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1.
A novel process using chemical, thermal, and enzymatic treatment for conversion of hulled barley into fermentable sugars was
developed. The purpose of this process is to convert both lignocellulosic polysaccharides and starch in hulled barley grains
into fermentable sugars simultaneously without a need for grinding and hull separation. In this study, hulled barley grains
were treated with 0.1 and 1.0 wt.-% sulfuric acid at various temperatures ranging from 110 to 170 °C in a 63-ml flow-through
packed-bed stainless steel reactor. After sulfuric acid pretreatment, simultaneous conversion of lignocellulose and starch
in the barley grains into fermentable sugars was performed using an enzyme cocktail, which included α-amylase, glucoamylase,
cellulase, and β-glucosidase. Both starch and non-starch polysaccharides in the pre-treated barley grains were readily converted
to fermentable sugars. The treated hulled barley grains, including their hull, were completely hydrolyzed to fermentable sugars
with recovery of almost 100% of the available glucose and xylose. The pretreatment conditions of this chemical, thermal, and
enzymatic (CTE) process for achieving maximum yield of fermentable sugars were 1.0 wt.% sulfuric acid and 110 °C. In addition
to starch, the acid pretreatment also retained most of the available proteins in solid form, which is essential for subsequent
production of fuel ethanol and high protein distiller’s dried grains with solubles co-product. 相似文献
2.
Saha Badal C. Dien Bruce S. Bothast Rodney J. 《Applied biochemistry and biotechnology》1998,(1):115-125
Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low
cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant
technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment
procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms
to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber
cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined
for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed
for use in pretreated corn fiber saccharification.
Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
3.
Pretreatment of switchgrass by ammonia fiber explosion (AFEX) 总被引:3,自引:0,他引:3
Hasan Alizadeh Farzaneh Teymouri Thomas I. Gilbert Bruce E. Dale 《Applied biochemistry and biotechnology》2005,124(1-3):1133-1141
The effects of ammonia fiber explosion (AFEX) pretreatment of switch grass using its major process variables are reported.
The optimal pretreatment conditions for switchgrass were found to be near 100°C reactor temperature, and ammonia loading of
1:1 kg of ammonia: kg of dry matter with 80% moisture content (dry weight basis [dwb]) at 5 min residence time. Hydrolysis
results of AFEX-treated and untreated samples showed 93% vs 16% glucan conversion, respectively. The ethanol yield of optimized
AFEX-treated switchgrass was measured to be about 0.2 g ethanol/g dry biomass, which is 2.5 times more than that of the untreated
sample. 相似文献
4.
Lignocellulosic materials, such as forestry, agricultural and agroindustrial residues, are among the most important sources of biomass for the production of fuels, chemicals and materials. However there are physical and chemical barriers in the lignin–carbohydrate supramolecular structure that render most plant cell wall components almost completely unavailable for conversion into commercial products. Thus successful conversion strategies must lead to the disruption of this structure and result in partial or total separation of the lignocellulosic components, increasing the accessibility of cellulose, hemicelluloses and lignins. It must also minimize the formation of by-products. Each pretreatment technology has its own characteristics and is usually applied to a specific source of carbohydrates and lignins. A general overview of the most important pretreatment methods for the production of platform chemicals and fermentable sugars are given in this paper. 相似文献
5.
Farzaneh Teymouri Hasan Alizadeh Lizbeth Laureano-Pérez Bruce Dale Mariam Sticklen 《Applied biochemistry and biotechnology》2004,116(1-3):1183-1191
A critical parameter affecting the economic feasibility of lignocellulosic bioconversion is the production of inexpensive
and highly active cellulase enzymes in bulk quantity. A promising approach to reduce enzyme costs is to genetically transform
plants with the genes of these enzymes, thereby producing the desired cellulases in the plants themselves. Extraction and
recovery of active proteins or release of active cellulase from the plants during bioconversion could have a significant positive
impact on overall lignocellulose conversion economics. The effects of ammonia fiber explosion (AFEX) pretreatment variables
(treatment temperature, moisture content, and ammonia loading) on the activity of plant-produced heterologous cellulase enzyme
were individually investigated via heat treatmett or ammonia treatment. Finally, we studied the effects of all these variables
in concert through the AFEX process. The plant materials included transgenic tobacco plants expressing E1 (endoglucanase from
Acidothermus cellulolyticus). The E1 activity was measured in untreated and AFEX-treated tobacco leaves to investigate the effects of the treatment on
the activity of this enzyme. The maximum observed activity retention in AFEX-treated transgenic tobacco samples compared with
untreated samples was approx 35% (at 60°C, 0.5∶1 ammonia loading, and 40% moisture). Based on these findings, it is our opinion
that AFEX pretreatment is not a suitable option for releasing cellulase enzyme from transgenic plants. 相似文献
6.
Zheng Y Pan Z Zhang R Wang D Jenkins B 《Applied biochemistry and biotechnology》2008,146(1-3):231-248
Our previous research has shown that saline Creeping Wild Ryegrass (CWR), Leymus triticoides, has a great potential to be used for bioethanol production because of its high fermentable sugar yield, up to 85% cellulose
conversion of pretreated CWR. However, the high cost of enzyme is still one of the obstacles making large-scale lignocellulosic
bioethanol production economically difficult. It is desirable to use reduced enzyme loading to produce fermentable sugars
with high yield and low cost. To reduce the enzyme loading, the effect of addition of non-ionic surfactants and non-catalytic
protein on the enzymatic hydrolysis of pretreated CWR was investigated in this study. Tween 20, Tween 80, and bovine serum
albumin (BSA) were used as additives to improve the enzymatic hydrolysis of dilute sulfuric-acid-pretreated CWR. Under the
loading of 0.1 g additives/g dry solid, Tween 20 was the most effective additive, followed by Tween 80 and BSA. With the addition
of Tween 20 mixed with cellulase loading of 15 FPU/g cellulose, the cellulose conversion increased 14% (from 75 to 89%), which
was similar to that with cellulase loading of 30 FPU/g cellulose and without additive addition. The results of cellulase and
BSA adsorption on the Avicel PH101, pretreated CWR, and lignaceous residue of pretreated CWR support the theory that the primary
mechanism behind the additives is prevention of non-productive adsorption of enzymes on lignaceous material of pretreated
CWR. The addition of additives could be a promising technology to improve the enzymatic hydrolysis by reducing the enzyme
activity loss caused by non-productive adsorption. 相似文献
7.
Optimization of steam pretreatment of corn stover to enhance enzymatic digestibility 总被引:5,自引:0,他引:5
Among the available agricultural byproducts, corn stover, with its yearly production of 10 million t (dry basis), is the most
abundant promising raw material for fuel ethanol production in Hungary. In the United States, more than 216 million to fcorn
stover is produced annually, of which a portion also could possibly be collected for conversion to ethanol. However, a network
of lignin and hemicellulose protects cellulose, which is the major source of fermentable sugars in corn stover (approx 40%
of the dry matter [DM]). Steam pretreatment removes the major part of the hemicellulose from the solid material and makes
the cellulose more susceptible to enzymatic digestion. We studied 12 different combinations of reaction temperature, time,
and pH during steam pretreatment. The best conditions (200°C, 5 min, 2% H2SO4) increased the enzymatic conversion (from cellulose to glucose) of corn stover more then four times, compared to untreated
material. However, steam pretreatment at 190°C for 5 min with 2% sulfuric acid resulted in the highest overall yield of sugars,
56.1 g from 100 g of untreated material (DM), corresponding to 73% of the theoretical. The liquor following steam explosion
was fermented using Saccharomyces cerevisiae to investigate the inhibitory effect of the pretreatment. The achieved ethanol yield was slightly higher than that obtained
with a reference sugar solution. This demonstrates that baker's yeast could adapt to the pretreated liquor and ferment the
glucose to ethanol efficiently. 相似文献
8.
Bruce E. Dale Justin Weaver F. Michael Byers 《Applied biochemistry and biotechnology》1999,77(1-3):35-45
The ammonia fiber explosion (AFEX) process, previously run only in a batch reactor, has been adapted to run on a twin-screw
extruder. The sugar yield of AFEX material after enzymatic hydrolysis has been increased up to 3.5 times over that of completely
untreated material. The ruminant digestibility of corn fodder has been increased up to 32% (from 54–71%) over completely untreated
material, and 23% (from 63–77%) over material extruded with no ammonia. Extrusion-treated material proved more digestible
by the ruminant at 48 h than material treated in the batch reactor. 相似文献
9.
Suh Cem Pang Lee Ken Voon Suk Fun Chin 《Applied biochemistry and biotechnology》2018,184(4):1142-1154
The conversion of starchy sago (Metroxylon sagu) pith waste (SPW), a lignocellulosic biomass waste, to fermentable sugars under mild conditions had been successfully demonstrated. The optimum depolymerization of SPW was achieved at 2 wt% sample loading which was catalyzed by 100 mM of oxalic acid in the presence of 25 wt% NaCl solution at 110 °C for 3 h. Up to 97% SPW sample was being converted into fermentable sugars with limited formation of by-products after two sequential depolymerization cycles. Both reaction temperature and concentration of oxalic acid were crucial parameters for the depolymerization of SPW which exhibited a high selectivity for the production of glucose over other reducing sugars. 相似文献
10.
Belkacemi Khaled Turcotte Ginette Halleux Damien de Savoie Philippe 《Applied biochemistry and biotechnology》1998,(1):441-462
Lignocellulosic materials derived from forages, namely timothy grass, alfalfa, reed canary grass, and agricultural residues,
such as corn stalks and barley straw, were pretreated using ammonia fiber explosion (AFEX) process. The pretreated materials
were directly saccharified by cellulolytic enzymes. Sixty to 80% of theoretical yield of sugars were obtained from the pretreated
biomasses. Subsequent ethanolic fermentation of the hydrolysates byPachysolen tannophilus ATCC 32691 resulted in 40-60% of theoretical yield after 24 h, based on the sugars present in the hydrolysates. The uptake
of sugars was not complete, indicating a possible inhibitory effect onP. tannophilus during the fermentation of these substrates. 相似文献
11.
S. Linggang L. Y. Phang M. H. Wasoh S. Abd-Aziz 《Applied biochemistry and biotechnology》2012,167(1):122-131
Sago pith residue is one of the most abundant lignocellulosic biomass which can serve as an alternative cheap substrate for fermentable sugars production. This residue is the fibrous waste left behind after the starch extraction process and contains significant amounts of starch (58%), cellulose (23%), hemicellulose (9.2%) and lignin (3.9%). The conversion of sago pith residue into fermentable sugars is commonly performed using cellulolytic enzymes or known as cellulases. In this study, crude cellulases were produced by two local isolates, Trichoderma asperellum UPM1 and Aspergillus fumigatus, UPM2 using sago pith residue as substrate. A. fumigatus UPM2 gave the highest FPase, CMCase and ??-glucosidase activities of 0.39, 23.99 and 0.78 U/ml, respectively, on day 5. The highest activity of FPase, CMCase and ??-glucosidase by T. asperellum UPM1 was 0.27, 12.03 and 0.42 U/ml, respectively, on day 7. The crude enzyme obtained from A. fumigatus UPM2 using ??-glucosidase as the rate-limiting enzyme (3.9, 11.7 and 23.4?IU) was used for the saccharification process to convert 5% (w/v) sago pith residue into reducing sugars. Hydrolysis of sago pith residue using crude enzyme containing ??-glucosidase with 23.4?IU, produced by A. fumigatus UPM2 gave higher reducing sugars production of 20.77?g/l with overall hydrolysis percentage of 73%. 相似文献
12.
Switchgrass (Panicum vergatum) is a potential feedstock for future cellulosic biorefineries. Such a feedstock may also provide protein, most likely for
use as an animal feed. In this paper, we present a potential scheme for integrating fiber processing with extractions to obtain
both sugar and protein products from switchgrass pretreated using Ammonia Fiber Expansion (AFEX). Solutions of 3% aqueous
ammonia at pH 10.5 provided optimal extraction of proteins. Addition of the nonionic surfactant Tween-80 improved protein
recovery for AFEX-treated materials. It was determined that an extraction following AFEX solubilized approximately 40% of
the protein, while a subsequent hydrolysis solubilized much of the remaining protein while producing 325 g sugar per kg biomass.
The remaining insoluble residue contained very little protein or ash, making it ideal for heat and power production. In contrast,
an extraction following hydrolysis solubilized only 68% of the original protein in the biomass, while obtaining slightly higher
sugar yields. 相似文献
13.
Saprativ P. Das Rajeev Ravindran Shadab Ahmed Debasish Das Dinesh Goyal Carlos M. G. A. Fontes Arun Goyal 《Applied biochemistry and biotechnology》2012,167(6):1475-1488
The enhancement of the biomass productivity of Escherichia coli cells harbouring the truncated 903?bp gene designated as glycoside hydrolase family 43 (GH43) from Clostridium thermocellum showing hemicellulase activity along with its further use in simultaneous saccharification and fermentation (SSF) process is described. (Phosphoric acid) H3PO4?Cacetone treatment and ammonia fibre expansion (AFEX) were the pretreatment strategies employed on the leafy biomass of mango, poplar, neem and asoka among various substrates owing to their high hemicellulose content. GH43 showed optimal activity at a temperature of 50?°C, pH?5.4 with stability over a pH range of 5.0?C6.2. A 4-fold escalation in growth of the recombinant E. coli cells was observed when grown using repeated batch strategy in LB medium supplemented with glucose as co-substrate. Candida shehatae utilizing pentose sugars was employed for bioethanol production. AFEX pretreatment proved to be better over acid?Cacetone technique. The maximum ethanol concentration (1.44?g/L) was achieved for AFEX pretreated mango (1%, w/v) followed by poplar with an ethanol titre (1.32?g/L) in shake flask experiments. A 1.5-fold increase in ethanol titre (2.11?g/L) was achieved with mango (1%, w/v) in a SSF process using a table top 2-L bioreactor with 1?L working volume. 相似文献
14.
Corn stover, the most abundant agricultural residue in Hungary, is a potential raw material for the production of fuel ethanol
as a result of its high content of carbohydrates, but a pretreatment is required for its efficient hydrolysis. In this article,
we describe the results using various chemicals such as dilute H2SO4, HCl, and NaOH separately as well as consecutively under relative mild conditions (120°C, 1h). Pretreatment with 5% H2SO4 or 5% HCl solubilized 85% of the hemicellulose fraction, but the enzymatic conversion of pretreated materials increased only
two times compared to the untreated corn stover. Applying acidic pretreatment following a 1-d soaking in base achieved enzymatic
conversion that was nearly the theoretical maximum (95.7%). Pretreatment with 10% NaOH decreased the lignin fraction >95%,
increased the enzymatic conversion more than four times, and gave a 79.4% enzymatic conversion. However, by increasing the
reaction time, the enzymatic degradability could also be increased significantly, using a less concentrated base. When the
time of pretreatment was increased three times (0.5% NaOH at 120°C), the amount of total released sugars was 47.9 g from 100
g (dry matter) of untreated corn stover. 相似文献
15.
Luisa Maurelli Elena Ionata Francesco La Cara Alessandra Morana 《Applied biochemistry and biotechnology》2013,170(5):1104-1118
Chestnut shell (CS) is an agronomic residue mainly used for extraction of antioxidants or as adsorbent of metal ions. It also contains some polysaccharide that has not been considered as potential source of fermentable sugars for biofuel production until now. In this study, the effect of different pretreatment methods on CS was evaluated in order to obtain the greatest conversion of cellulose and xylan into fermentable sugars. Hot acid impregnation, steam explosion (acid-catalysed or not), and aqueous ammonia soaking (AAS) were selected as pretreatments. The pretreated biomass was subjected to saccharification with two enzyme cocktails prepared from commercial preparations, and evaluation of the best pretreatment and enzyme cocktail was based on the yield of fermentable sugars produced. As AAS provided the best result after preliminary experiments, enhancement of sugar production was attempted by changing the concentrations of ammonium hydroxide, enzymes, and CS. The optimal pretreatment condition was 10 % ammonium hydroxide, 70 °C, 22 h with CS at 5 % solid loading. After saccharification of the pretreated CS for 72 h at 50 °C and pH 5.0 with a cocktail containing cellulase (Accellerase 1500), beta-glucosidase (Accellerase BG), and xylanase (Accellerase XY), glucose and xylose yields were 67.8 and 92.7 %, respectively. 相似文献
16.
Mônica Caramez Triches Damaso Aline Machado de Castro Raquel Machado Castro Carolina Maria M. C. Andrade Nei Pereira Jr. 《Applied biochemistry and biotechnology》2004,115(1-3):1003-1012
Xylanases have significant current and potential uses for several industries including paper and pulp, food, and biofuel.
For the biofuel industry, xylanases can be used to aid in the conversion of lignocellulose to fermentable sugars (e.g., xylose).
We investigated the thermophilic fungus Thermomyces lanuginosus was yielded for xylanase production and found that the highest activity (850 U/mL) was yielded after 96 h of semisolid fermentation.
The enzyme was used for hydrolyzing agricultural residues with and without pretreatment. Such residues were characterized
in relation to the maximum xylose content by total acid hydrolysis. The highest xylose yields realized by enzymatic hydrolysis
were 24 and 52%, achieved by using 3000 U/g (dried material) of sugarcane bagasse and corncob, respectively, which received
both alkali and thermal pretreatment. 相似文献
17.
Wang Lin Dale Bruce E. Yurttas Lale Goldwasser I. 《Applied biochemistry and biotechnology》1998,(1):51-66
Process designs were conducted for each unit of the conceptual ammonia fiber explosion (AFEX) process, and fixed capital investment
and operating costs were estimated. AFEX costs about $20-40/t of dry bio-mass treated. Several promising areas for reducing
process costs exist. Return on investment (ROI) calculations were also done for AFEX-treated materials (as digestibility-enhanced
animal feeds), in conjunction with sensitivity analyses on the overall processing costs. Estimated ROIs range from over 100%/y
to negative, depending on the system variables. The most important variables are the cost of corn and corn fiber, ammonia
loading, and whether or not drying is required. 相似文献
18.
Bradshaw TC Alizadeh H Teymouri F Balan V Dale BE 《Applied biochemistry and biotechnology》2007,137(1-12):395-405
Plant materials from the vegetative growth stage of reed canarygrass and the seed stage of reed canarygrass are pretreated by ammonia fiber expansion (AFEX) and enzymatically hydrolyzed using 15 filter paper units (FPU) cellulase/g glucan to evaluate glucose and xylose yields. Percent conversions of glucose and xylose, effects of temperature and ammonia loading, and hydrolysis profiles are analyzed to determine the most effective AFEX treatment condition for each of the selected materials. The controls used in this study were untreated samples of each biomass material. All pretreatment conditions tested enhanced enzyme digestibility and improved sugar conversions for reed canarygrass compared with their untreated counterparts. Based on 168 h hydrolysis results using 15 FPU Spezyme CP cellulase/g glucan the most effective AFEX treatment conditions were determined as: vegetative growth stage of reed canarygrass--100 degrees C, 60% moisture content, 1.2:1 kg ammonia/kg of dry matter (86% glucose and 78% xylose) and seed stage of reed canarygrass--100 degrees C, 60% moisture content, 0.8:1 kg ammonia/kg of dry matter (89% glucose and 81% xylose). Supplementation by commercial Multifect 720 xylanase along with cellulase further increased both glucose and xylose yields by 10-12% at the most effective AFEX conditions. 相似文献
19.
Ballesteros M José Negro M Manzanares P Ballesteros I Sáez F Oliva JM 《Applied biochemistry and biotechnology》2007,137(1-12):239-252
Cynara cardunculus L. (cardoon) is a Mediterranean perennial herb offering good potential as substrate for sustainable production of bioethanol. In this work the first approach to the study of dilute-acid pretreatment of cardoon biomass for biological conversion was made. The influence of temperature (160-200 degrees C), acid concentration (0-0.2% [w/w]), and solid concentration (5-10% [w/v]) in the formation of free sugars and sugar decomposition products in the prehydrolyzate was studied using a response surface methodology. Results show a negative interaction effect between acid concentration and temperature in xylose recovery yield in prehydrolyzate, whereas dry matter concentration does not exert a significant effect. Xylose recovery yield reaches a maximum of about 80% of the content in dry untreated raw material at 180 degrees C and 0.1 or 0.2% acid addition. At these conditions the ratio of monomers found in prehydrolyzate in relation to total sugar yield for xylose is close to 100%. Furfural concentration, the major furan determined in the prehydrolyzate, increases as pretreatment severity rises. Maximum furfural yield of 4.2 g/100 g dry untreated raw material was found at 200 degrees C and 0.2% acid concentration. The yield of furfural at the conditions in which maximum xylose recovery is attained is substantially lower, less than 2 g/100 g dry untreated raw material. This fact supports the idea of using moderate temperatures in dilute-acid processes, which at the same time provides reasonably high sugar recovery yield and avoids high inhibitory products formation. 相似文献
20.
Vijay Sundaram Kasiviswanathan Muthukumarappan Stephen Gent 《Applied biochemistry and biotechnology》2017,181(3):1060-1079
Lignocellulosic feedstocks corn stover, prairie cord grass, and switchgrass were subjected to ammonia fiber expansion (AFEX?) pretreatment and densified using extrusion pelleting and ComPAKco densification technique. The effects of AFEX? pretreatment and densification were studied on the fast pyrolysis product yields. Feedstocks were milled in a hammer mill using three different screen sizes (2, 4, and 8 mm) and were subjected to AFEX? pretreatment. The untreated and AFEX?-pretreated feedstocks were moisture adjusted at three levels (5, 10, and 15 % wb) and were extruded using a lab-scale single screw extruder. The barrel temperature of the extruder was maintained at 75, 100, and 125 °C. Durability of the extruded pellets made from AFEX?-pretreated corn stover, prairie cord grass, and switchgrass varied from 94.5 to 99.2, 94.3 to 98.7, and 90.1 to 97.5 %, respectively. Results of the thermogravimetric analysis showed the decrease in the decomposition temperature of the all the feedstocks after AFEX? pretreatment indicating the increase in thermal stability. Loose and densified feedstocks were subjected to fast pyrolysis in a lab-scale reactor, and the yields (bio-oil and bio-char) were measured. Bio-char obtained from the AFEX?-pretreated feedstocks exhibited increased bulk and particle density compared to the untreated feedstocks. The properties of the bio-oil were statistically similar for the untreated, AFEX?-pretreated, and AFEX?-pretreated densified feedstocks. Based on the bio-char and bio-oil yields, the AFEX?-pretreated feedstocks and the densified AFEX?-pretreated feedstocks (pellets and PAKs) exhibited similar behavior. Hence, it can be concluded that densifying the AFEX?-pretreated feedstocks could be a viable option in the biomass-processing depots to reduce the transportation costs and the logistical impediments without affecting the product yields. 相似文献