metabolized by the benzoyl-CoA pathway. We also show that loss of enzymes in the benzoyl-CoA pathway prevents total degradation of the aromatics in the hydrolysate, and instead allows for biological transformation of this suite of aromatics into selected aromatic compounds potentially recoverable as an additional bioproduct.
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Affiliation(s)
- Samantha Austin
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Wayne S. Kontur
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Arne Ulbrich
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Zachary Oshlag
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Weiping Zhang
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Alan Higbee
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Yaoping Zhang
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Joshua J. Coon
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- Department of Biomolecular Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - David B. Hodge
- Department of Chemical Engineering & Materials Science, Michigan State University, East Lansing, Michigan 48824, United States
- Department of Biosystems & Agricultural Engineering, Michigan State University, East Lansing, Michigan 48824, United States
| | - Timothy J. Donohue
- Department of Bacteriology, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
| | - Daniel R. Noguera
- Department of Civil and Environmental Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin–Madison, Madison, Wisconsin 53706, United States
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Kurosawa K, Laser J, Sinskey AJ. Tolerance and adaptive evolution of triacylglycerol-producing Rhodococcus opacus to lignocellulose-derived inhibitors. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:76. [PMID: 26052344 PMCID: PMC4456722 DOI: 10.1186/s13068-015-0258-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/29/2015] [Indexed: 05/24/2023]
Abstract
BACKGROUND Lignocellulosic biomass has been investigated as a renewable non-food source for production of biofuels. A significant technical challenge to using lignocellulose is the presence of microbial growth inhibitors generated during pretreatment processes. Triacylglycerols (TAGs) are potential precursors for lipid-based biofuel production. Rhodococcus opacus MITXM-61 is an oleaginous bacterium capable of producing large amounts of TAGs on high concentrations of glucose and xylose present in lignocellulosic hydrolysates. However, this strain is sensitive to ligonocellulose-derived inhibitors. To understand the toxic effects of the inhibitors in lignocellulosic hydrolysates, strain MITXM-61 was examined for tolerance toward the potential inhibitors and was subjected to adaptive evolution for the resistance to the inhibitors. RESULTS We investigated growth-inhibitory effects by potential lignocellulose-derived inhibitors of phenols (lignin, vanillin, 4-hydroxybenzaldehyde (4-HB), syringaldehyde), furans (furfural and 5-hydroxymethyl-2-furaldehyde), and organic acids (levulinic acid, formic acid, and acetic acid) on the growth and TAG production of strain MITXM-61. Phenols and furans exhibited potent inhibitory effects at a concentration of 1 g L(-1), while organic acids had insignificant impacts at concentrations of up to 2 g L(-1). In an attempt to improve the inhibitor tolerance of strain MITXM-61, we evaluated the adaptation of this strain to the potential inhibitors. Adapted mutants were generated on defined agar media containing lignin, 4-HB, and syringaldehyde. Strain MITXM-61(SHL33) with improved multiple resistance of lignin, 4-HB, and syringaldehyde was constructed through adaptive evolution-based strategies. The evolved strain exhibited a two- to threefold increase in resistance to lignin, 4-HB, and syringaldehyde at 50% growth-inhibitory concentrations, compared to the parental strain. When grown in genuine lignocellulosic hydrolysates of corn stover, wheat straw, and hardwood containing growth inhibitors, strain MITXM-61(SHL33) exhibited a markedly shortened lag phase in comparison with that of strain MITXM-61. CONCLUSION This study provides important clues to overcome the negative effects of inhibitors in lignocellulosic hydrolysates on TAG production of R. opacus cells. The findings can contribute to significant progress in detoxified pretreatment of hydrolysates and development of more efficient strains for industrial TAG fermentations of R. opacus using lignocellulosic biomass.
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Affiliation(s)
- Kazuhiko Kurosawa
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Josephine Laser
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- />Present address: Institute of Biotechnology, Department Applied and Molecular Microbiology Berlin University of Technology, Gustav-Meyer-Allee 25, Berlin, D-13355 Germany
| | - Anthony J Sinskey
- />Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- />Engineering Systems Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
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Feldman D, Kowbel DJ, Glass NL, Yarden O, Hadar Y. Detoxification of 5-hydroxymethylfurfural by the Pleurotus ostreatus lignolytic enzymes aryl alcohol oxidase and dehydrogenase. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:63. [PMID: 25897324 PMCID: PMC4403834 DOI: 10.1186/s13068-015-0244-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/24/2015] [Indexed: 05/09/2023]
Abstract
BACKGROUND Current large-scale pretreatment processes for lignocellulosic biomass are generally accompanied by the formation of toxic degradation products, such as 5-hydroxymethylfurfural (HMF), which inhibit cellulolytic enzymes and fermentation by ethanol-producing yeast. Overcoming these toxic effects is a key technical barrier in the biochemical conversion of plant biomass to biofuels. Pleurotus ostreatus, a white-rot fungus, can efficiently degrade lignocellulose. In this study, we analyzed the ability of P. ostreatus to tolerate and metabolize HMF and investigated relevant molecular pathways associated with these processes. RESULTS P. ostreatus was capable to metabolize and detoxify HMF 30 mM within 48 h, converting it into 2,5-bis-hydroxymethylfuran (HMF alcohol) and 2,5-furandicarboxylic acid (FDCA), which subsequently allowed the normal yeast growth in amended media. We show that two enzymes groups, which belong to the ligninolytic system, aryl-alcohol oxidases and a dehydrogenase, are involved in this process. HMF induced the transcription and production of these enzymes and was accompanied by an increase in activity levels. We also demonstrate that following the induction of these enzymes, HMF could be metabolized in vitro. CONCLUSIONS Aryl-alcohol oxidase and dehydrogenase gene family members are part of the transcriptional and subsequent translational response to HMF exposure in P. ostreatus and are involved in HMF transformation. Based on our data, we propose that these enzymatic capacities of P. ostreatus either be integrated in biomass pretreatment or the genes encoding these enzymes may function to detoxify HMF via heterologous expression in fermentation organisms, such as Saccharomyces cerevisiae.
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Affiliation(s)
- Daria Feldman
- />Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot, 76100 Israel
| | - David J Kowbel
- />Department of Plant and Microbial Biology, University of California at Berkeley, 111 Koshland Hall, Berkeley, California 94720 USA
| | - N Louise Glass
- />Department of Plant and Microbial Biology, University of California at Berkeley, 111 Koshland Hall, Berkeley, California 94720 USA
| | - Oded Yarden
- />Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot, 76100 Israel
| | - Yitzhak Hadar
- />Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot, 76100 Israel
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van der Pol E, Bakker R, van Zeeland A, Sanchez Garcia D, Punt A, Eggink G. Analysis of by-product formation and sugar monomerization in sugarcane bagasse pretreated at pilot plant scale: differences between autohydrolysis, alkaline and acid pretreatment. BIORESOURCE TECHNOLOGY 2015; 181:114-23. [PMID: 25643957 DOI: 10.1016/j.biortech.2015.01.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 05/20/2023]
Abstract
Sugarcane bagasse is an interesting feedstock for the biobased economy since a large fraction is polymerized sugars. Autohydrolysis, alkaline and acid pretreatment conditions combined with enzyme hydrolysis were used on lignocellulose rich bagasse to acquire monomeric. By-products found after pretreatment included acetic, glycolic and coumaric acid in concentrations up to 40, 21 and 2.5 g/kg dry weight bagasse respectively. Alkaline pretreated material contained up to 45 g/kg bagasse DW of sodium. Acid and autohydrolysis pretreatment results in a furan formation of 14 g/kg and 25 g/kg DW bagasse respectively. Enzyme monomerization efficiencies of pretreated solid material after 72 h were 81% for acid pretreatment, 77% for autohydrolysis and 57% for alkaline pretreatment. Solid material was washed with superheated water to decrease the amount of by-products. Washing decreased organic acid, phenol and furan concentrations in solid material by at least 60%, without a major sugar loss.
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Affiliation(s)
- Edwin van der Pol
- Food and Biobased Research, Wageningen University and Research Center, PO Box 17, 6700 AA Wageningen, The Netherlands; Bioprocess Engineering, Wageningen University and Research Center, PO Box 16, 6700 AA Wageningen, The Netherlands.
| | - Rob Bakker
- Food and Biobased Research, Wageningen University and Research Center, PO Box 17, 6700 AA Wageningen, The Netherlands
| | - Alniek van Zeeland
- Food and Biobased Research, Wageningen University and Research Center, PO Box 17, 6700 AA Wageningen, The Netherlands
| | | | - Arjen Punt
- Laboratory of Food Chemistry, Wageningen University and Research center, Bornse Weilanden 9, 6708 WG, The Netherlands
| | - Gerrit Eggink
- Food and Biobased Research, Wageningen University and Research Center, PO Box 17, 6700 AA Wageningen, The Netherlands; Bioprocess Engineering, Wageningen University and Research Center, PO Box 16, 6700 AA Wageningen, The Netherlands
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Challenges for the production of bioethanol from biomass using recombinant yeasts. ADVANCES IN APPLIED MICROBIOLOGY 2015; 92:89-125. [PMID: 26003934 DOI: 10.1016/bs.aambs.2015.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lignocellulose biomass, one of the most abundant renewable resources on the planet, is an alternative sustainable energy source for the production of second-generation biofuels. Energy in the form of simple or complex carbohydrates can be extracted from lignocellulose biomass and fermented by microorganisms to produce bioethanol. Despite 40 years of active and cutting-edge research invested into the development of technologies to produce bioethanol from lignocellulosic biomass, the process remains commercially unviable. This review describes the achievements that have been made in generating microorganisms capable of utilizing both simple and complex sugars from lignocellulose biomass and the fermentation of these sugars into ethanol. We also provide a discussion on the current "roadblocks" standing in the way of making second-generation bioethanol a commercially viable alternative to fossil fuels.
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Zhang J, Guo RB, Qiu YL, Qiao JT, Yuan XZ, Shi XS, Wang CS. Bioaugmentation with an acetate-type fermentation bacterium Acetobacteroides hydrogenigenes improves methane production from corn straw. BIORESOURCE TECHNOLOGY 2015; 179:306-313. [PMID: 25549904 DOI: 10.1016/j.biortech.2014.12.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/06/2014] [Accepted: 12/08/2014] [Indexed: 06/04/2023]
Abstract
The effect of bioaugmentation with an acetate-type fermentation bacterium in the phylum Bacteroidetes on the anaerobic digestion of corn straw was evaluated by batch experiments. Acetobacteroides hydrogenigenes is a promising strain for bioaugmentation with relatively high growth rate, hydrogen yields and acetate tolerance, which ferments a broad spectrum of pentoses, hexoses and polyoses mainly into acetate and hydrogen. During corn straw digestion, bioaugmentation with A. hydrogenigenes led to 19-23% increase of the methane yield, with maximum of 258.1 mL/g-corn straw achieved by 10% inoculation (control, 209.3 mL/g-corn straw). Analysis of lignocellulosic composition indicated that A. hydrogenigenes could increase removal rates of cellulose and hemicelluloses in corn straw residue by 12% and 5%, respectively. Further experiment verified that the addition of A. hydrogenigenes could improve the methane yields of methyl cellulose and xylan (models for cellulose and hemicelluloses, respectively) by 16.8% and 7.0%.
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Affiliation(s)
- Jie Zhang
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Rong-Bo Guo
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China
| | - Yan-Ling Qiu
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China.
| | - Jiang-Tao Qiao
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China
| | - Xian-Zheng Yuan
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China
| | - Xiao-Shuang Shi
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China
| | - Chuan-Shui Wang
- Shandong Industrial Engineering Laboratory of Biogas Production and Utilization, Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, PR China
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Kim TY, Oh EJ, Jin YS, Oh MK. Improved resistance against oxidative stress of engineered cellobiose-fermenting Saccharomyces cerevisiae revealed by metabolite profiling. BIOTECHNOL BIOPROC E 2015. [DOI: 10.1007/s12257-014-0301-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Tang X, da Costa Sousa L, Jin M, Chundawat SPS, Chambliss CK, Lau MW, Xiao Z, Dale BE, Balan V. Designer synthetic media for studying microbial-catalyzed biofuel production. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:1. [PMID: 26339291 PMCID: PMC4311453 DOI: 10.1186/s13068-014-0179-6] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 12/04/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND The fermentation inhibition of yeast or bacteria by lignocellulose-derived degradation products, during hexose/pentose co-fermentation, is a major bottleneck for cost-effective lignocellulosic biorefineries. To engineer microbial strains for improved performance, it is critical to understand the mechanisms of inhibition that affect fermentative organisms in the presence of major components of a lignocellulosic hydrolysate. The development of a synthetic lignocellulosic hydrolysate (SH) media with a composition similar to the actual biomass hydrolysate will be an important advancement to facilitate these studies. In this work, we characterized the nutrients and plant-derived decomposition products present in AFEX™ pretreated corn stover hydrolysate (ACH). The SH was formulated based on the ACH composition and was further used to evaluate the inhibitory effects of various families of decomposition products during Saccharomyces cerevisiae 424A (LNH-ST) fermentation. RESULTS The ACH contained high levels of nitrogenous compounds, notably amides, pyrazines, and imidazoles. In contrast, a relatively low content of furans and aromatic and aliphatic acids were found in the ACH. Though most of the families of decomposition products were inhibitory to xylose fermentation, due to their abundance, the nitrogenous compounds showed the most inhibition. From these compounds, amides (products of the ammonolysis reaction) contributed the most to the reduction of the fermentation performance. However, this result is associated to a concentration effect, as the corresponding carboxylic acids (products of hydrolysis) promoted greater inhibition when present at the same molar concentration as the amides. Due to its complexity, the formulated SH did not perfectly match the fermentation profile of the actual hydrolysate, especially the growth curve. However, the SH formulation was effective for studying the inhibitory effect of various compounds on yeast fermentation. CONCLUSIONS The formulation of SHs is an important advancement for future multi-omics studies and for better understanding the mechanisms of fermentation inhibition in lignocellulosic hydrolysates. The SH formulated in this work was instrumental for defining the most important inhibitors in the ACH. Major AFEX decomposition products are less inhibitory to yeast fermentation than the products of dilute acid or steam explosion pretreatments; thus, ACH is readily fermentable by yeast without any detoxification.
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Affiliation(s)
- Xiaoyu Tang
- />Biogas Institute of Ministry of Agriculture, Section 4-13 Remin South Road, Chengdu, 610041 P. R. China
| | - Leonardo da Costa Sousa
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
| | - Mingjie Jin
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
| | - Shishir PS Chundawat
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
- />Department of Chemical & Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Room C-150A, Piscataway, NJ 08854 USA
| | | | - Ming W Lau
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
| | - Zeyi Xiao
- />School of Chemical Engineering, Sichuan University, No. 24 South Section 1, Yihuan Road, Chengdu, 610065 P. R. China
| | - Bruce E Dale
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
| | - Venkatesh Balan
- />DOE Great Lakes Bioenergy Research Center, Biomass Conversion Research Lab (BCRL), Chemical Engineering and Materials Science, Michigan State University, 3815 Technology Boulevard, Suite 1045, Lansing, 48910 USA
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van der Pol EC, Bakker RR, Baets P, Eggink G. By-products resulting from lignocellulose pretreatment and their inhibitory effect on fermentations for (bio)chemicals and fuels. Appl Microbiol Biotechnol 2014; 98:9579-93. [PMID: 25370992 DOI: 10.1007/s00253-014-6158-9] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 11/30/2022]
Abstract
Lignocellulose might become an important feedstock for the future development of the biobased economy. Although up to 75 % of the lignocellulose dry weight consists of sugar, it is present in a polymerized state and cannot be used directly in most fermentation processes for the production of chemicals and fuels. Several methods have been developed to depolymerize the sugars present in lignocellulose, making the sugars available for fermentation. In this review, we describe five different pretreatment methods and their effect on the sugar and non-sugar fraction of lignocellulose. For several pretreatment methods and different types of lignocellulosic biomass, an overview is given of by-products formed. Most unwanted by-products present after pretreatment are dehydrated sugar monomers (furans), degraded lignin polymers (phenols) and small organic acids. Qualitative and quantitative effects of these by-products on fermentation processes have been studied. We conclude this review by giving an overview of techniques and methods to decrease inhibitory effects of unwanted by-products.
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Affiliation(s)
- Edwin C van der Pol
- Food and Biobased Research, Wageningen University and Research Center, PO Box 17, 6700 AA, Wageningen, Netherlands,
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Westman JO, Mapelli V, Taherzadeh MJ, Franzén CJ. Flocculation causes inhibitor tolerance in Saccharomyces cerevisiae for second-generation bioethanol production. Appl Environ Microbiol 2014; 80:6908-18. [PMID: 25172866 PMCID: PMC4249023 DOI: 10.1128/aem.01906-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 08/25/2014] [Indexed: 11/20/2022] Open
Abstract
Yeast has long been considered the microorganism of choice for second-generation bioethanol production due to its fermentative capacity and ethanol tolerance. However, tolerance toward inhibitors derived from lignocellulosic materials is still an issue. Flocculating yeast strains often perform relatively well in inhibitory media, but inhibitor tolerance has never been clearly linked to the actual flocculation ability per se. In this study, variants of the flocculation gene FLO1 were transformed into the genome of the nonflocculating laboratory yeast strain Saccharomyces cerevisiae CEN.PK 113-7D. Three mutants with distinct differences in flocculation properties were isolated and characterized. The degree of flocculation and hydrophobicity of the cells were correlated to the length of the gene variant. The effect of different strength of flocculation on the fermentation performance of the strains was studied in defined medium with or without fermentation inhibitors, as well as in media based on dilute acid spruce hydrolysate. Strong flocculation aided against the readily convertible inhibitor furfural but not against less convertible inhibitors such as carboxylic acids. During fermentation of dilute acid spruce hydrolysate, the most strongly flocculating mutant with dense cell flocs showed significantly faster sugar consumption. The modified strain with the weakest flocculation showed a hexose consumption profile similar to the untransformed strain. These findings may explain why flocculation has evolved as a stress response and can find application in fermentation-based biorefinery processes on lignocellulosic raw materials.
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Affiliation(s)
- Johan O Westman
- School of Engineering, University of Borås, Borås, Sweden Department of Chemical and Biological Engineering, Division of Life Sciences-Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
| | - Valeria Mapelli
- Department of Chemical and Biological Engineering, Division of Life Sciences-Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
| | | | - Carl Johan Franzén
- Department of Chemical and Biological Engineering, Division of Life Sciences-Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
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Luque L, Westerhof R, Van Rossum G, Oudenhoven S, Kersten S, Berruti F, Rehmann L. Pyrolysis based bio-refinery for the production of bioethanol from demineralized ligno-cellulosic biomass. BIORESOURCE TECHNOLOGY 2014; 161:20-28. [PMID: 24681340 DOI: 10.1016/j.biortech.2014.03.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/28/2014] [Accepted: 03/04/2014] [Indexed: 06/03/2023]
Abstract
This paper evaluates a novel biorefinery approach for the conversion of lignocellulosic biomass from pinewood. A combination of thermochemical and biochemical conversion was chosen with the main product being ethanol. Fast pyrolysis of lignocellulosic biomasss with fractional condensation of the products was used as the thermochemical process to obtain a pyrolysis-oil rich in anhydro-sugars (levoglucosan) and low in inhibitors. After hydrolysis of these anhydro-sugars, glucose was obtained which was successfully fermented, after detoxification, to obtain bioethanol. Ethanol yields comparable to traditional biochemical processing were achieved (41.3% of theoretical yield based on cellulose fraction). Additional benefits of the proposed biorefinery concept comprise valuable by-products of the thermochemical conversion like bio-char, mono-phenols (production of BTX) and pyrolytic lignin as a source of aromatic rich fuel additive. The inhibitory effect of thermochemically derived fermentation substrates was quantified numerically to compare the effects of different process configurations and upgrading steps within the biorefinery approach.
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Affiliation(s)
- Luis Luque
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street London, Ontario, Canada
| | - Roel Westerhof
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street London, Ontario, Canada; Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Guus Van Rossum
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street London, Ontario, Canada; Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Stijn Oudenhoven
- Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Sascha Kersten
- Sustainable Process Technology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Franco Berruti
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street London, Ontario, Canada
| | - Lars Rehmann
- Department of Chemical and Biochemical Engineering, University of Western Ontario, 1151 Richmond Street London, Ontario, Canada.
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41
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Adeboye PT, Bettiga M, Olsson L. The chemical nature of phenolic compounds determines their toxicity and induces distinct physiological responses in Saccharomyces cerevisiae in lignocellulose hydrolysates. AMB Express 2014; 4:46. [PMID: 24949277 PMCID: PMC4052683 DOI: 10.1186/s13568-014-0046-7] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 05/04/2014] [Indexed: 01/08/2023] Open
Abstract
We investigated the severity of the inhibitory effects of 13 phenolic compounds usually found in spruce hydrolysates (4-hydroxy-3-methoxycinnamaldehyde, homovanilyl alcohol, vanillin, syringic acid, vanillic acid, gallic acid, dihydroferulic acid, p-coumaric acid, hydroquinone, ferulic acid, homovanillic acid, 4-hydroxybenzoic acid and vanillylidenacetone). The effects of the selected compounds on cell growth, biomass yield and ethanol yield were studied and the toxic concentration threshold was defined for each compound. Using Ethanol Red, the popular industrial strain of Saccharomyces cerevisiae, we found the most toxic compound to be 4-hydroxy-3-methoxycinnamaldehyde which inhibited growth at a concentration of 1.8 mM. We also observed that toxicity did not generally follow a trend based on the aldehyde, acid, ketone or alcohol classification of phenolic compounds, but rather that other structural properties such as additional functional groups attached to the compound may determine its toxicity. Three distinctive growth patterns that effectively clustered all the compounds involved in the screening into three categories. We suggest that the compounds have different cellular targets, and that. We suggest that the compounds have different cellular targets and inhibitory mechanisms in the cells, also compounds who share similar pattern on cell growth may have similar inhibitory effect and mechanisms of inhibition.
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Zhang S, Winestrand S, Guo X, Chen L, Hong F, Jönsson LJ. Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus. Microb Cell Fact 2014; 13:62. [PMID: 24884902 PMCID: PMC4126184 DOI: 10.1186/1475-2859-13-62] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 04/21/2014] [Indexed: 11/15/2022] Open
Abstract
Background Bacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced
by certain microorganisms, principally Gluconacetobacter xylinus. BC has
a great potential of application in many fields. Lignocellulosic biomass has been
investigated as a cost-effective feedstock for BC production through pretreatment
and hydrolysis. It is well known that detoxification of lignocellulosic
hydrolysates may be required to achieve efficient production of BC. Recent results
suggest that phenolic compounds contribute to the inhibition of G.
xylinus. However, very little is known about the effect on G.
xylinus of specific lignocellulose-derived inhibitors. In this study, the
inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic
acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus,
the pH of the culture medium, and the production of BC were investigated in
detail. The stability of the phenolics in the bacterial cultures was investigated
and the main bioconversion products were identified and quantified. Results Coniferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic
acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl
aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect
on the bacteria and when the vanillin concentration was raised to 2.5 mM the
volumetric yield of BC decreased to ~40% of that obtained in control medium
without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid,
showed almost no toxic effects when less than 2.5 mM. The bacterial cultures
oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin
was reduced to vanillyl alcohol with a yield of up to 80%. Conclusions This is the first investigation of the effect of specific phenolics on the
production of BC by G. xylinus, and is also the first demonstration of
the ability of G. xylinus to convert phenolic compounds. This study gives
a better understanding of how phenolic compounds and G. xylinus cultures
are affected by each other. Investigations in this area are useful for elucidating
the mechanism behind inhibition of G. xylinus in lignocellulosic
hydrolysates and for understanding how production of BC using lignocellulosic
feedstocks can be performed in an efficient way.
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Affiliation(s)
| | | | | | | | - Feng Hong
- China-Sweden Associated Research Laboratory in Industrial Biotechnology, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China.
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Greetham D, Wimalasena T, Kerruish DWM, Brindley S, Ibbett RN, Linforth RL, Tucker G, Phister TG, Smart KA. Development of a phenotypic assay for characterisation of ethanologenic yeast strain sensitivity to inhibitors released from lignocellulosic feedstocks. J Ind Microbiol Biotechnol 2014; 41:931-45. [PMID: 24664516 DOI: 10.1007/s10295-014-1431-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/26/2014] [Indexed: 12/16/2022]
Abstract
Inhibitors released by the breakdown of plant cell walls prevent efficient conversion of sugar into ethanol. The aim of this study was to develop a fast and reliable inhibitor sensitivity assay for ethanologenic yeast strains. The assay comprised bespoke 96-well plates containing inhibitors in isolation or combination in a format that was compatible with the Phenotypic Microarray Omnilog reader (Biolog, hayward, CA, USA). A redox reporter within the assay permits analysis of inhibitor sensitivity in aerobic and/or anaerobic conditions. Results from the assay were verified using growth on spot plates and tolerance assays in which maintenance of viability was assessed. The assay allows for individual and synergistic effects of inhibitors to be determined. It was observed that the presence of both acetic and formic acid significantly inhibited the yeast strains assessed, although this impact could be partially mitigated by buffering to neutral pH. Scheffersomyces stipitis, Candida spp., and Pichia guilliermondii demonstrated increased sensitivity to short chain weak acids at concentrations typically present in lignocellulosic hydrolysates. S. cerevisiae exhibited robustness to short chain weak acids at these concentrations. However, S. stipitis, Candida spp., and P. guilliermondii displayed increased tolerance to HMF when compared to that observed for S. cerevisiae. The results demonstrate that the phenotypic microarray assay developed in the current study is a valuable tool that can be used to identify yeast strains with desirable resistance to inhibitory compounds found in lignocellulosic hydrolysates.
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Affiliation(s)
- D Greetham
- Bioenergy and Brewing Science, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, Leicestershire, LE12 6RD, UK,
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Zha Y, Westerhuis JA, Muilwijk B, Overkamp KM, Nijmeijer BM, Coulier L, Smilde AK, Punt PJ. Identifying inhibitory compounds in lignocellulosic biomass hydrolysates using an exometabolomics approach. BMC Biotechnol 2014; 14:22. [PMID: 24655423 PMCID: PMC3998114 DOI: 10.1186/1472-6750-14-22] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/27/2014] [Indexed: 12/16/2022] Open
Abstract
Background Inhibitors are formed that reduce the fermentation performance of fermenting yeast during the pretreatment process of lignocellulosic biomass. An exometabolomics approach was applied to systematically identify inhibitors in lignocellulosic biomass hydrolysates. Results We studied the composition and fermentability of 24 different biomass hydrolysates. To create diversity, the 24 hydrolysates were prepared from six different biomass types, namely sugar cane bagasse, corn stover, wheat straw, barley straw, willow wood chips and oak sawdust, and with four different pretreatment methods, i.e. dilute acid, mild alkaline, alkaline/peracetic acid and concentrated acid. Their composition and that of fermentation samples generated with these hydrolysates were analyzed with two GC-MS methods. Either ethyl acetate extraction or ethyl chloroformate derivatization was used before conducting GC-MS to prevent sugars are overloaded in the chromatograms, which obscure the detection of less abundant compounds. Using multivariate PLS-2CV and nPLS-2CV data analysis models, potential inhibitors were identified through establishing relationship between fermentability and composition of the hydrolysates. These identified compounds were tested for their effects on the growth of the model yeast, Saccharomyces. cerevisiae CEN.PK 113-7D, confirming that the majority of the identified compounds were indeed inhibitors. Conclusion Inhibitory compounds in lignocellulosic biomass hydrolysates were successfully identified using a non-targeted systematic approach: metabolomics. The identified inhibitors include both known ones, such as furfural, HMF and vanillin, and novel inhibitors, namely sorbic acid and phenylacetaldehyde.
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Affiliation(s)
| | | | | | | | | | | | | | - Peter J Punt
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist 3704 HE, The Netherlands.
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45
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Zhang X, P. Nghiem N. Pretreatment and Fractionation of Wheat Straw for Production of Fuel Ethanol and Value-added Co-products in a Biorefinery. AIMS BIOENGINEERING 2014. [DOI: 10.3934/bioeng.2014.1.40] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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46
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Harnessing genetic diversity in Saccharomyces cerevisiae for fermentation of xylose in hydrolysates of alkaline hydrogen peroxide-pretreated biomass. Appl Environ Microbiol 2013; 80:540-54. [PMID: 24212571 DOI: 10.1128/aem.01885-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The fermentation of lignocellulose-derived sugars, particularly xylose, into ethanol by the yeast Saccharomyces cerevisiae is known to be inhibited by compounds produced during feedstock pretreatment. We devised a strategy that combined chemical profiling of pretreated feedstocks, high-throughput phenotyping of genetically diverse S. cerevisiae strains isolated from a range of ecological niches, and directed engineering and evolution against identified inhibitors to produce strains with improved fermentation properties. We identified and quantified for the first time the major inhibitory compounds in alkaline hydrogen peroxide (AHP)-pretreated lignocellulosic hydrolysates, including Na(+), acetate, and p-coumaric (pCA) and ferulic (FA) acids. By phenotyping these yeast strains for their abilities to grow in the presence of these AHP inhibitors, one heterozygous diploid strain tolerant to all four inhibitors was selected, engineered for xylose metabolism, and then allowed to evolve on xylose with increasing amounts of pCA and FA. After only 149 generations, one evolved isolate, GLBRCY87, exhibited faster xylose uptake rates in both laboratory media and AHP switchgrass hydrolysate than its ancestral GLBRCY73 strain and completely converted 115 g/liter of total sugars in undetoxified AHP hydrolysate into more than 40 g/liter ethanol. Strikingly, genome sequencing revealed that during the evolution from GLBRCY73, the GLBRCY87 strain acquired the conversion of heterozygous to homozygous alleles in chromosome VII and amplification of chromosome XIV. Our approach highlights that simultaneous selection on xylose and pCA or FA with a wild S. cerevisiae strain containing inherent tolerance to AHP pretreatment inhibitors has potential for rapid evolution of robust properties in lignocellulosic biofuel production.
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47
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Skerker JM, Leon D, Price MN, Mar JS, Tarjan DR, Wetmore KM, Deutschbauer AM, Baumohl JK, Bauer S, Ibáñez AB, Mitchell VD, Wu CH, Hu P, Hazen T, Arkin AP. Dissecting a complex chemical stress: chemogenomic profiling of plant hydrolysates. Mol Syst Biol 2013; 9:674. [PMID: 23774757 PMCID: PMC3964314 DOI: 10.1038/msb.2013.30] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 05/12/2013] [Indexed: 11/09/2022] Open
Abstract
Complex chemical stress arises during the production of biofuels. Large-scale mutant fitness profiling was used to identify bacterial and yeast tolerance genes and to model fitness in a complex hydrolysate mixture. The resulting model can be used to engineer more tolerant strains. ![]()
Genome-wide fitness profiling was used to identify plant hydrolysate tolerance genes in Zymomonas mobilis and Saccharomyces cerevisiae. We modeled fitness in hydrolysate as a mixture of fitness in its components. Outliers in our model led to the identification of a previously unknown component of hydrolysate. Overexpression of a Z. mobilis tolerance gene of unknown function improved ethanol productivity in plant hydrolysate.
The efficient production of biofuels from cellulosic feedstocks will require the efficient fermentation of the sugars in hydrolyzed plant material. Unfortunately, plant hydrolysates also contain many compounds that inhibit microbial growth and fermentation. We used DNA-barcoded mutant libraries to identify genes that are important for hydrolysate tolerance in both Zymomonas mobilis (44 genes) and Saccharomyces cerevisiae (99 genes). Overexpression of a Z. mobilis tolerance gene of unknown function (ZMO1875) improved its specific ethanol productivity 2.4-fold in the presence of miscanthus hydrolysate. However, a mixture of 37 hydrolysate-derived inhibitors was not sufficient to explain the fitness profile of plant hydrolysate. To deconstruct the fitness profile of hydrolysate, we profiled the 37 inhibitors against a library of Z. mobilis mutants and we modeled fitness in hydrolysate as a mixture of fitness in its components. By examining outliers in this model, we identified methylglyoxal as a previously unknown component of hydrolysate. Our work provides a general strategy to dissect how microbes respond to a complex chemical stress and should enable further engineering of hydrolysate tolerance.
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Affiliation(s)
- Jeffrey M Skerker
- Energy Biosciences Institute, University of California, Berkeley, CA, USA
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48
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Ludwig D, Amann M, Hirth T, Rupp S, Zibek S. Development and optimization of single and combined detoxification processes to improve the fermentability of lignocellulose hydrolyzates. BIORESOURCE TECHNOLOGY 2013; 133:455-461. [PMID: 23454802 DOI: 10.1016/j.biortech.2013.01.053] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/08/2013] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
In this work, an enzyme catalyzed detoxification process of lignocellulose hydrolyzates with immobilized laccase from Trametes versicolor was developed and optimized. Further, the immobilized laccase significantly reduced the amount of toxic phenolic compounds in the xylan rich fraction (XRF) by polymerization within 1h. The insoluble products precipitated onto the carrier surface and could be reversible resolubilized by an aqueous ethanol solution. Consequently, an in situ product removal could be realized. The reusability of the immobilized laccase could be additionally shown. The reaction kinetics could be described by a reversible Michaelis Menten equation giving the prerequisite for scaling up the process. In a second step, the organic acids, hydroxymethylfurfural and phenolic acids could be further removed by employing an anion exchanger. Both, the laccase and the laccase+anion exchanger treatment enhanced successfully the fermentability of an organosolv wheat straw fraction.
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Affiliation(s)
- Daniel Ludwig
- Evonik Industries AG Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang, Germany
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49
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Zha Y, Punt PJ. Exometabolomics approaches in studying the application of lignocellulosic biomass as fermentation feedstock. Metabolites 2013; 3:119-43. [PMID: 24957893 PMCID: PMC3901257 DOI: 10.3390/metabo3010119] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 12/13/2012] [Accepted: 01/28/2013] [Indexed: 11/16/2022] Open
Abstract
Lignocellulosic biomass is the future feedstock for the production of biofuel and bio-based chemicals. The pretreatment-hydrolysis product of biomass, so-called hydrolysate, contains not only fermentable sugars, but also compounds that inhibit its fermentability by microbes. To reduce the toxicity of hydrolysates as fermentation media, knowledge of the identity of inhibitors and their dynamics in hydrolysates need to be obtained. In the past decade, various studies have applied targeted metabolomics approaches to examine the composition of biomass hydrolysates. In these studies, analytical methods like HPLC, RP-HPLC, CE, GC-MS and LC-MS/MS were used to detect and quantify small carboxylic acids, furans and phenols. Through applying targeted metabolomics approaches, inhibitors were identified in hydrolysates and their dynamics in fermentation processes were monitored. However, to reveal the overall composition of different hydrolysates and to investigate its influence on hydrolysate fermentation performance, a non-targeted metabolomics study needs to be conducted. In this review, a non-targeted and generic metabolomics approach is introduced to explore inhibitor identification in biomass hydrolysates, and other similar metabolomics questions.
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Affiliation(s)
- Ying Zha
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist, 3704 HE, The Netherlands.
| | - Peter J Punt
- TNO Microbiology & Systems Biology, Utrechtsweg 48, Zeist, 3704 HE, The Netherlands.
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50
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Jönsson LJ, Alriksson B, Nilvebrant NO. Bioconversion of lignocellulose: inhibitors and detoxification. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:16. [PMID: 23356676 PMCID: PMC3574029 DOI: 10.1186/1754-6834-6-16] [Citation(s) in RCA: 611] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 01/16/2013] [Indexed: 05/17/2023]
Abstract
Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts.
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Affiliation(s)
- Leif J Jönsson
- Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden
| | - Björn Alriksson
- Processum Biorefinery Initiative AB, Örnsköldsvik, SE-891 22, Sweden
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