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1.
Silva Silvio S. Ribeiro JoÃo D. Felipe Maria G. A. Vitolo Michelle 《Applied biochemistry and biotechnology》1997,(1):557-564
Batch fermentations of sugar cane bagasse hemicellulosic hydrolysate treated for removing the inhibitors of the fermentation
were performed byCandida guilliermondii FTI20037 for xylitol production. The fermentative parameters agitation and aeration rate were studied aiming the maximization
of xylitol production from this agroindustrial residue. The maximal xylitol volumetric productivity (0.87 g/L h) and yield
(0.67 g/g) were attained at 400/min and 0.45 v.v.m. (KLa 27/h). According to the results, a suitable control of the oxygen input permitting the xylitol formation from sugar cane
bagasse hydrolysate is required for the development of an efficient fermentation process for large-scale applications. 相似文献
2.
Rosa S. M. A. Felipe M. G. A. Silva S. S. Vitolo M. 《Applied biochemistry and biotechnology》1998,(1):127-135
The effect of pH, time of fermentation, and xylose and glucose concentration on xylitol production, cell growth, xylose reductase
(XR), and xylitol dehydrogenase (XD) activities ofCandida guilliermondii FTI 20037 were determined. For attaining XR and XD activities of 129-2190 U/mg of protein and 24-917 U/mg of protein, respectively,
the cited parameters could vary as follows: initial pH: 3.0-5.0; xylose: 15-60 g/L; glucose: 0-5 g/L; and fermentation time:
12-24 h. Moreover, the high XR and XD activities occurred when the xylitol production by the yeast was less than 19.0 g/L. 相似文献
3.
Mayerhoff Zea D. V. L. Roberto Inês C. Franco Telma T. 《Applied biochemistry and biotechnology》2001,91(1-9):729-737
Xylose reductase (XR) activity was evaluated in extracts of Candida mogii grown in media containing different concentrations of rice straw hydrolysate. Results of X Ractivity were compared to xylitol
production and a similar behavior was observed for these parameters. Highest values of specific production and productivity
were found for xylose reductase (35 U/g of cell and 0.97 U/[g of cell·h], respectively) and for xylitol (5.63 g/g of cell
and 0.13 g/[g of cell·h]) in fermentation conducted in medium containing 49.2 g of xylose/L. The maximum value of XR:XD ratio
(1.82) was also calculated under this initial xylose concentration with 60 h of fermentation. 相似文献
4.
Eliana V. Canettieri João B. Almeida E. Silva Maria G. A. Felipe 《Applied biochemistry and biotechnology》2001,94(2):159-168
This study deals with the bioconversion of xylose into xylitol by Candida guilliermondii FTI 20037 using eucalyptus hemicellulosic hydrolysate obtained by acid hydrolysis. The influence of various parameters (ammonium
sulfate, rice bran, pH, and xylose concentration) on the production of xylitol was evaluated. The experiments were based on
multivariate statistical concepts, with the application of factorial design techniques to identify the most important variables
in the process. The levels of these variables were quantified by the response surface methodology, which permitted the establishment
of a significant mathematical model with a coefficient determination of R
2=0.92. The best results (xylitol=10.0 g/L, yield factor=0.2 g/g, and productivity=0.1 g/[L·h]) were attained with hydrolysate
containing ammonium sulfate (1.1 g/L), rice bran (5.0 g/L), and xylose (initial concentration of 60.0 g/L), after 72 h of
fermentation. The pH of fermentation was adjusted to 8.0 and the inoculum level utilized was 3 g/L. 相似文献
5.
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
6.
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
7.
Inês C. Roberto Ismael M. de Mancilha Sunao Sato 《Applied biochemistry and biotechnology》1999,77(1-3):205-210
The fermentation kinetics for the conversion of rice straw hemicellulosic hydrolysate to xylitol by the yeast Candida guilliermondii was evaluated under batch conditions. The fermentation was accomplished in a 1 L working volume stirred-tank reactor with
aeration of 1.3 vvm and agitation of 300 rpm (kLa=15/h). The maximum specific rate of xylitol formation (0.12 g/g) was achieved when the specific growth rate was lowered
to 1/5 of its highest value. From analysis of the fermentation kinetics, a linear correlation between specific growth rate
(μx) and specific rate of xylitol formation (qp) was evident. Based on the Gaden model, this bioprocess was classified as growth-associated production and the relationship
between μx and qp can be described by the equation qp=6.31μx. 相似文献
8.
Mayerhoff Z. D. V. L. Roberto I. C. Silva S. S. 《Applied biochemistry and biotechnology》1998,(1):149-159
The influence of aeration level, initial pH, initial cell concentration, and fermentation time on the xylitol production from
rice straw hemicellulose hydrolysate byCandida mogii was studied. A multifactorial experimental design was adopted to evaluate this influence. A statistical analysis of the results
showed that the aeration level and the initial pH had significant effects on yield factor, volumetric productivity, and xylose
consumption. For the latter, fermentation time was also a significant variable. Based on the response surface methodology,
models for the range investigated were proposed. The maximum values for the yield factor (Yp/s) and volumetric productivity (Qp) were, respectively, 0.71 g/g and 0.46 g(Lh). 相似文献
9.
The effects of oxygen limitation on xylose fermentation of Neurospora crassa AS3.1602 were studied using batch cultures. The maximum yield of ethanol was 0.34 g/g at oxygen transfer rate (OTR) of 8.4 mmol/L·h.
The maximum yield of xylitol was 0.33 g/g at OTR of 5.1 mmol/L·h. Oxygen limitation greatly affected mycelia growth and xylitol
and ethanol productions. The specific growth rate (μ) decreased 82% from 0.045 to 0.008 h−1 when OTR changed from 12.6 to 8.4 mmol/L·h. Intracellular metabolites of the pentose phosphate pathway, glycolysis, and tricarboxylic
acid cycle were determined at various OTRs. Concentrations of most intracellular metabolites decreased with the increase in
oxygen limitation. Intracellular enzyme activities of xylose reductase, xylitol dehydrogenase, and xylulokinase, the first
three enzymes in xylose metabolic pathway, decreased with the increase in oxygen limitation, resulting in the decreased xylose
uptake rate. Under all tested conditions, transaldolase and transketolase activities always maintained at low levels, indicating
a great control on xylose metabolism. The enzyme of glucose-6-phosphate dehydrogenase played a major role in NADPH regeneration,
and its activity decreased remarkably with the increase in oxygen limitation. 相似文献
10.
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
11.
Rodrigues Denise C. G. A. Da Silva Silvio S. Almeida E Silva J. B. Vitolo Michele 《Applied biochemistry and biotechnology》2002,98(1-9):875-883
Xylose reductase activity of Candida guilliermondii FTI 20037 was evaluated during xylitol production by fed-batch fermentation of sugarcane bagasse hydrolysate. A 24-1 fractional factorial design was used to select process variables. The xylose concentrations in the feeding solution (S
F
) and in the fermentor (S
0), the pH, and the aeration rate were selected for optimization of this process, which will be undertaken in the near future.
The best experimental result was achieved at S
F
=45 g/L, S
0=40 g/L, pH controlled at 6.0, and aeration rate of 1.2 vvm. Under these conditions, the xylose reductase activity was 0.81
U/mg of protein and xylitol production was 26.3 g/L, corresponding to a volumetric productivity of 0.55 g/(L·h) and a xylose
xylitol yield factor of 0.68 g/g. 相似文献
12.
Ernesto Acosta Martínez Silvio S. Silva Maria G. A. Felipe 《Applied biochemistry and biotechnology》1999,77(1-3):347-354
The biocon version of xylose intoxylitol using pH values of 4.0, 5.5 and 7.0 and tetracycline concentrations of 20 and 40
mg/L was carried out to verify the influence of these parameters on Candida guilliermondii metabolism for xylitol production. Experiments were performed with sugarcane bagasse hemicellulosi chydrolysate (48.5 g/L
of xylose) in 125-mL Erlenmeyer flasks, at 30°C, 200 rpm, during 88 h. The results demostrated that the bioconversion of xylose
into xylitol was significantly influenced by the pH. On the other hand, in media containing 20 or 40 mg/L of tetracycline,
this bioconversion was not significantly affected. The best results of xylitol production were obtained in hemicellulosic
hydrolysate without tetracycline, at pH 7.0 In these conditions, the maxim um specific growth rate was 0.014/h and the yield
factor of xylitol and volumetric productivity were 0.85g/g and 0.70g/L/h respectively. Xylitol and cell growth occureed simultaneously. 相似文献
13.
PVA-Hydrogel Entrapped <Emphasis Type="Italic">Candida Guilliermondii</Emphasis> for Xylitol Production from Sugarcane Hemicellulose Hydrolysate 总被引:1,自引:0,他引:1
da Cunha MA Converti A Santos JC Ferreira ST da Silva SS 《Applied biochemistry and biotechnology》2009,157(3):527-537
Viable cells of Candida guilliermondii were immobilized by inclusion into polyvinyl alcohol (PVA) hydrogel using the freezing–thawing method. Entrapment experiments
were planned according to a 23 full factorial design, using the PVA concentration (80, 100, and 120 g L−1), the freezing temperature (−10, −15, and −20 °C), and the number of freezing-thawing cycles (one, three, and five) as the
independent variables, integrated with three additional tests to estimate the errors. The effectiveness of the immobilization
procedure was checked in Erlenmeyer flasks as the pellet capability to catalyze the xylose-to-xylitol bioconversion of a medium
based on sugarcane bagasse hemicellulosic hydrolysate. To this purpose, the yield of xylitol on consumed xylose, xylitol volumetric
productivity, and cell retention yield were selected as the response variables. Cell pellets were then used to perform the
same bioconversion in a stirred tank reactor operated at 400 rpm, 30 °C, and 1.04 vvm air flowrate. At the end of fermentation,
a maximum xylitol concentration of 28.7 g L−1, a xylitol yield on consumed xylose of 0.49 g g−1 and a xylitol volumetric productivity of 0.24 g L−1 h−1 were obtained. 相似文献
14.
Gimenes Maria Antonieta P. Carlos Luiz Cláudio S. Faria Luís F. F. Pereira Nei 《Applied biochemistry and biotechnology》2002,98(1-9):1049-1059
The global oxygen uptake rate (OUR) and specific oxygen uptake rates (SOUR) were determined for different values of the volumetric
oxygen mass transfer coefficient (15, 43, and 108 h−1), and for varying initial xylose concentrations (50, 100, 150, and 200 g/L) in shaking flasks. The initial cell concentration
was 4.0 g/L, and there was only significant growth in the fermentation with the highest oxygen availability. In this condition,
OUR increased proportionally to cell growth, reaching maximum values from 2.1 to 2.5 g of O2/(L·h) in the stationary phase when the initial substrate concentration was raised from 50 to 200 g/L, respectively. SOUR
showed different behavior, growing to a maximum value coinciding with the beginning of the exponential growth phase, after
which point it decreased. The maximum SOUR values varied from 265 to 370 mg of O2/(g of cell·h), indicating the interdependence of this parameter and the substrate concentration. Although the volumetric
productivity dropped slightly from 1.55 to 1.18 g of xylitol/(L·h), the strain producing capacity (γ
P/X
) rose from 9 to 20.6 g/g when the initial substrate concentration was increased from 50 to 200 g/L. As for the xylitol yield
over xylose consumed (γ
P/S
), there was no significant variation, resulting in a mean value of 0.76 g/g. The results are of interest in establishing
a strategy for controlling the dynamic oxygen supply to maximize volumetric productivity. 相似文献
15.
Cao Ning-Jun Tang Rentian Gong C. S. Chen L. F. 《Applied biochemistry and biotechnology》1994,(1):515-519
The rate of xylitol production from D-xylose increased with increasing yeast cell density. The optimal temperature for xylitol
production is 36‡ C, and the optimal pH range is from 4.0 to 6.0. At high initial yeast cell concentration of 26 mg/mL, 210
g/L of xylitol was produced from 260 g/L of D-xylose after 96 h of incubation with an indicated yield of 81% of the theoretical
value. 相似文献
16.
De Carvalho M. E. A. Monteiro M. C. Bon E. P. S. Sant’Anna G. L. 《Applied biochemistry and biotechnology》1998,(1):955-966
The production of lignin peroxidase fromPhanerochaete chrysosporium was studied using immobilized mycelia in nylon-web cubes in semicontinuous fermentation using glucose pulses or ammonium
tartrate pulses. Consistent enzyme production was achieved when glucose pulses were used, leading to an average activity of
253 U/L. The crude enzyme was added to eucalyptus kraft pulp before conventional and ECF bleaching sequences. Optimization
of the enzymatic pretreatment led to the following operational conditions: enzyme load of 2 U/g of pulp, hydrogen peroxide
addition rate of 10 ppm/h, and reaction time of 60 min. Pulp final characteristics were dependent on the chemical treatment
sequence that followed enzymatic pretreatment. The chief advantage of enzymatic pretreatment was pulp viscosity preservation,
which was observed in most of the experiments carried out with seven different chemical treatment sequences 相似文献
17.
Martínez Ernesto Acosta Silva Silvio S. Felipe Maria G. A. 《Applied biochemistry and biotechnology》2000,84(1-9):633-641
The effect of the oxygen transfer coefficient on the production of xylitol by biocon version of xylose present in sugarcane
bagasse hemicellulosic hydrolysate using the yeast Candiada guilliermondii was investigated. Continuous cultivation was carried out in a 1.25-L fermentor at 30°C, pH 5.5, 300 rpm, and a dilution rate
of 0.03/h, using oxygen transfer coefficients of 10,20, and 30/h. The results showed that the microbial xylitol production
(11 g/L) increased by 108% with the decrease in the oxygen volumetric transfer coefficient from 30 to 20/h. The maximum values
of xylitol productivity (0.7g/[L…h]) and yield (0.58 g/g) were obtained at k
L
a 20/h. 相似文献
18.
Sene L. Vitolo M. Felipe M. G. A. Silva S. S. 《Applied biochemistry and biotechnology》2000,84(1-9):371-380
The effects of environmental conditions, namely initial pH (2.5–7.0) and temperature (25 and 35°C), on xylose reductase and
xylitol dehydrogenase levels, as well as on xylitol production, were evaluated. Although the fermentative parameter values
increased with an increase in pH and temperature (the maximum YP/s and Q
p
were 0.75 g/g and 0.95 g/[L·h], respectively, both attained at pH 6.0, 35°C), the highest xylose reductase activities (nearly
900 1U/mg of protein) were observed at an initial pH varying from 4.0 to 6.0. Xylitol dehydrogenase was favored by an increase
in both initial pH and temperature of the medium. The highest xylitol dehydrogenase specific activity was attained at pH 6.5
and 35°C (577 1U/mg of protein). 相似文献
19.
Júlio C. Santos Ícaro R. G. Pinto Walter Carvalho Ismael M. Mancilha Maria G. A. Felipe Silvio S. Silva 《Applied biochemistry and biotechnology》2005,122(1-3):673-683
Xylose-to-xylitol bioconversion was performed utilizing Candida guillier-mondii immobilized in sugarcane bagasse and cultured in Erlenmeyer flasks using sugarcane bagasse hydrolysate as the source of xylose.
Fermentations were carried out according to a factorial design, and the independent variables considered were treatment, average
diameter, and amount of bagasse used as support for cell immobilization. By increasing the amount of support, the xylitol
yield decreased, whereas the biomass yield increased. The diameter of the support did not influence xylitol production, and
treatment of the bagasse with hexamethylene diamine prior to fermentation resulted in the highest amount of immobilized cells. 相似文献
20.
A mutant strain ofPichia stipitis, FPL-061, was obtained by selecting for growth on L-xylose in the presence of respiratory inhibitors. The specific fermentation
rate of FPL-061, was higher than that of the parent,Pichia stipitis CBS 6054, because of its lower cell yield and growth rate and higher specific substrate uptake rate. With a mixture of glucose
and xylose, the mutant strain FPL-061 produced 29.4 g ethanol/L with a yield of 0.42 g ethanol/g sugar consumed. By comparison,
CBS 6054 produced 25.7 g ethanol/L with a yield of 0.35 gJg. The fermentation was most efficient at an aeration rate of 9.2
mmoles O2 L-1 h-1. At high aeration rates (22 mmoles O2 L-1 h-1), the mutant cell yield was less than that of the parent. At low aeration rates, (1.1 to 2.5 O2 L-1 h-1), cell yields were similar, the ethanol formation rates were low, and xylitol accumulation was observed in both the strains.
Both strains respired the ethanol once sugar was exhausted. We infer from the results that the mutant, P.stipitis FPL-061, diverts a larger fraction of its metabolic energy from cell growth into ethanol production. 相似文献