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1.
Hou-Rui Z Xiang-Xiang Q Silva SS Sarrouh BF Ai-Hua C Yu-Heng Z Ke J Qiu X 《Applied biochemistry and biotechnology》2009,152(2):199-212
In this paper, two new strians, Issatchenkia occidentalis (Lj-3, CCTCC M 2006097) and Issatchenkia orienalis (S-7, CCTCC M 2006098), isolated from different environments on solid media, were used in the detoxification process of the
hemicellulosic hydrolysate of sugarcane bagasse. High-pressure liquid chromatography elution curve of UV-absorption compounds
represented by acetic acid, furfural, and guaiacol (toxic compounds found in the hemicellulosic hydrolysate) showed that several
chromatographic peaks were evidently diminished for the case of detoxified hydrolysate with isolate strains compared to the
high peaks resulted for no detoxified hydrolysate. It was clear that these inhibitors were degraded by the two new isolates
during their cultivation process. Fermentation results for the biodetoxified hydrolysate showed an increase in xylitol productivity
(Q
p) by 1.97 and 1.95 times (2.03 and 2.01 g l−1 h−1) and in xylitol yield (Y
p) by 1.72 and 1.65 times (0.93 and 0.89 g xylitol per gram xylose) for hydrolysate treated with S-7 and Lj-3, respectively,
in comparison with no detoxified hydrolysate (1.03 g l−1 h−1 and 0.54 g xylitol per gram xylose). This present work demonstrated the importance of Issatchenkia yeast in providing an effective biological detoxification approach to remove inhibitors and improve hydrolysate fermentability,
leading to a high xylitol productivity and yield. 相似文献
2.
Luís C. Duarte Florbela Carvalheiro Sónia Lopes Susana Marques Juan Carlos Parajo Francisco M. Gírio 《Applied biochemistry and biotechnology》2004,115(1-3):1041-1058
A readily fermentable pentose-containing hydrolysate was obtained from Brewery's spent grain by a two-step process consisting
of an auto-hydrolysis (converting the hemicelluloses into oligosaccharides) followed by an enzymatic or sulfuric acid-catalyzed
posthydrolysis (converting the oligosaccharides into monosaccharides). Enzymatic hydrolyses were performed with several commercial
enzymes with xylanolytic and cellulolytic activities. Acid-catalyzed hydrolyses were carried out at 121°C under various sulfuric
acid concentrations and reaction times, and the effects of treatments were interpreted by means of a corrected combined severity
factor (CS
1), which varied in the range of 0.80–2.01. Under the tested conditions, chemicalhydrolysis allowed higher pentose yields than
enzymatic hydrolysis. Optimized conditions (defined by CS
1=1.10) allowed both complete monosaccharide recovery and low content of inhibitors. Liquors subjected to posthydrolysis under
optimal conditions were easily fermented by Debaryomyces hansenii CCMI 941 in semiaerobic shake-flask experiments, leading to xylitol and arabitol as major fermentation products. The bioconversion
process was improved by hydrolysate concentration and supplementation of fermentation media with casamino acids.
The authors wish it to be known that the first two authors should be regarded as joint First Authors. 相似文献
3.
Soybean hulls were subjected to thermo-mechanical extrusion pretreatment at various in-barrel moisture contents and screw
speeds. Extrusion degraded the lignocellulosic structure and enhanced enzymatic hydrolysis of soybean hulls, with up to 155%
increase in glucose yield as compared to untreated substrate. Greater glucose yields were observed at higher in-barrel moistures
(45% and 50%) and lower screw speed (280 and 350 rpm). Maximum 74% cellulose to glucose conversion resulted from using a two-enzyme
cocktail consisting of cellulase and β-glucosidase. Conversion increased to 87% when a three-enzyme cocktail having a cell
wall degrading enzyme complex was used for hydrolysis. Fermentation inhibitors, such as furfural, 5-(hydroxymethyl)-2-furaldehyde
(HMF), and acetic acid, were found in the extrusion pretreated soybean hulls and hydrolysate. However, their concentrations
were below the known thresholds for inhibition. Fermentation of hydrolysate by Saccharomyces cerevisiae led to high yields of ethanol, with concentration ranging from 13.04 to 15.44 g/L. 相似文献
4.
Treatment with lignin residue 总被引:1,自引:0,他引:1
Björklund Linda Larsson Simona Jönsson Leif J. Reimann Anders Nivebrant Nils-Olof 《Applied biochemistry and biotechnology》2002,98(1-9):563-575
Acid hydrolysis of lignocellulose to hydrolysates intended for production of fuel ethanol results in the formation of byproducts
in addition to fermentable sugars. Some of the byproducts, such as phenolic compounds and furan aldehydes, are inhibitory
to the fermenting microorganism. Detoxification of the hydrolysates may be necessary for production of ethanol at a satisfactory
rate and yield. The lignin residue obtained after hydrolysis is a material with hydrophobic properties that is produced in
large amounts as a byproduct within an ethanol production process based on lignocellulosic raw materials. We have explored
the possibility of using this lignin residue for detoxification of spruce dilute-acid hydrolysates prior to fermentation with
Saccharomyces cerevisiae. Three dilute-acid hydrolysates of spruce were treated with lignin residue, which in all cases resulted in improved fermentability
in terms of productivity and yield of ethanol. The effect was improved by washing the lignin before treatment, by using larger
amounts of lignin in the treatment, and by performing the treatment at low temperature. Treatment with the lignin residue
removed up to 53% of the phenolic compounds and up to 68% of the furan aldehydes in a spruce dilute-acid hydrolysate. A larger
fraction of furfural was removed compared to the less hydrophobic 5-hydroxymethylfurfural. 相似文献
5.
Luís C. Duarte Florbela Carvalheiro Joana Tadeu Francisco M. Gírio 《Applied biochemistry and biotechnology》2006,130(1-3):461-475
The combined effects of inhibitors present in lignocellulosic hydrolysates was studied using a multivariate statistical approach.
Acetic acid (0–6 g/L), formic acid (0–4.6 g/L) and hydroquinone (0–3 g/L) were tested as model inhibitors in synthetic media
containing a mixture of glucose, xylose, and arabinose simulating concentrated hemicellulosic hydrolysates. Inhibitors were
consumed sequentially (acetic acid, formic acid, and hydroquinone), alongside to the monosaccharides (glucose, xylose, and
arabinose). Xylitol was always the main metabolic product. Additionally, glycerol, ethanol, and arabitol were also obtained.
The inhibitory action of acetic acid on growth, on glucose consumption and on all product formation rates was found to be
significant (p≤0.05), as well as formic acid inhibition on xylose consumption and biomass production. Hydroquinone negatively affected biomass
productivity and yield, but it significantly increased xylose consumption and xylitol productivity. Hydroquinone interactions,
either with acetic or formic acid or with both, are also statistically signficant. Hydroquinone seems to partially lessen
the acetic acid and amplify formic acid effects. The results clearly indicate that the interaction effects play an important
role on the xylitol bioprocess. 相似文献
6.
Tammy Kay Hayward Jenny Hamilton David Templeton Ed Jennings Mark Ruth Arun Tholudur James D. McMillan Mel Tucker Ali Mohagheghi 《Applied biochemistry and biotechnology》1999,77(1-3):293-309
National Renewable Energy Laboratory (NREL) has developed a conditioning process that decreases acetic acid levels in pretreated
yellow poplar hydrolysate. Trichoderma reesei is sensitive to acetic acid and this conditioning method has enabled applied cellulase production with hardwoods. T. reesei strains QM9414, L-27, RL-P37, and Rut C-30 were screened for growth on conditioned hydrolysate liquor. Tolerance to hydrolysate
was found to be strain-dependent. Strain QM9414 was adapted to grow in 80% (v/v) conditioned hydrolysate (40 g/L of soluble
sugars and 1.6 g/L acetic acid from pretreated poplar). However, enzyme production was highest at 20% (v/v) hydrolysateusing
strain L-27. Cellulasetiters of 2–3 International Filter Paper Units (IFPU)/mL were achieved using pretreated yellow poplar
liquors and solids as the sole carbon sources. 相似文献
7.
Six anion-exchange resins with different properties were compared with respect to detoxification of a dilute-acid hydrolysate
of spruce prior to ethanolic fermentation with Saccharomyces cerevisiae. The six resins encompassed strong and weak functional groups as well as styrene-, phenol-, and acrylic-based matrices. In
an analytical experimental series, fractions from columns packed with the different resins were analyzed regarding pH, glucose,
furfural, hydroxymethylfurfural, phenolic compounds, levulinic acid, acetic acid, formic acid, and sulfate. An initial adsorption
of glucose occurred in the strong alkaline environment and led to glucose accumulation at a later stage. Acetic and levulinic
acid passed through the column before formic acid, whereas sulfate had the strongest affinity. In a preparative experimental
series, one fraction from each of six columns packed with the different resins was collected for assay of the fermentability
and analysis of glucose, mannose, and fermentation inhibitors. The fractions collected from strong anion-exchange resins with
styrene-based matrices displayed the best fermentability: a sevenfold enhancement of ethanol productivity compared with untreated
hydrolysate. Fractions from a strong anion exchanger with acrylic-based matrix and a weak exchanger with phenol-based resin
displayed an intermediate improvement in fermentability, a four- to fivefold increase in ethanol productivity. The fractions
from two weak exchangers with styrene- and acrylic-based matrices displayed a twofold increase in ethanol productivity. Phenolic
compounds were more efficiently removed by resins with styrene-and phenol-based matrices than by resins with acrylic-based
matrices. 相似文献
8.
Martín Carlos Galbe Mats Nilvebrant Nils-Olof Jönsson Leif J. 《Applied biochemistry and biotechnology》2002,98(1-9):699-716
Sugarcane bagasse is a potential lignocellulosic feedstock for ethanol production, since it is cheap, readily available, and
has a high carbohydrate content. In this work, bagasse was subjected to steam explosion pretreatment with different impregnation
conditions. Three parallel pretreatments were carried out, one without any impregnation, a second with sulfur dioxide, and
a third with sulfuric acid as the impregnating agent. The pretreatments were performed at 205°C for 10 min. The pretreated
material was then hydrolyzed using celluloytic enzymes. The chemical composition of the hydrolyzates was analyzed. The highest
yields of xylose (16.2 g/100 g dry bagasse), arabinose (1.5 g/100 g), and total sugar (52.9 g/100 g) were obtained in the
hydrolysis of the SO2-impregnated bagasse. The H2SO4-impregnated bagasse gave the highest glucose yield (35.9 g/100 g) but the lowest total sugar yield (42.3 g/100 g) among the
three methods. The low total sugar yield from the H2SO4-impregnated bagasse was largely due to by-product formation, as the dehydration of xylose to furfural. Sulfuric acid impregnation
led to a three-fold increase in the concentration of the fermentation inhibitors furfural and 5-hydroxymethylfurfural (HMF)
and a two-fold increase in the concentration of inhibitory aliphatic acids (formic, acetic, and levulinic acids) compared
to the other two pretreatment methods. The total content of phenolic compounds was not strongly affected by the different
pretreatment methods, but the quantities of separate phenolic compounds were widely different in the hydrolyzate from the
H2SO4-impregnated bagasse compared with the other two hydrolyzates. No major differences in the content of inhibitors were observed
in the hydrolyzates obtained from SO2-impregnated and non-impregnated bagasse. The fermentability of all three hydrolyzates was tested with a xylose-utilizing
Saccharomyces cerevisiae strain with and without nutrient supplementation. The hydrolyzates of SO2-impregnated and nonimpregnated bagasse showed similar fermentability, whereas the hydrolyzate of H2SO4-impregnated bagasse fermented considerably poorer. 相似文献
9.
The production cost of cellulolytic enzymes is a major contributor to the high cost of ethanol production from lignocellulosics
using enzymatic hydrolysis. The aim of the present study was to investigate the cellulolytic enzyme production ofTrichoderma reesei Rut C 30, which is known as a good cellulase secreting micro-organism, using willow as the carbon source. The willow, which
is a fast-growing energy crop in Sweden, was impregnated with 1–4% SO2 and steam-pretreated for 5 min at 206°C. The pretreated willow was washed and the wash water, which contains several soluble
sugars from the hemicellulose, was supplemented with fibrous pretreated willow and used for enzyme production. In addition
to sugars, the liquid contains degradation products such as acetic acid, furfural, and 5-hydroxy-methylfurfural, which are
inhibitory for microorganisms. The results showed that 50% of the cellulose can be replaced with sugars from the wash water.
The highest enzyme activity, 1.79 FPU/mL and yield, 133 FPU/g carbohydrate, was obtained at pH 6.0 using 20 g/L carbon source
concentration. At lower pHs, a total lack of growth and enzyme production was observed, which probably could be explained
by furfural inhibition. 相似文献
10.
Effect of acetic acid and furfural on cellulase production of Trichoderma reesei RUT C30 总被引:4,自引:0,他引:4
Because of the high temperature applied in the steam pretreatment of lignocellulosic materials, different types of inhibiting
degradation products of saccharides and lignin, such as acetic acid and furfural, are formed. The main objective of the present
study was to examine the effect of acetic acid and furfural on the cellulase production of a filamentous fungus Trichoderma reesei RUT C30, which is known to be one of the best cellulase-producing strains. Mandels’s mineral medium, supplemented with steam-pretreated
willow as the carbon source at a concentration corresponding to 10 g/L of carbohydrate, was used. Four different concentration
levels of acetic acid (0–3.0 g/L) and furfural (0–1.2 g/L) were applied alone as well as in certain combinations. Two enzyme
activities, cellulase and β-glucosidase, were measured. The highest cellulase activity obtained after a 7-d incubation was
1.55 FPU/mL with 1.0 g/L of acetic acid and 0.8 g/L of furfural added to the medium. This was 17% higher than that obtained
without acetic acid and furfural. Furthermore, the results showed that acetic acid alone did not influence the cellulase activity
even at the highest concentration. However, β-glucosidase activity was increased with increasing acetic acid concentration.
Furfural proved to be an inhibiting agent causing a significant decrease in both cellulase and β-glucosidase production. 相似文献
11.
Steam-exploded corn stover biomass was used as the substrate for fed-batch separate enzymatic hydrolysis and fermentation
(SHF) to investigate the solid concentration ranging from 10% to 30% (w/w) on the lignocellulose enzymatic hydrolysis and fermentation. The treatment of washing the steam-exploded material was also
evaluated by experiments. The results showed that cellulose conversion changed little with increasing solid concentration,
and fermentation by Saccharomyces cerevisiae revealed a nearly same ethanol yield with the water-washed steam-exploded corn stover. For the washed material at 30% substrate
concentration, i.e., 30% water insoluble solids (WIS), enzymatic hydrolysis yielded 103.3 g/l glucose solution and a cellulose
conversion of 72.5%, thus a high ethanol level up to 49.5 g/l. With the unwashed steam-exploded corn stover, though a cellulose
conversion of 70.9% was obtained in hydrolysis at 30% solid concentration (27.9% WIS), its hydrolysate did not ferment at
all, and the hydrolysate of 20% solid loading containing 3.3 g/l acetic acid and 145 mg/l furfural already exerted a strong
inhibition on the fermentation and ethanol production. 相似文献
12.
Alves Lourdes A. Vitolo Michele Felipe Maria das Graças A. de Almeida e Silva João Batista 《Applied biochemistry and biotechnology》2002,98(1-9):403-413
The sugarcane bagasse hydrolysate, which is rich in xylose, can be used as culture medium for Candida guilliermondii in xylitol production. However, the hydrolysate obtained from bagasse by acid hydrolysis at 120°C for 20 min has by-products
(acetic acid and furfural, among others), which are toxic to the yeast over certain concentrations. So, the hydrolysate must
be pretreated before using in fermentation. The pretreatment variables considered were: adsorption time (15,37.5, and 60 min),
type of acid used (H2So4 and H3Po4), hydrolysate concentration (original, twofold, and fourfold. concentrated), and active
charcoal (0.5, 1.75 and 3.0%). The suitability of the pretreatment was followed by measuring the xylose reductase (XR) and
xylitol dehydrogenase (XD) activity of yeast grown in each treated hydrolysate. The response surface methodology (24 full factorial design with a centered face) indicated that the hydrolysate might be concentrated fourfold and the pH adjusted
to 7.0 with CaO, followed by reduction to 5.5 with H3PO4. After that it was treated with active charcoal (3.0%) by 60 min. This pretreated hydrolysate attained the high XR/XD ratio
of 4.5. 相似文献
13.
Effects of sugar inhibition on cellulases and β-glucosidase during enzymatic hydrolysis of softwood substrates 总被引:1,自引:0,他引:1
Zhizhuang Xiao Xiao Zhang David J. Gregg John N. Saddler 《Applied biochemistry and biotechnology》2004,115(1-3):1115-1126
A quantitative approach was taken to determine the inhibition effects of glucose and other sugar monomers during cellulase
and β-Glucosidase hydrolysis of two types of cellulosic material: Avicel and acetic acid-pretreated softwood. The increased
glucose content in the hydrolysate resulted in a dramatic increase in the degrees of inhibition on both β-Glucosidase and
cellulase activities. Supplementation of mannose, xylose, and galactose during cellobiose hydrolysis did not show any inhibitory
effects on β-Glucosidase activity. However, these sugars were shown to have significant inhibitory effects on cellulase activity
during cellulose hydrolysis. Our study suggests that high-substrate consistency hydrolysis with supplementation of hemicellulose
is likely to be a practical solution to minimizing end-product inhibition effects while producing hydrolysate with high glucose
concentration. 相似文献
14.
Determination of the hydrothermal degradation products of D-(U-14C) glucose and D-(U-14C) fructose by TLC 总被引:1,自引:0,他引:1
The hydrothermal degradation was examined using D-(U-14C) glucose and D-(U-14C) fructose. By thin layer chromatography with methylene chloride, tetrahydrofuran (THF), acetic acid −60∶20∶20 as a mobile
phase it was, possible to separate and identify the carbohydrates and their reaction products, glyceraldehyde, dihydroxyacetone,
methylglyoxal, glycolaldehyde, 5-hydroxymethylfurfural and furfural. Up to 99% of the initial activity was determined by scintillation
counting of the TL-chromatograms. A reaction scheme for the hydrothermal degradation of glucose and fructose was obtained
from these results. 相似文献
15.
Iogen (Canada) is a major manufacturer of industrial cellulase and hemicellulase enzymes for the textile, pulp and paper, and poultry feed industries. Iogen has recently constructed a 40 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. The integration of enzyme and ethanol plants results in significant reduction in production costs and offers an alternative use for the sugars generated during biomass conversion. Iogen has partnered with the University of Toronto to test the fermentation performance characteristics of metabolically engineered Zymomonas mobilis created at the National Renewable Energy Laboratory. This study focused on strain AX101, a xylose- and arabinose-fermenting stable genomic integrant that lacks the selection marker gene for antibiotic resistance. The “Iogen Process” for biomass depolymerization consists of a dilute-sulpfuric acid-catalyzed steam explosion, followed by enzymatic hydrolysis. This work examined two process design options for fermentation, first, continuous cofermentation of C5 and C6 sugars by Zm AX101, and second, separate continuous fermentations of prehydrolysate by Zm AX101 and cellulose hydrolysate by either wildtype Z. mobilis ZM4 or an industrial yeast commonly used in the production of fuel ethanol from corn. Iogen uses a proprietary process for conditioning the prehydrolysate to reduce the level of inhibitory acetic acid to at least 2.5 g/L. The pH was controlled at 5.5 and 5.0 for Zymomonas and yeast fermentations, respectively. Neither 2.5 g/L of acetic acid nor the presence of pentose sugars (C6:C5 = 2:1) appreciably affected the high-performance glucose fermentation of wild-type Z. mobilis ZM4. By contrast, 2.5 g/L of acetic acid significantly reduced the rate of pentose fermentation by strain AX101. For single-stage continuous fermentation of pure sugar synthetic cellulose hydrolysate (60 g/L of glucose), wild-type Zymomonas exhibited a four-fold higher volumetric productivity compared with industrial yeast. Low levels of acetic acid stimulated yeast ethanol productivity. The glucose-to-ethanol conversion efficiency for Zm and yeast was 96 and 84%, respectively. 相似文献
16.
Takahashi CM Takahashi DF Carvalhal ML Alterthum F 《Applied biochemistry and biotechnology》1999,80(3):193-203
Escherichia coli KO11, in which the genes pdc (pyruvate decarboxylase) and adh (alcohol dehydrogenase) encoding the ethanolpathway from Zymomonas mobili were inserted into the chromosome, has been shown to metabolize all major sugars that are consituents of hemicellulosic hydrolysates
to ethanol, in anaerobic conditions. However, the growth and fermentation performance of this recombinant bacteria may be
affected by acetic acid a potential inhibitor present in hemicellulose hydrolysates in a range of 2.0–15.0 g/L. It was observed
that acetate affected the growth of E. coli KO11, prolonging the lag phase and inducing loss of biomass production and reduction of growth rate. At lower pH levels,
the sensitivity to acetic acid was enhanced owing to the increased concentration of the protonated species. On the other hand,
the recombinant bacteria showed a high tolerance to acetic acid regarding fermentative performance. In Luria broth medium
with glucose or xylose as a single sugar source, it was observed that neither yield nor productivity was affected by the addition
of acetate in a range of 2.0–12.0 g/L, suggesting some uncoupling of the growth vs ethanol production. 相似文献
17.
Nils-Olof Nilvebrant Per Persson Anders Reimann Filipe de Sousa Lo Gorton Leif J. Jönsson 《Applied biochemistry and biotechnology》2003,107(1-3):615-628
In addition to fermentable sugars, dilute-acid hydrolysates of lignocellulose contain compounds that inhibit fermenting microorganisms,
such as Saccharomyces cerevisiae. Previous results show that phenolic compounds and furan aldehydes, and to some extent aliphatic acids, act as inhibitors
during fermentation of dilute-acid hydrolysates of spruce. Treatment of lignocellulose hydrolysates with alkali, usually in
the form of overliming to pH 10.0, has been frequently employed as a detoxification method to improve fermentability. A spruce
dilute-acid hydrolysate was treated with NaOH in a factorial design experiment, in which the pH was varied between 9.0 and
12.0, the temperature between 5 and 80°C, and the time between 1 and 7 h. Already at pH 9.0, >25% of the glucose was lost
when the hydrolysate was treated at 80°C for 1 h. Among the monosaccharides, xylose was degraded faster under alkaline conditions
than the hexoses (glucose, mannose, and galactose), which, in turn, were degraded faster than arabinose. The results suggest
that alkali treatment of hydrolysates can be performed at temperatures below 30°C at any pH between 9.0 and 12.0 without problems
with sugar degradation or formation of inhibiting aliphatic acids. Treatment with Ca(OH)2 instead of NaOH resulted in more substantial degradation of sugars. Under the harsher conditions of the factorial design
experiment, the concentrations of furfural and 5-hydroxymethylfurfural decreased while the total phenolic content increased.
The latter phenomenon was tentatively attributed to fragmentation of soluble aromatic oligomers in the hydrolysate. Separate
phenolic compounds were affected in different ways by the alkaline conditions with some compounds showing an increase in concentration
while others decreased. In conclusion, the conditions used for detoxification with alkali should be carefully controlled to
optimize the positive effects and minimize the degradation of fermentable sugars. 相似文献
18.
Dilute acid hydrolysate of corn fiber was used as carbon source for the production of succinic acid by Actinobacillus succinogenes NJ113. The optimized hydrolysis conditions were obtained by orthogonal experiments. When corn fiber particles were of 20
mesh in size and treated with 1.0% sulfuric acid at 121 °C for 2 h, the total sugar yield could reach 63.3%. It was found
that CaCO3 neutralization combined with activated carbon adsorption was an effective method to remove fermentation inhibitors especially
furfural that presented in the acid hydrolysate of corn fiber. Only 5.2% of the total sugar was lost, while 91.9% of furfural
was removed. The yield of succinic acid was higher than 72.0% with the detoxified corn fiber hydrolysate as the carbon source
in anaerobic bottles or 7.5 L fermentor cultures. It was proved that the corn fiber hydrolysate could be an alternative to
glucose for the production of succinic acid by A. succinogenes NJ113. 相似文献
19.
A simple and effective high-performance liquid chromatographic (HPLC) method has been developed for simultaneous quantification
of three phenolic acids (3,4-dihydroxyphenyllactic acid (Chinese name danshensu), protocatechuic aldehyde, and salvianolic
acid B) and four diterpenes (dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA) in radix salviae miltiorrhizae. Chromatography was performed on a 250 mm × 4.6 mm i.d., 5-μm particle size, C18 column. The mobile phase was a linear gradient prepared from 0.1% (v/v) aqueous formic acid and acetonitrile at a flow-rate of 1.0 mL min−1. All the target components were well separated with high resolution and without interference. Good linearity (R
2 > 0.999) was observed over the concentration ranges investigated, and intra-day and inter-day precision were high. Temperature-controlled
ultrasound-assisted extraction was used to prevent hydrolysis of thermally unstable components during the sample-extraction
procedure, and the extraction conditions were carefully optimized. Recovery of the seven components was from 98.45 to 100.63%
and relative standard deviations were always <1.5%. The validated method was successfully used for simultaneous quantification
of the three phenolic acids and the four diterpenes in radix salviae miltiorrhizae of different geographic origins. 相似文献
20.
Nilvebrant Nils-Olof Reimann Anders Larsson Simona Jönsson Leif J. 《Applied biochemistry and biotechnology》2001,91(1-9):35-49
Lignocellulose hydrolysates contain fermentation inhibitors causing decreased ethanol production. The inhibitors include phenolic
compounds, furan aldehydes, and aliphatic acids. One of the most efficient methods for removing inhibiting compounds prior
to fermentation is treatment of the hydrolysate with ion-exchange resins. The performance and detoxification mechanism of
three different resins were examined: an anion exchanger, a cation exchanger, and a resin without charged groups (XAD8). A
dilute acid hydrolysate of spruce was treated with the resins at pH 5.5 and 10.0 prior to ethanolic fermentation with Saccharomyces cerevisiae. In addition to the experiments with hydrolysate, the effect of the resins on selected model compounds, three phenolics (vanillin,
guaiacol, and coniferyl aldehyde) and two furan aldehydes (furfural and hydroxymethyl furfural), was determined. The cation
exchanger increased ethanol production, but to a lesser extent than XAD-8, which in turn was less effective than the an ion
exchanger. Treatment at pH 10.0 was more effective than at pH 5.5. At pH 10.0, the anion exchanger efficiently removed both
anionic and uncharged inhibitors, the latter by hydrophobic interactions. The importance of hydrophobic interactions was further
indicated by a substantial decrease in the concentration of model compounds, such as guaiacol and furfural, after treatment
with XAD-8. 相似文献