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Biofuel production from straw hydrolysates: current achievements and perspectives. Appl Microbiol Biotechnol 2019; 103:5105-5116. [PMID: 31081521 PMCID: PMC6570699 DOI: 10.1007/s00253-019-09863-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 12/15/2022]
Abstract
Straw is an agricultural residue of the production of e.g. cereals, rapeseed or sunflowers. It includes dried stalks, leaves, and empty ears and corncobs, which are separated from the grains during harvest. Straw is a promising lignocellulosic feedstock with a beneficial greenhouse gas balance for the production of biofuels and chemicals. Like all lignocellulosic materials, straw is recalcitrant and requires thermochemical and enzymatic pretreatment to enable access to the three major biopolymers of straw—the polysaccharides cellulose and hemicellulose and the polyaromatic compound lignin. Straw is used for commercial ethanol and biogas production. Considerable research has also been conducted to produce biobutanol, biodiesel and biochemicals from this raw material, but more research is required to establish them on a commercial scale. The major hindrance for launching industrial biofuel and chemicals’ production from straw is the high cost necessitated by pretreatment of the material. Improvements of microbial strains, production and extraction technologies, as well as co-production of high-value compounds represent ways of establishing straw as feedstock for the production of biofuels, chemicals and food.
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Brandenburg J, Poppele I, Blomqvist J, Puke M, Pickova J, Sandgren M, Rapoport A, Vedernikovs N, Passoth V. Bioethanol and lipid production from the enzymatic hydrolysate of wheat straw after furfural extraction. Appl Microbiol Biotechnol 2018; 102:6269-6277. [PMID: 29804136 PMCID: PMC6013517 DOI: 10.1007/s00253-018-9081-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/12/2018] [Indexed: 12/16/2022]
Abstract
This study investigates biofuel production from wheat straw hydrolysate, from which furfural was extracted using a patented method developed at the Latvian State Institute of Wood Chemistry. The solid remainder after furfural extraction, corresponding to 67.6% of the wheat straw dry matter, contained 69.9% cellulose of which 4% was decomposed during the furfural extraction and 26.3% lignin. Enzymatic hydrolysis released 44% of the glucose monomers in the cellulose. The resulting hydrolysate contained mainly glucose and very little amount of acetic acid. Xylose was not detectable. Consequently, the undiluted hydrolysate did not inhibit growth of yeast strains belonging to Saccharomyces cerevisiae, Lipomyces starkeyi, and Rhodotorula babjevae. In the fermentations, average final ethanol concentrations of 23.85 g/l were obtained, corresponding to a yield of 0.53 g ethanol per g released glucose. L. starkeyi generated lipids with a rate of 0.08 g/h and a yield of 0.09 g per g consumed glucose. R. babjevae produced lipids with a rate of 0.18 g/h and a yield of 0.17 per g consumed glucose. In both yeasts, desaturation increased during cultivation. Remarkably, the R. babjevae strain used in this study produced considerable amounts of heptadecenoic, α,- and γ-linolenic acid.
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Affiliation(s)
- Jule Brandenburg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Ieva Poppele
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Str., 1-537, Riga, LV-1004, Latvia
| | - Johanna Blomqvist
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Maris Puke
- Latvian State Institute of Wood Chemistry, Dzerbenes Str. 27/345, Riga, LV-1006, Latvia
| | - Jana Pickova
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Alexander Rapoport
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Str., 1-537, Riga, LV-1004, Latvia
| | - Nikolajs Vedernikovs
- Latvian State Institute of Wood Chemistry, Dzerbenes Str. 27/345, Riga, LV-1006, Latvia
| | - Volkmar Passoth
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden.
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Arous F, Atitallah IB, Nasri M, Mechichi T. A sustainable use of low-cost raw substrates for biodiesel production by the oleaginous yeast Wickerhamomyces anomalus. 3 Biotech 2017; 7:268. [PMID: 28794923 PMCID: PMC5534192 DOI: 10.1007/s13205-017-0903-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/24/2017] [Indexed: 10/19/2022] Open
Abstract
Over the past decade, the increasing demand of vegetable oils for biodiesel production has highlighted the need for alternative oil feedstocks that do not compete with food production. In this context, the combined use of agro-industrial wastes and oleaginous microorganisms could be a promising strategy for sustainable biodiesel production. The present investigation involves the performance of the oleaginous yeast Wickerhamomyces anomalus strain EC28 to produce lipids from different agro-industrial wastewaters (i.e., deproteinized cheese whey, olive mill wastewater, and wastewaters from confectionary industries) and waste frying oils (i.e., waste oil from frying fish, waste oil from frying potato and waste oil from frying meat). Results indicated that this strain can adequately grow on agro-industrial wastewater-based media and produce substantial amounts of lipids [up to 24%, wt/wt in deproteinized cheese whey-based medium and olive mill wastewater-based medium (75%, v/v in water)] of similar fatty acid composition to that of the most commonly used vegetable oils in the biodiesel industry. However, the addition of frying oils to the culture media resulted in a significant decrease in total lipid content, probably due to excess of available nitrogen released from meat, fish, and potato into the frying oil. The estimated properties of the resulting biodiesels, such as SV (190.69-203.13), IV (61.77-88.32), CN (53.45-59.32), and CFPP (-0.54 to 10.4), are reported, for the first time, for W. anomalus and correlate well with specified standards. In conclusion, W. anomalus strain EC28, for which there is very limited amount of available information, might be regarded as a promising candidate for biodiesel production and additional efforts for process improvement should be envisaged.
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Affiliation(s)
- Fatma Arous
- Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax (ENIS), University of Sfax, BP 1173, 3038 Sfax, Tunisia
- Laboratory of Microorganisms and Active Biomolecules, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Imen Ben Atitallah
- Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax (ENIS), University of Sfax, BP 1173, 3038 Sfax, Tunisia
| | - Moncef Nasri
- Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax (ENIS), University of Sfax, BP 1173, 3038 Sfax, Tunisia
| | - Tahar Mechichi
- Laboratory of Enzyme Engineering and Microbiology, National School of Engineering of Sfax (ENIS), University of Sfax, BP 1173, 3038 Sfax, Tunisia
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Production, Characterization, and Antimicrobial Activity of Mycocin Produced by Debaryomyces hansenii DSMZ70238. Int J Microbiol 2017; 2017:2605382. [PMID: 28757872 PMCID: PMC5512030 DOI: 10.1155/2017/2605382] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 04/25/2017] [Accepted: 05/21/2017] [Indexed: 11/29/2022] Open
Abstract
The present study was conducted to estimate the antimicrobial activity and the potential biological control of the killer toxin produced by D. hansenii DSMZ70238 against several pathogenic microorganisms. In this study, the effects of NaCl, pH, and temperature, killer toxin production, and antimicrobial activity were studied. The results showed that the optimum inhibitory effect of killer toxin was at 8% NaCl, and the diameters of clear zones were 20, 22, 22, 21, 14, and 13 mm for Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Streptococcus pyogenes, Candida albicans, and Candida neoformans, respectively. The largest inhibition zones were observed at pH 4.5 with inhibition zone of 16, 18, 17, 18, 11, and 12 mm for the same microorganisms. The results also showed that 25°C is the optimal temperature for toxin killing activity against all targeted microorganisms. In addition, the activity of killer toxin significantly inhibited the growth of fungal mycelia for all target pathogenic fungi and the percentages of inhibition were 47.77, 48.88, 52.22, and 61.11% for Trichophyton rubrum, Alternaria alternata, Trichophyton concentricum, and Curvularia lunata, respectively. The results showed the highest growth rate of D. hansenii DSMZ70238 under condition of 8% NaCl concentration, pH 4.5, and 25°C for 72 h.
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Kostas ET, White DA, Du C, Cook DJ. Selection of yeast strains for bioethanol production from UK seaweeds. JOURNAL OF APPLIED PHYCOLOGY 2016; 28:1427-1441. [PMID: 27057090 PMCID: PMC4789230 DOI: 10.1007/s10811-015-0633-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/24/2015] [Accepted: 05/24/2015] [Indexed: 05/13/2023]
Abstract
Macroalgae (seaweeds) are a promising feedstock for the production of third generation bioethanol, since they have high carbohydrate contents, contain little or no lignin and are available in abundance. However, seaweeds typically contain a more diverse array of monomeric sugars than are commonly present in feedstocks derived from lignocellulosic material which are currently used for bioethanol production. Hence, identification of a suitable fermentative microorganism that can utilise the principal sugars released from the hydrolysis of macroalgae remains a major objective. The present study used a phenotypic microarray technique to screen 24 different yeast strains for their ability to metabolise individual monosaccharides commonly found in seaweeds, as well as hydrolysates following an acid pre-treatment of five native UK seaweed species (Laminaria digitata, Fucus serratus, Chondrus crispus, Palmaria palmata and Ulva lactuca). Five strains of yeast (three Saccharomyces spp, one Pichia sp and one Candida sp) were selected and subsequently evaluated for bioethanol production during fermentation of the hydrolysates. Four out of the five selected strains converted these monomeric sugars into bioethanol, with the highest ethanol yield (13 g L-1) resulting from a fermentation using C. crispus hydrolysate with Saccharomyces cerevisiae YPS128. This study demonstrated the novel application of a phenotypic microarray technique to screen for yeast capable of metabolising sugars present in seaweed hydrolysates; however, metabolic activity did not always imply fermentative production of ethanol.
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Affiliation(s)
- Emily T. Kostas
- />The University of Nottingham, Sutton Bonington Campus, Bioenergy and Brewing Science Building, Loughborough, Leicestershire LE12 5RD UK
| | - Daniel A. White
- />Plymouth Marine Laboratory, Prospect Pl, Plymouth, Devon PL1 3DH UK
| | - Chenyu Du
- />The University of Nottingham, Sutton Bonington Campus, Bioenergy and Brewing Science Building, Loughborough, Leicestershire LE12 5RD UK
| | - David J. Cook
- />The University of Nottingham, Sutton Bonington Campus, Bioenergy and Brewing Science Building, Loughborough, Leicestershire LE12 5RD UK
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Theuretzbacher F, Blomqvist J, Lizasoain J, Klietz L, Potthast A, Horn SJ, Nilsen PJ, Gronauer A, Passoth V, Bauer A. The effect of a combined biological and thermo-mechanical pretreatment of wheat straw on energy yields in coupled ethanol and methane generation. BIORESOURCE TECHNOLOGY 2015; 194:7-13. [PMID: 26176820 DOI: 10.1016/j.biortech.2015.06.093] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Revised: 06/19/2015] [Accepted: 06/20/2015] [Indexed: 05/11/2023]
Abstract
Ethanol and biogas are energy carriers that could contribute to a future energy system independent of fossil fuels. Straw is a favorable bioenergy substrate as it does not compete with food or feed production. As straw is very resistant to microbial degradation, it requires a pretreatment to insure efficient conversion to ethanol and/or methane. This study investigates the effect of combining biological pretreatment and steam explosion on ethanol and methane yields in order to improve the coupled generation process. Results show that the temperature of the steam explosion pretreatment has a particularly strong effect on possible ethanol yields, whereas combination with the biological pretreatment showed no difference in overall energy yield. The highest overall energy output was found to be 10.86 MJ kg VS(-1) using a combined biological and steam explosion pretreatment at a temperature of 200°C.
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Affiliation(s)
- Franz Theuretzbacher
- University of Natural Resources and Life Sciences, Department of Sustainable Agricultural Systems, Institute of Agricultural Engineering, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria
| | - Johanna Blomqvist
- Swedish University of Agricultural Sciences, Uppsala BioCenter, Department of Chemistry and Biotechnology, P.O. Box 7015, 750 07 Uppsala, Sweden
| | - Javier Lizasoain
- University of Natural Resources and Life Sciences, Department of Sustainable Agricultural Systems, Institute of Agricultural Engineering, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria; alpS - Centre for Climate Change Adaptation, Grabenweg 68, A-6010 Innsbruck, Austria
| | - Lena Klietz
- alpS - Centre for Climate Change Adaptation, Grabenweg 68, A-6010 Innsbruck, Austria
| | - Antje Potthast
- University of Natural Resources and Life Sciences, Department of Chemistry, Division of Organic Chemistry, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria
| | - Svein Jarle Horn
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway
| | | | - Andreas Gronauer
- University of Natural Resources and Life Sciences, Department of Sustainable Agricultural Systems, Institute of Agricultural Engineering, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria
| | - Volkmar Passoth
- Swedish University of Agricultural Sciences, Uppsala BioCenter, Department of Microbiology, P.O. Box 7025, 750 07 Uppsala, Sweden
| | - Alexander Bauer
- University of Natural Resources and Life Sciences, Department of Sustainable Agricultural Systems, Institute of Agricultural Engineering, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
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Cray JA, Stevenson A, Ball P, Bankar SB, Eleutherio ECA, Ezeji TC, Singhal RS, Thevelein JM, Timson DJ, Hallsworth JE. Chaotropicity: a key factor in product tolerance of biofuel-producing microorganisms. Curr Opin Biotechnol 2015; 33:228-59. [PMID: 25841213 DOI: 10.1016/j.copbio.2015.02.010] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 02/13/2015] [Accepted: 02/18/2015] [Indexed: 10/23/2022]
Abstract
Fermentation products can chaotropically disorder macromolecular systems and induce oxidative stress, thus inhibiting biofuel production. Recently, the chaotropic activities of ethanol, butanol and vanillin have been quantified (5.93, 37.4, 174kJ kg(-1)m(-1) respectively). Use of low temperatures and/or stabilizing (kosmotropic) substances, and other approaches, can reduce, neutralize or circumvent product-chaotropicity. However, there may be limits to the alcohol concentrations that cells can tolerate; e.g. for ethanol tolerance in the most robust Saccharomyces cerevisiae strains, these are close to both the solubility limit (<25%, w/v ethanol) and the water-activity limit of the most xerotolerant strains (0.880). Nevertheless, knowledge-based strategies to mitigate or neutralize chaotropicity could lead to major improvements in rates of product formation and yields, and also therefore in the economics of biofuel production.
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Affiliation(s)
- Jonathan A Cray
- Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Andrew Stevenson
- Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - Philip Ball
- 18 Hillcourt Road, East Dulwich, London SE22 0PE, UK
| | - Sandip B Bankar
- Department of Chemical Engineering, College of Engineering, Bharati Vidyapeeth University, Pune-Satara Road, Pune 411043, India
| | - Elis C A Eleutherio
- Universidade Federal do Rio de Janeiro, Instituto de Quimica, Programa de Pós-graduação Bioquimica, Rio de Janeiro, RJ, Brazil
| | - Thaddeus C Ezeji
- Department of Animal Sciences and Ohio Agricultural Research and Development Center (OARDC), The Ohio State University, 305 Gerlaugh Hall, 1680 Madison Avenue, Wooster, OH 44691, USA
| | - Rekha S Singhal
- Department of Food Engineering and Technology, Institute of Chemical Technology, N.P. Marg, Matunga, Mumbai, Maharashtra 400019, India
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven and Department of Molecular Microbiology, VIB, Kasteelpark Arenberg 31, Flanders, Leuven-Heverlee B-3001, Belgium
| | - David J Timson
- Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | - John E Hallsworth
- Institute for Global Food Security, School of Biological Sciences, MBC, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK.
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Rapoport A, Heipieper HJ. Biotechnological and environmental microbiological research in the Baltic region. Biotechnol Appl Biochem 2014; 61:1-2. [PMID: 24527730 DOI: 10.1002/bab.1210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 01/23/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Alexander Rapoport
- Laboratory of Cell Biology, Institute of Microbiology and Biotechnology, University of Latvia, Riga, Latvia
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Blomqvist J, Leong SLL, Sandgren M, Lestander T, Passoth V. Temperature-dependent changes in the microbial storage flora of birch and spruce sawdust. Biotechnol Appl Biochem 2014; 61:58-64. [PMID: 24527731 DOI: 10.1002/bab.1153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 09/03/2013] [Indexed: 11/09/2022]
Abstract
Sawdust can be used to make pellets (biofuel) and particle boards and as a potential lignocellulose feedstock in bioethanol production. Microbial activity can affect sawdust quality; hence, we monitored the microbial population in birch- and spruce sawdust after 3 months' storage at various temperatures. Species composition was similar on both materials but was strongly influenced by temperature. Bacteria were present on all materials at all conditions: on birch, 2.8 × 10(8) , 1.1 × 10(8) , and 8.8 × 10(6) , and on spruce, 4.1 × 10(8) , 5.6 × 10(7) , and 1.5 × 10(8) CFU/g DM, at 2, 20, and 37 °C, respectively. Dominant bacteria at 2, 20, and 37 °C were Pseudomonas spp. (some Enterobacteriaceae spp. present), Luteibacter rhizovicinus, and Fulvimonas sp., respectively. Pseudomonas spp. were absent at ≥20 °C. Among microfungi, yeasts dominated at 2 °C but were absent at 37 °C, whereas molds dominated at 20 and 37 °C. Common yeasts included Cystofilobasidium capitatum, Cystofilobasidium infirmominiatum, Candida saitoana, Candida oregonensis, and Candida railenensis. Ophiostoma quercus was a common mold at 2 and 20 °C, whereas the human pathogens Aspergillus fumigatus and Paecilomyces variotii dominated at 37 °C. Attempts to influence the microflora by addition of the biocontrol yeasts, Wickerhamomyces anomalus and Scheffersomyces stipitis, were unsuccessful, as their growth in sawdust was poor to absent.
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Affiliation(s)
- Johanna Blomqvist
- Swedish University of Agricultural Sciences, Uppsala BioCenter, Department of Microbiology, Uppsala, Sweden
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Enhanced ethanol and chitosan production from wheat straw by Mucor indicus with minimal nutrient consumption. Process Biochem 2013. [DOI: 10.1016/j.procbio.2013.07.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Waste valorization by biotechnological conversion into added value products. Appl Microbiol Biotechnol 2013; 97:6129-47. [DOI: 10.1007/s00253-013-5014-7] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 11/25/2022]
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Ambye-Jensen M, Thomsen ST, Kádár Z, Meyer AS. Ensiling of wheat straw decreases the required temperature in hydrothermal pretreatment. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:116. [PMID: 23945109 PMCID: PMC3751596 DOI: 10.1186/1754-6834-6-116] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Accepted: 07/22/2013] [Indexed: 05/11/2023]
Abstract
BACKGROUND Ensiling is a well-known method for preserving green biomasses through anaerobic production of organic acids by lactic acid bacteria. In this study, wheat straw is subjected to ensiling in combination with hydrothermal treatment as a combined pretreatment method, taking advantage of the produced organic acids. RESULTS Ensiling for 4 weeks was accomplished in a vacuum bag system after addition of an inoculum of Lactobacillus buchneri and 7% w/w xylose to wheat straw biomass at 35% final dry matter. Both glucan and xylan were preserved, and the DM loss after ensiling was less than 0.5%. When comparing hydrothermally treated wheat straw (170, 180 and 190°C) with hydrothermally treated ensiled wheat straw (same temperatures), several positive effects of ensiling were revealed. Glucan was up-concentrated in the solid fraction and the solubilisation of hemicellulose was significantly increased. Subsequent enzymatic hydrolysis of the solid fractions showed that ensiling significantly improved the effect of pretreatment, especially at the lower temperatures of 170 and 180°C. The overall glucose yields after pretreatments of ensiled wheat straw were higher than for non-ensiled wheat straw hydrothermally treated at 190°C, namely 74-81% of the theoretical maximum glucose in the raw material, which was ~1.8 times better than the corresponding yields for the non-ensiled straw pretreated at 170 or 180°C. The highest overall conversion of combined glucose and xylose was achieved for ensiled wheat straw hydrothermally treated at 180°C, with overall glucose yield of 78% and overall conversion yield of xylose of 87%. CONCLUSIONS Ensiling of wheat straw is shown to be an effective pre-step to hydrothermal treatment, and can give rise to a welcomed decrease of process temperature in hydrothermal treatments, thereby potentially having a positive effect on large scale pretreatment costs.
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Affiliation(s)
- Morten Ambye-Jensen
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, DTU, Denmark
| | - Sune Tjalfe Thomsen
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, DTU, Denmark
| | - Zsófia Kádár
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, DTU, Denmark
| | - Anne S Meyer
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, DTU, Denmark
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