Ensiling and hydrothermal pretreatment of grass: consequences for enzymatic biomass conversion and total monosaccharide yields

Biotechnology for Biofuels

Morten Ambye-Jensen³  Katja S Johansen²  Thomas Didion¹  Zsófia Kádár³  Anne S Meyer³ 

[1] Danish Plant Breeding Research Division, DLF TRIFOLIUM A/S, Højerupvej 31, DK-4660 Store Heddinge, Denmark

[2] Novozymes A/S, Krogshøjvej 36, DK-2880 Bagsværd, Denmark

[3] Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs Lyngby, Denmark

关键词: Enzymatic hydrolysis;    Grass;    Hydrothermal treatment;    Combined pretreatment;    Ensiling;    Silage;   

Others  :  1084937
DOI  :  10.1186/1754-6834-7-95

 received in 2014-04-07, accepted in 2014-05-30,  发布年份 2014

【 摘 要 】

Background

Ensiling may act as a pretreatment of fresh grass biomass and increase the enzymatic conversion of structural carbohydrates to fermentable sugars. However, ensiling does not provide sufficient severity to be a standalone pretreatment method. Here, ensiling of grass is combined with hydrothermal treatment (HTT) with the aim of improving the enzymatic biomass convertibility and decrease the required temperature of the HTT.

Results

Grass silage (Festulolium Hykor) was hydrothermally treated at temperatures of 170, 180, and 190°C for 10 minutes. Relative to HTT treated dry grass, ensiling increased the solubilization of dry matter (DM) during HTT and gave increased glucan content, but lower lignin in the insoluble fiber fraction. Ensiling improved glucose yields in the enzymatic hydrolysis of the washed solid fiber fraction at the lower HTT temperatures. At 170°C glucose yield improved from 17 to 24 (w/w)% (45 to 57% cellulose convertibility), and at 180°C glucose yield improved from 22 to 29 (w/w)% (54 to 69% cellulose convertibility). Direct HTT of grass at 190°C gave the same high glucose yield as for grass silage (35 (w/w)% (77% cellulose convertibility)) and improved xylan yields (27% xylan convertibility). The effect of ensiling of grass prior to HTT improved the enzymatic conversion of cellulose for HTT at 170 and 180°C, but the increased glucose release did not make up for the loss of water soluble carbohydrates (WSC) during ensiling. Overall, sugar yields (C6 + C5) were similar for HTT of grass and grass silage at both 170 and 180°C, but at 190°C the overall sugar yield was better for HTT of dry grass.

Conclusions

This study unequivocally establishes that ensiling of grass as a biomass pretreatment method comes with a loss of WSC. The loss of WSC by ensiling is not necessarily compensated for by providing a lower temperature requirement for HTT for high enzymatic monosaccharide release. However, ensiling can be an advantageous storage method prior to grass processing.

【 授权许可】

   
2014 Ambye-Jensen et al.; licensee BioMed Central Ltd.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

【 参考文献 】

• [1]DIRECTIVE 2009/28/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC [2009] OJ L 140 5.6.2009, 16.
• [2]Proposal for a DIRECTIVE OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL amending Directive 98/70/EC relating to the quality of petrol and diesel fuels and amending Directive 2009/28/EC on the promotion of the use of energy from renewable sources Brussels; 2012. 17.10.2012 COM(2012) 595 final 2012/0288 (COD)
• [3]Allen BR, Keegan D, Elbersen B: Biomass and bioenergy in the wider land-use context of the European Union. Biofuels Bioprod Bioref 2013, 7(2):207-216.
• [4]Tilman D, Hill J, Lehman C: Carbon-negative biofuels from low-input high-diversity grassland biomass. Science 2006, 314(5805):1598-1600.
• [5]Buxton DR, Muck RE, Harrison JH: Silage science and technology. Wisonsin: American Society of Agronomy, Inc. Crop Science Society of America, Inc. Soil Science Society of America, Inc; 2003.
• [6]Rooke JA, Hatfield RD: Biochemistry of ensiling. In Silage science and technology. Edited by Buxton DR, Muck RE, Harrison JH. Wisconsin: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America; 2003:95-140.
• [7]Yang HY, Wang XF, Liu JB, Gao LJ, Ishii M, Igarashi Y, Cui ZJ: Effects of water-soluble carbohydrate content on silage fermentation of wheat straw. J Biosci Bioeng 2006, 101(3):232-237.
• [8]Ren H, Richard TL, Moore KJ: The impact of enzyme characteristics on corn stover fiber degradation and acid production during ensiled storage. Appl Biochem Biotechnol 2007, 137–140(1–12):221-238.
• [9]Larsen J, Haven MT, Thirup L: Inbicon makes lignocellulosic ethanol a commercial reality. Biomass Bioenergy 2012, 46:36-45.
• [10]Zhang PF, Zhang Q, Pei ZJ, Wang DH: Cost estimates of cellulosic ethanol production: a review. J Manuf Sci Eng 2013, 135(2):021005.
• [11]Festel G, Würmseher M, Rammer C, Boles E, Bellof M: Modelling production cost scenarios for biofuels and fossil fuels in Europe. J Clean Prod 2014, 66:242-253.
• [12]Yang B, Wyman CE: Pretreatment: the key to unlocking low-cost cellulosic ethanol. Biofuels Bioprod Bioref 2008, 2(1):26-40.
• [13]Bals B, Wedding C, Balan V, Sendich E, Dale B: Evaluating the impact of ammonia fiber expansion (AFEX) pretreatment conditions on the cost of ethanol production. Bioresour Technol 2011, 102(2):1277-1283.
• [14]Chen Y, Sharma-Shivappa RR, Chen C: Ensiling agricultural residues for bioethanol production. Appl Biochem Biotechnol 2007, 143(1):80-92.
• [15]Digman MF, Shinners KJ, Casler MD, Dien BS, Hatfield RD, Jung H-JG, Muck RE, Weimer PJ: Optimizing on-farm pretreatment of perennial grasses for fuel ethanol production. Bioresour Technol 2010, 101(14):5305-5314.
• [16]Oleskowicz-Popiel P, Thomsen AB, Schmidt JE: Ensiling - wet-storage method for lignocellulosic biomass for bioethanol production. Biomass Bioenergy 2011, 35(5):2087-2092.
• [17]Pakarinen A, Maijala P, Jaakkola S, Stoddard F, Kymäläinen M, Viikari L: Evaluation of preservation methods for improving biogas production and enzymatic conversion yields of annual crops. Biotechnol Biofuels 2011, 4(1):20.
• [18]Ambye-Jensen M, Johansen KS, Didion T, Kádár Z, Schmidt JE, Meyer AS: Ensiling as biological pretreatment of grass (festulolium hykor): the effect of composition, dry matter, and inocula on cellulose convertibility. Biomass Bioenergy 2013, 58:303-312.
• [19]Galbe M, Zacchi G: Pretreatment: the key to efficient utilization of lignocellulosic materials. Biomass Bioenergy 2012, 46:70-78.
• [20]Pedersen M, Meyer AS: Lignocellulose pretreatment – understanding biomatrix opening in relation to temperature and pH during pretreatment. New Biotechnol 2010, 27(6):739-750.
• [21]Hansen MAT, Kristensen JB, Felby C, Jørgensen H: Pretreatment and enzymatic hydrolysis of wheat straw (Triticum aestivum L.) - the impact of lignin relocation and plant tissues on enzymatic accessibility. Bioresour Technol 2011, 102(3):2804-2811.
• [22]Ambye-Jensen M, Thomsen ST, Kádár Z, Meyer AS: Ensiling of wheat straw decreases the required temperature in hydrothermal pretreatment. Biotechnol Biofuels 2013, 6(1):116.
• [23]Dewar WA, McDonald P, Whittenbury R: The hydrolysis of grass hemicelluloses during ensilage. J Sci Food Agric 1963, 14(6):411-417.
• [24]Morrison IM: Changes in the lignin and hemicellulose concentrations of 10 varieties of temperate grasses with increasing maturity. Grass Forage Sci 1980, 35(4):287-293.
• [25]Pahlow G, Muck RE, Driehuis F, Elferink SJWHO, Spoelstra SF: Microbiology of ensiling. In Silage science and technology. Edited by Buxton DR, Muck RE, Harrison JH. Wisconsin: American Society of Agronomy, Crop Science Society of America, Soil Science Society of America; 2003:31-94.
• [26]Jørgensen H, Vibe-Pedersen J, Larsen J, Felby C: Liquefaction of lignocellulose at high-solids concentrations. Biotechnol Bioeng 2007, 96(5):862-870.
• [27]Graves T, Narendranath NV, Dawson K, Power R: Effect of pH and lactic or acetic acid on ethanol productivity by Saccharomyces cerevisiae in corn mash. J Ind Microbiol Biotechnol 2006, 33(6):469-474.
• [28]Kont R, Kurašin M, Teugjas H, Väljamäe P: Strong cellulase inhibitors from the hydrothermal pretreatment of wheat straw. Biotechnol Biofuels 2013, 6(1):135.
• [29]Kumar R, Hu F, Sannigrahi P, Jung S, Ragauskas AJ, Wyman CE: Carbohydrate derived-pseudo-lignin can retard cellulose biological conversion. Biotechnol Bioeng 2013, 110(3):737-753.
• [30]Klinke HB, Thomsen AB, Ahring BK: Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. Appl Microbiol Biotechnol 2004, 66(1):10-26.
• [31]Scheller HV, Ulvskov P: Hemicelluloses. Annu Rev Plant Biol 2010, 61:263-289.
• [32]Yu P, McKinnon JJ, Christensen DA: Hydroxycinnamic acids and ferulic acid esterase in relation to biodegradation of complex plant cell walls. Can J Anim Sci 2005, 85(3):255-267.
• [33]Xu F, Geng ZC, Sun JX, Liu CF, Ren JL, Sun RC, Fowler P, Baird MS: Fractional and structural characterization of hemicelluloses from perennial ryegrass (Lolium perenne) and cocksfoot grass (Dactylis glomerata). Carbohydr Res 2006, 341(12):2073-2082.
• [34]Quinlan RJ, Sweeney MD, Lo Leggio L, Otten H, Poulsen J-CN, Johansen KS, Krogh KBRM, Jørgensen CI, Tovborg M, Anthonsen A, Tryfona T, Walter CP, Dupree P, Xu F, Davies GJ, Walton PH: Insights into the oxidative degradation of cellulose by a copper metalloenzyme that exploits biomass components. Proc Natl Acad Sci USA 2011, 108(37):15079-15084.
• [35]Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D, Crocker D: Determination of structural carbohydrates and lignin in biomass. NREL Technical Report 2011. NREL/TP-510-42618 (Version 07.08.2011). National Renewable Energy Laboratory; 1 (Boulder, Colorado)
• [36]Sluiter A, Hames B, Hyman D, Payne C, Ruiz R, Scarlata C, Sluiter J, Templeton D, Wolfe J: Determination of total solids in biomass and total dissolved solids in liquid process samples. NREL Technical Report 2008. NREL/TP-510-42621 (Version 03.31.2008). National Renewable Energy Laboratory; 1. (Boulder, Colorado)
• [37]Huida L, Väätäinen H, Lampila L: Comparison of dry-matter contents in grass silages as determined by oven drying and gas-chromatographic water analysis. Ann Agr Fen 1986, 25(3):215-230.