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1.
Fábio C. Sampaio Paolo Torre Flávia M. Lopes Passos Célia Alencar de Moraes Patrizia Perego Attilio Converti 《Applied biochemistry and biotechnology》2007,136(2):165-181
To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic
hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3–6.5 g/L), xylose
(60.1–92.1 g/L), or arabinose (5.9–9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical
inhibitors of acidic hydrolysates, such as furfural (1.0–5.0 g/L), hydroxymethylfurfural (0.01–0.30 g/L), acetic acid (0.5–3.0
g/L), and vanillin (0.5–3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation
media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization
was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The
results suggest potential application of this strain in xyloseto-xylitol bioconversion from complex xylose media from lignocellulosic
materials. 相似文献
2.
Sugar cane bagasse was hydrolyzed under different concentrations of hydrochloric acid (2–6%), reaction times (0–300 min),
and temperatures (100–128°C). Sugars obtained (xylose, glucose, arabinose, and glucose) and deg-radation products (furfural
and acetic acid) were determined. Based on the Saeman model and the two-fraction model, kinetic parameters for predicting
these compounds in the hydrolysates were developed. The influence of temperature was studied using the Arrhenius equation.
The optimal conditions selected were 128°C, 2% HCl, and 51.1 min. Using these conditions, 22.6g xylose/L, 3.31 garabinose/L,
3.77 g glucose/L, 3.59 g acetic acid/L, and 1.54 g furfural/L were obtained. 相似文献
3.
Luís C. Duarte Florbela Carvalheiro Inês Neves Francisco M. Gírio 《Applied biochemistry and biotechnology》2005,121(1-3):413-425
Debaryomyces hansenii is a polyol overproducing yeast that can have a potential use for upgrading lignocellulosic hydrolysates. Therefore, the establishment of its tolerance to metabolic inhibitors found in hydrolysates is of major interest. We studied the effects of selected aliphatic acids, phenolic compounds, and furfural. Acetic acid favored biomass production for concentrations <6.0 g/L. Formic acid was more toxic than acetic acid and induced xylitol accumulation (maximum yield of 0.21 g/g of xylose). All tested phenolics strongly decreased the specific growth rate. Increased toxicity was found for hydroquinone, syringaldehyde, and 4-methylcatechol and was correlated to the compound’s hydrophobicity. Increasing the amount of furfural led to longer lag phases and had a detrimental effect on specific growth rate and biomass productivity. 相似文献
4.
Influence of inhibitory compounds and minor sugars on xylitol production by Debaryomyces hansenii 总被引:1,自引:0,他引:1
Sampaio FC Torre P Passos FM de Moraes CA Perego P Converti A 《Applied biochemistry and biotechnology》2007,136(2):165-182
To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3-6.5 g/L), xylose (60.1-92.1 g/L), or arabinose (5.9-9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical inhibitors of acidic hydrolysates, such as furfural (1.0-5.0 g/L), hydroxymethylfurfural (0.01- 0.30 g/L), acetic acid (0.5-3.0 g/L), and vanillin (0.5-3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The results suggest potential application of this strain in xyloseto- xylitol bioconversion from complex xylose media from lignocellulosic materials. 相似文献
5.
Florbela Carvalheiro Luís C. Duarte Raquel Medeiros Francisco M. Gírio 《Applied biochemistry and biotechnology》2004,115(1-3):1059-1072
Dilute-acid hydrolysis of brewery's spent grain to obtain a pentose-rich fermentable hydrolysate was investigated. The influence
of operational conditions on polysaccharide hydrolysis was assessed by the combined severity parameter (CS) in the range of 1.39–3.06. When the CS increased, the pentose sugars concentration increased to a maximum at a CS of 1.94, whereas the maximum glucose concentration was obtained for a CS of 2.65. The concentrations of furfural, hydroxymethylfurfural (HMF), as well as formic and levulinic acids and total phenolic
compounds increased with severity. Optimum hydrolysis conditions were found at a CS of 1.94 with >95% of feedstock pentose sugars recovered in the monomeric form, together with a low content of furfural, HMF,
acetic and formic acids, and total phenolic compounds. This hydrolysate containing glucose, xylose, and arabinose (ratio 10∶67∶32)
was further supplemented with inorganic salts and vitamins and readily fermented by the yeast Debaryomyces hansenii CCMI 941 without any previous detoxification stage. The yeast was able to consume all sugars furfural, HMF, and acetic acid
with high biomass yield, 0.68C-mol/C-mol, and productivity, 0.92 g/(L·h). Detoxification with activated charcoal resulted
in a similar biomass yield and a slight increase in the volumetric productivity (11%). 相似文献
6.
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
7.
Xylitol production by Debaryomyces hansenii NRRL Y-7426 was performed on synthetic medium varying the initial xylose concentration between 50 and 300 g/L. The experimental
results of these tests were used to investigate the effect of substrate level on xylose consumption by this yeast. Satisfactory
values of product yield on substrate (0.74–0.83 g/g) as well as volumetric productivity (0.481–0.694 g/L·h) were obtained
over a wide range of xylose levels (90–200 g/L), while a worsening of kinetic parameters took place at higher concentration,
likely due to a substrate inhibition phenomenon. The metabolic behavior of D. hansenii was studied, under these conditions, through a carbon material balance to estimate the fractions of xylose consumed by the
cell for different activities (xylitol production, biomass growth, and respiration) during the lag, exponential, and stationary
phases. 相似文献
8.
Walthers Thomas Hensirisak Patcharee Agblevor Foster A. 《Applied biochemistry and biotechnology》2001,91(1-9):423-435
The influence of other hemicellulosic sugars (arabinose, galactose, mannose, and glucose), oxygen limitation, and initial
xylose concentration on the fermentation of xylose to xylitol was in vestigated using experimental design methodology. Oxygen
limitation and initial xylose concentration had strong influences on xylitol production by Candida tropicalis ATCC 96745. Under semiaerobic conditions, xylitol yield was highest (0.62 g/g), whereas under aerobic conditions volumetric
productivity was highest (0.90g/[L·h]). In the presence of glucose, xylose utilization was strongly repressed and sequential
sugar utilization was observed. Ethanol produced from the glucose caused a 50% reduction in xylitol yield when the ethanol
con centration exceeded 30 g/L. When complex synthetic hemicellulosic sugars were fermented, glucose was initially consumed
followed by a simultaneous uptake of the other sugars. The highest xylitol yield (0.84 g/g) and volumetric productivity (0.49
g/[L·h]) were obtained for substrates containing high arabinose and low glucose and mannose contents. 相似文献
9.
Attilio Converti Patrizia Perego José Manuel Domínguez 《Applied biochemistry and biotechnology》1999,82(2):141-151
Three different yeasts, Pachysolen tannophilus, Debaryomyces hansenii, and Candida guilliermondii, were evaluated to ferment xylose solutions prepared from hardwood hemicellulose hydrolysates, among which P. tannophilus proved to be the most promising microorganism. However, the presence of both lignin-derived compounds (LDC) and acetic acid
rendered a poor fermentation. To enhance the fermentation kinetics, different treatments to purify the hydrolysates were studied,
including overliming, charcoal adsorption for LDC removal, and evaporation for acetic acid and furfural stripping. Under the
best operating conditions assayed, 39.5g/L of xylitol were achieved after 96 h of fermentation, which corresponds to a volumetric
productivity of 0.41 g/L·h and a yield of product on consumed substrate of 0.63 g
p
/gS. 相似文献
10.
Lawford Hugh G. Rousseau Joyce D. Tolan Jeffrey S. 《Applied biochemistry and biotechnology》2001,91(1-9):133-146
Iogen Corporation of Ottawa, Canada, has recently built a 50 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme
production facility. Iogen has partnered with the University of Toronto to test the C6/C5 cofermentation performance characteristics
of National Renewable Energy Laboratory's metabolically engineered Zymomonas mobilis using its biomass hydrolysates. In this study, the biomass feedstock was an agricultural waste, namely oat hulls, which was
hydrolyzed in a proprietary two-stage process involving pretreatment with dilute sulfuric acid at 200–250°C, followed by cellulase
hydrolysis. The oat hull hydrolysate (OHH) contained glucose, xylose, and arabinose in a mass ratio of about 8:3:0.5. Fermentation
media, prepared from diluted hydrolysate, were nutritionally amended with 2.5 mL/L of corn steep liquor (50% solids) and 1.2
g/L of diammonium phosphate. The estimated cost for large-scale ethanol production using this minimal level of nutrient supplementation
was 4.4c/gal of ethanol. This work examined the growth and fermentation performance of xyloseutilizing, tetracycline-resistant,
plasmid-bearing, patented, recombinant Z. mobilis cultures: CP4:pZB5, ZM4:pZB5, 39676:pZB4L, and a hardwood prehydrolysate-adapted variant of 39676:pZB4L (designated asthe
“adapted” strain). In pH-stat batch fermentations with unconditioned OHH containing 6% (w/v) glucose, 3% xylose, and 0.75%
acetic acid, rec Zm ZM4:pZB5 gave the best performance with a fermentation time of 30h, followed by CP4:pZB5 at 48h, with
corresponding volumetric productivities of 1.4 and 0.89 g/(L·h), respectively. Based on the available glucose and xylose,
the process ethanol yield for both strains was 0.47 g/g (92% conversion efficiency). At 48 h, the process yield for rec Zm
39676:pZB4L and the adapted strain was 0.32 and 0.34 g/g, respectively. None of the test strains was able to fermentarabinose.
Acetic acid tolerance appeared to be a major determining factor in cofermentation performance. 相似文献
11.
Glucose/xylose mixtures (90 g/L total sugar) were evaluated for their effect on ethanol fermentation by a recombinant flocculent Saccharomyces cerevisiae, MA-R4. Glucose was utilized faster than xylose at any ratio of glucose/xylose, although MA-R4 can simultaneously co-ferment both sugars. A high percentage of glucose can increase cell biomass production and therefore increase the rate of glucose utilization (1.224 g glucose/g biomass/h maximum) and ethanol formation (0.493 g ethanol/g biomass/h maximum). However, the best ratio of glucose/xylose for the highest xylose consumption rate (0.209 g xylose/g biomass/h) was 2:3. Ethanol concentration and yield increased and by-product (xylitol, glycerol, and acetic acid) concentration decreased as the proportion of glucose increased. The maximum ethanol concentration was 41.6 and 21.9 g/L after 72 h of fermentation with 90 g/L glucose and 90 g/L xylose, respectively, while the ethanol yield was 0.454 and 0.335 g/g in 90 g/L glucose and 90 g/L xylose media, respectively. High ethanol yield when a high percentage of glucose is available is likely due to decreased production of by-products, such as glycerol and acetic acid. These results suggest that ethanol selectivity is increased when a higher proportion of glucose is available and reduced when a higher proportion of xylose is available. 相似文献
12.
High-yield fermentation of pentoses into lactic acid 总被引:3,自引:0,他引:3
Iyer Prashant V. Thomas Susanna Lee Y. Y. 《Applied biochemistry and biotechnology》2000,84(1-9):665-677
Lactobacillus species capable of fermenting glucose are generally incapable of utilizing xylose for growth or fermentation. In this study,
a novel aspect of a well-known Lactobacillus strain, L. casei subsp. rhamnous (ATCC 10863), was uncovered: it can ferment xylose as efficiently as glucose. This strain is a registered organism, extremely
stable on long-term operation. Fermentation by this strain is characterized by an initial lag phase lasting 24–72 h before
xylose consumption takes place. The yield (grams/gram) of lactic acid from xylose is in excess of 80% with initial volumetric
productivity of 0.38 g/(L-h). Acetic acid is the primary byproduct formed at the level of about 10% of the lactic acid. In
addition to xylose, it can ferment all other minor sugars in hemicellulose except arabinose. Subjected to mixed sugar fermentation,
this strain consumes glucose first, then mannose, followed by almost simultaneous utilization of xylose and galactose. It
shows high tolerance for lactic acid as well as extraneous toxins. It can ferment the mixed sugars present in acid-treated
hydrolysate of softwood, giving yields similar to that of pure sugar but at a slower rate.
Author to whom all correspondence and reprint requests should be addressed. 相似文献
13.
Jia Ouyang Cong Cai Hai Chen Ting Jiang Zhaojuan Zheng 《Applied biochemistry and biotechnology》2012,168(8):2387-2397
Xylose is the major pentose and the second most abundant sugar in lignocellulosic feedstock. Its efficient utilization is regarded as a technical barrier to the commercial production of bulk chemicals from lignocellulosic biomass. This work aimed at evaluating the lactic acid production from the biomass-derived xylose using non-sterilized fermentation by Bacillus coagulans NL01. A maximum lactic acid concentration of about 75 g/L was achieved from xylose of 100 g/L after 72 h batch fermentation. Acetic acid and levulinic acid were identified as important inhibitors in xylose fermentation, which markedly reduced lactic acid productivity at 15 and 1.0 g/L, respectively. But low concentrations of formic acid (<2 g/L) exerted a stimulating effect on the lactic acid production. When prehydrolysate containing total 25.45 g/L monosaccharide was fermented with B. coagulans NL01, the same preference for glucose, xylose, and arabinose was observed and18.2 g/L lactic acid was obtained after 48 h fermentation. These results proved that B. coagulans NL01 was potentially well-suited for producing lactic acid from underutilized xylose-rich prehydrolysates. 相似文献
14.
Débora Danielle Virgínio da Silva Maria das Graças de Almeida Felipe Ismael Maciel de Mancilha Sílvio Silvério da Silva 《Applied biochemistry and biotechnology》2005,121(1-3):427-437
The effect of glucose on xylose-xylitol metabolism in fermentation medium consisting of sugarcane bagasse hydrolysate was
evaluated by employing an inoculum of Candida guilliermondii grown in synthetic media containing, as carbon sources, glucose (30 g/L), xylose (30 g/L), or a mixture of glucose (2 g/L)
and xylose (30 g/L). The inoculum medium containing glucose promoted a 2.5-fold increase in xylose reductase activity (0.582
IU/mgprot) and a 2-fold increase in xylitol dehydrogenase activity (0.203 IU/mgprot) when compared with an inoculum-grown medium containing only xylose. The improvement in enzyme activities resulted in higher
values of xylitol yield (0.56 g/g) and productivity (0.46 g/[L·h]) after 48 h of fermentation. 相似文献
15.
In pH-controlled batch fermentations with pure sugar synthetic hardwood hemicellulose (1% [w/v] glucose and 4% xylose) and
corn stover hydrolysate (8% glucose and 3.5% xylose) lacking acetic acid, the xyloseutilizing, tetracycline (Tc)-sensitive,
genomically integrated variant of Zymomonas mobilis ATCC 39676 (designated strain C25) exhibited growth and fermentation performance that was inferior to National Renewable
Energy Laboratory's first-generation, Tc-resistant, plasmid-bearing Zymomonas recombinants. With C25, xylose fermentation following glucose exhaustion wasmarkellyslower, and the ethanol yield (based
on sugars consumed) was lower, owing primarily to an increase in lactic acid formation. There was an apparent increased sensitivity
to acetic acid inhibition with C25 compared with recombinants 39676:pZB4L, CP4:pZB5, and ZM4:pZB5. However, strain C25 performed
well in continous ferm entation with nutrient-rich synthetic corn stover medium over the dilution range 0.03–0.06/h, with
a maximum provess ethanol yield at D=0.03/h of 0.46 g/g and a maximum ethanol productivity of 3 g/(L·h). With 0.35% (w/v) acetic acid in the medium, the process
yield at D=0.04/h dropped to 0.32 g/g, and the maximum productivity decreased by 50% to 1.5 g/(L·h). Under the same operating conditions,
rec Zm Zm 4:pZB5 performed better; however, the medium contained 20 mg/L of Tc to constantly maintain selective pressure.
The absence of any need for antibiotics and antiboitic resistance genes makes the chromosomal integrant C25 more com patible
with current regulatory specifications for biocatalysts in large-scale commercial operations. 相似文献
16.
Tae-Su Jeong Byung-Hwan Um Jun-Seok Kim Kyeong-Keun Oh 《Applied biochemistry and biotechnology》2010,161(1-8):22-33
Biological conversion of biomass into fuels and chemicals requires hydrolysis of the polysaccharide fraction into monomeric sugars prior to fermentation. Hydrolysis can be performed enzymatically or with mineral acids. In this study, dilute sulfuric acid was used as a catalyst for the pretreatment of rapeseed straw. The purpose of this study is to optimize the pretreatment process in a 15-mL bomb tube reactor and investigate the effects of the acid concentration, temperature, and reaction time. These parameters influence hemicellulose removal and production of sugars (xylose, glucose, and arabinose) in the hydrolyzate as well as the formation of by-products (furfural, 5-hydroxymethylfurfural, and acetic acid). Statistical analysis was based on a model composition corresponding to a 33 orthogonal factorial design and employed the response surface methodology to optimize the pretreatment conditions, aiming to attain maximum xylan, mannan, and galactan (XMG) extraction from hemicellulose of rapeseed straw. The obtained optimum conditions were: H2SO4 concentration of 1.76% and temperature of 152.6 °C with a reaction time of 21 min. Under these optimal conditions, 85.5% of the total sugar was recovered after acid hydrolysis (78.9% XMG and 6.6% glucan). The hydrolyzate contained 1.60 g/L glucose, 0.61 g/L arabinose, 10.49 g/L xylose, mannose, and galactose, 0.39 g/L cellobiose, 0.94 g/L fructose, 0.02 g/L 1,6-anhydro-glucose, 1.17 g/L formic acid, 2.94 g/L acetic acid, 0.04 g/L levulinic acid, 0.04 g/L 5-hydroxymethylfurfural, and 0.98 g/L furfural. 相似文献
17.
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
18.
Using the simultaneoussaccharification and fermentation (SSF) technique, pulp mill solid waste cellulose was converted into
glucose using cellulase enzyme and glucose into lacticacid using NRRL B445. SSF experiments were conducted at various pH levels,
temperatures, and nutrient concentrations, and the lactic acid yield ranged from 86 to 97%. The depletion of xylose in SSF
was further investigated by inoculating NRRL B445 into a xylose-only medium. On prolonged incubation, depletion of xylose
with lactic acid production was observed. An experimental procedure with a nonglucose medium was developed to eliminate the
lag phase. From xylose fermentation, Lactobacillus delbrueckii yielded 88–92% lactic acid and 2–12% acetic acid. 相似文献
19.
Balasubramanian Niru Seok Kim Jun Lee Y. Y. 《Applied biochemistry and biotechnology》2001,91(1-9):367-376
For optimum fermentation, fermenting xylose into acetic acid by Clostridium thermoaceticum (ATCC 49707) requires adaptation of the strain to xylose medium. Exposed to a mixture of glucose and xylose, it preferentially
consumesxylose over glucose. The initial concentration of xylose in the medium affects the final concentration and the yield
of acetic acid. Batch fermentation of 20 g/L of xylose with 5g/L of yeast extract as the nitrogen source results in a maximum
acetate concentration of 15.2 g/L and yield of 0.76 g of acid/g of xylose. Corn steep liquor (CLS) is a good substitute for
yeast extract and results in similar fermentation profiles. The organism consumes fructose, xylose, and glucose from a mixture
of sugars in batch fermentation. Arabinose, mannose, and galactose are consumed only slightly. This organism loses viability
on fed-batch operation, even with supplementation of all the required nutrients. In fed-batch fermentation with CSL supplementation,
d-xylulose (an intermediate in the xylose metabolic pathway) accumulates in large quantities. 相似文献
20.
Ozlem Akpinar Okan Levent Şeyda Bostanci Ufuk Bakir Levent Yilmaz 《Applied biochemistry and biotechnology》2011,163(2):313-325
Cotton stalk, a lignocellulosic waste material, is composed of xylose that can be used as a raw material for production of
xylitol, a high-value product. There is a growing interest in the use of lignocellulosic wastes for conversion into various
chemicals because of their low cost and the fact that they are renewable and abundant. The objective of the study was to determine
the effects of H2SO4 concentration, temperature, and reaction time on the production of sugars (xylose, glucose, and arabinose) and on the reaction
by-products (furfural and acetic acid). Response surface methodology was used to optimize the hydrolysis process in order
to obtain high xylose yield and selectivity. The optimum reaction temperature, reaction time, and acid concentration were
140 °C, 15 min, and 6%, respectively. Under these conditions, xylose yield and selectivity were found to be 47.88% and 2.26 g
g−1, respectively. 相似文献