共查询到20条相似文献,搜索用时 31 毫秒
1.
S. M. Lastick M. Y. Tucker J. R. Beyette G. B. Noll K. Grohmann 《Applied microbiology and biotechnology》1989,30(6):574-579
Summary Ethanol was produced from xylose by converting the sugar to xylulose, using commercial xylose isomerases, and simultaneously converting the xylulose to ethanol by anaerobic fermentation using different yeast strains. The process was optimized with the yeast strain Schizosaccharomyces pombe (Y-164). The data show that the simultaneous fermentation and isomerization of 6% xylose can produce final ethanol concentrations of 2.1% w/v within 2 days at temperatures as high as 39°C.Nomenclature SFIX
simultaneous fermentation and isomerization of xylose
-
V
p
volumetric production (g ethanol·l-1 per hour)
-
Q
p
specific rate (g ethanol·g-1 cells per hour)
-
Y
s
yield from substrate consumed (g ethanol, g-1 xylose)
- ET
ethanol concentration (% wt/vol)
- XT
xylitol concentration (% wt/vol)
- Glu
glucose
- Xyl
xylose
- --m
maximum
- --f
final 相似文献
2.
Carol Líliam Coelho Silva Carlos Augusto Rosa Evelyn Souza Oliveira 《World journal of microbiology & biotechnology》2006,22(8):857-863
Summary The growing demand for high quality products and the immense export potential that cacha?a represents, demonstrated especially during the past few years, have clearly indicated the necessity of establishing well-defined standards of quality, as well as effective means of controlling the process of production of this beverage. The objective of this study was the selection of S. cerevisiae yeast strains and the investigation of their influence on the kinetic parameters of fermentation. Ninety strains of S. cerevisiae isolated from distilleries of the state of Minas Gerais were evaluated with respect to the following parameters: flocculation capacity, production of H2S and kinetic parameters of fermentation. The UFMGA 905 strain was used as a reference because it presented desirable characteristics for the production of cacha?a. Five strains presented high specific sedimentation velocities (SSV), indicating a high flocculation capacity, and two did not produce H2S. The strains presented significant statistical differences for fermentation parameters: yield of ethanol; efficiency of substrate conversion to ethanol; ratio of substrate conversion to ethanol (Y
p/s), to cells (Y
x/s), to organic acids (Y
ac/s), and to glycerol (Y
g/s); and productivity. In general, the strains presented a good fermentative potential, with ethanol yields varying from 74.7 to 82.1% and an efficiency of 76.1–84.4%. All strains presented high productivities (4.6–6.6 g l−1 h−1), indicating that this parameter can be used in the selection of strains for the production of cacha?a. 相似文献
3.
Evelyn Souza Oliveira Carlos A. Rosa Marcelo Antonio Morgano Gil Eduardo Serra 《World journal of microbiology & biotechnology》2004,20(1):19-24
The fermentation characteristics of 24 strains of Saccharomyces cerevisiae and one strain of Candida apicola, C. famata, C. guilliermondii, Hanseniospora occidentalis, Pichia subpelicullosa and Schizosaccharomyces pombe were evaluated for the production of cachaça. They were isolated from small cachaça distilleries (27), industrial cachaça distilleries (2) and one sugarcane alcohol distillery. The yeasts showed significant differences in ethanol yield, substrate conversion, efficiency, conversion factors of substrate into ethanol (Y
p/s), cells (Y
x/s), organic acids (Y
ac/s) and glycerol (Y
g/s), and maximum specific growth rate (
max). In general the S. cerevisiae strains showed better fermentation potential, with yields between 83 and 91% and
max between 0.450 and 0.640 h–1, several of them being comparable with the high performance yeast used in the industrial production of ethanol, which was adopted as a reference. The non-Saccharomyces strains showed high efficiency, very low ethanol yield and very high Y
ac/s and Y
g/s values, except Pichia subpelliculosa, which behaved very similarly to the S. cerevisiae strains. Hierarchical Cluster Analysis and Principal Component Analysis showed the fermentation yield (or substrate conversion) as being the variable which contributed most to the separation of the strains into different groups. 相似文献
4.
This study evaluated the conventional jet cooking liquefaction process followed by simultaneous saccharification and fermentation (SSF) at 30% and 35% dry solids (DS) concentration of Indian sorghum feedstock for ethanol production, with addition of acid fungal protease or urea. To evaluate the efficacy of thermostable α‐amylase in liquefaction at 30% and 35% DS concentration of Indian sorghum, liquefact solubility, higher dextrins, and fermentable sugars were analyzed at the end of the process. The liquefact was further subjected to SSF using yeast. In comparison with urea, addition of an acid fungal protease during SSF process was observed to accelerate yeast growth (μ), substrate consumption (Qs), ultimately ethanol yield based on substrate (Yp/s) and ethanol productivity based on fermentation time (Qp). The fermentation efficiency and ethanol recovery were determined for both concentrations of Indian sorghum and found to be increased with use of acid fungal protease in SSF process. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29: 329–336, 2013 相似文献
5.
Ethanol production from hardwood spent sulfite liquor using an adapted strain of Pichia stipitis 总被引:1,自引:0,他引:1
J N Nigam 《Journal of industrial microbiology & biotechnology》2001,26(3):145-150
Conditions have been optimized for fermentation of pretreated hardwood spent sulfite liquor (HSSL) using an adapted strain
of Pichia stipitis. The pretreatments, consisting of boiling and overliming with Ca(OH)2 of HSSL, to partially remove inhibitors, and adaptation of the yeast strain to HSSL, were both critical for a successful
fermentation. Ethanol concentration was increased from 6.7 to 20.2 g l−1 using adapted P. stipitis (A) and pretreated HSSL. The maximum ethanol yield (Y
p/s) and productivity (Q
p) were 0.41 g g−1 and 0.44 g l−1 h−1, respectively, at an oxygen transfer rate of 2.0 mmol O2 l−1 h−1. The optimized results with this strain were compared to those of other xylose-fermenting yeasts and Saccharomyces cerevisiae (SSL-acclimatized) currently used at an industrial plant for the fermentation of spent sulfite liquor. Journal of Industrial Microbiology & Biotechnology (2001) 26, 145–150.
Received 23 June 2000/ Accepted in revised form 21 October 2000 相似文献
6.
Lakkana Laopaiboon Pornthap Thanonkeo Prasit Jaisil Pattana Laopaiboon 《World journal of microbiology & biotechnology》2007,23(10):1497-1501
Sweet sorghum juice supplemented with 0.5% ammonium sulphate was used as a substrate for ethanol production by Saccharomyces cerevisiae TISTR 5048. In batch fermentation, kinetic parameters for ethanol production depended on initial cell and sugar concentrations.
The optimum initial cell and sugar concentrations in the batch fermentation were 1 × 108 cells ml−1 and 24 °Bx respectively. At these conditions, ethanol concentration produced (P), yield (Y
ps) and productivity (Q
p
) were 100 g l−1, 0.42 g g−1 and 1.67 g l−1 h−1 respectively. In fed-batch fermentation, the optimum substrate feeding strategy for ethanol production at the initial sugar
concentration of 24 °Bx was one-time substrate feeding, where P, Y
ps and Q
p
were 120 g l−1, 0.48 g g−1 and 1.11 g l−1 h−1 respectively. These findings suggest that fed-batch fermentation improves the efficiency of ethanol production in terms of
ethanol concentration and product yield. 相似文献
7.
pH affected significantly the growth and the glucose fermentation pattern of Propionibacterium microaerophilum. In neutral conditions (pH 6.5–7.5), growth and glucose fermentation rate (qs) were optimum producing propionate, acetate,
CO2, and formate [which together represented 90% (wt/wt) of the end products], and lactate representing only 10% (wt/wt) of the
end products. In acidic conditions, propionate, acetate, and CO2 represented nearly 100% (wt/wt) of the fermentation end products, whereas in alkaline conditions, a shift of glucose catabolism
toward formate and lactate was observed, lactate representing 50% (wt/wt) of the fermentation end products. The energy cellular
yields (Y
X/ATP), calculated (i) by taking into account extra ATP synthesized through the reduction of fumarate into succinate, was 6.1–7.2
g mol−1. When this extra ATP was omitted, it was 11.9–13.1 g mol−1. The comparison of these values with those of Y
X/ATP in P. acidipropionici and other anaerobic bacteria suggested that P. microaerophilum could not synthesize ATP through the reduction of fumarate into succinate and therefore differed metabolically from P. acidipropionici.
Received: 8 April 2002 / Accepted: 8 May 2002 相似文献
8.
Summary The performance ofZymomonas mobilis strains ATCC 31821 and ATCC 31823 was assessed in batch and continuous culture. In batch culture using a medium containing 250 g/l glucose, identical maximum specific growth rates of 0.16/h were found, though final biomass concentration and growth yield were significantly lower for ATCC 31 823 than for ATCC 31 821. Final ethanol concentrations in this medium were about 110 g/l vor both organisms. In continuous culture at increasing dilution rates using a medium containing 100 g/l glucose, no significant differences were seen between the two strains with respect to the fermentation parameters studied. For ATCC 31 821, maximum rates of glucose uptake (Qs) and ethanol produktion (Qp) of 8.7 g glu/g/h and 4.4 g eth/g/h, respectively, were found. Both strains showed a similar performance at a fixed dilution rate of 0.1/h, where maximum ethanol concentrations of about 68 g/l were reached at a feed glucose concentration of about 139 g/l. At this dilution rate the maximum values of Qs and Qp were about 5.8 g glu/g/h and 2.8 g eth/g/h, respectively. Test tube experiments showed that growth, measured as optical density, decreased with increasing concentrations of exogenous ethanol with complete inhibition of growth at ethanol concentrations >8% (v/v). As evidenced by the results presented here, we have been unable to practice the invention as described in U.S. Patent 4,403,034 (Rogers and Tribe 1983).Nomenclature D
Dilution rate, 1/h
- max
maximum specific growth rate, 1/h
- SR
Initial substrate concentration, g glucose/1
- S
Residual substrate concentration, g glucose/1
- S0
Effluent substrate concentration, g glucose/1
- X
Blomass concentration; g cells/l
- OD620
Optical density at 620 nm, dimensionless
- [P]
Product concentration, g ethanol/1
- Yx/s
Growth yield, g cells/g glucose used
- Yp/s
Product yield, g ethanol/g glucose used
- %, Yield
Percentage yield, Yp/sx100/Y
p
s/max
=Yp/sx100/0.51
- Qs
Specific rate of glucose uptake, g glucose/g cells/h
- Qp
Specific rate of ethanol formation, g ethanol/g cells/h
- me
Maintenance energy coefficient, g glucose/g cells/h
- VP
Volumetric productivity, g ethanol/l/h
- t
Fermentation time, h 相似文献
9.
Summary Fed-batch fermentation of non-supplemented concentrated whey permeate resulted in high ethanol productivity for feeds of lactose for which batch fermentation had a poor performance. At an initial lactose concentration of 100 g/L and a constant lactose feeding rate of 18 g/h we have obtained: ethanol concentration 64 g/L, ethanol productivity 3.3 g/Lh, lactose consumption 100%, ethanol yield 0.47 g/g, and biomass yield 0.058 g/g.Nomenclature St
total lactose fed per medium volume in the bioreactor, g/L
- Si
initial lactose concentration, g/L
- F
lactpse feeding rate, g/h
- P
final ethanol concentration, g/L
- Yp/s
ethanol yield, g ethanol/g lactose
- Yx/s
biomass yield, g biomass/g lactose
- XS
lactose consumption, %
- Qp
overall ethanol volumetric productivity, g/Lh
- m
maximum specific growth rate, h
- qsm
maximum specific lactose consumption rate, g/gh
- qpm
maximum specific ethanol production rate, g/gh 相似文献
10.
A. Sanromán E. Roca M. J. Núñez Professor Dr. J. M. Lema 《Bioprocess and biosystems engineering》1994,10(2):75-81
When the immobilized cells are employed in packed-bed bioreactors several problems appear. To overcome these drawbacks, a new bioreactor based on the use of pulsed systems was developed [1]. In this work, we study the glucose fermentation by immobilized Saccharomyces cerevisiae in a packed-bed bioreactor. A comparative study was then carried out for continuous fermentation in two packed-bed bioreactors, one of them with pulsed flow. The determination of the axial dispersion coefficients indicates that by introducing the pulsation, the hydraulic behaviour is closer to the plug flow model. In both cases, the residence time tested varied from 0.8 to 2.6 h. A higher ethanol concentration and productivity (increases up to 16%) were achieved with the pulsated reactors. The volumes occupied by the CO2 were 5.22% and 9.45% for fermentation with/without pulsation respectively. An activity test of the particles from the different sections revealed that the concentration and viability of bioparticles from the two bioreactors are similar. From the results we conclude that the improvements of the process are attributable to a mechanical effect rather than to physiological changes of microorganisms.List of Symbols
D m2/s
dispersion coefficient
-
K
is l/g
inhibition substrate constant
-
K
ip l/g
inhibition ethanol constant
-
K
s g/l
Apparent affinity constant
-
P g/l
ethanol concentration
-
q
p g/(gh)
specific ethanol productivity
-
Q
p g/(lh)
overall ethanol productivity
-
q
s g/(gh)
specific glucose consumption rate
-
Q
s g/(lh)
glucose consumption rate
-
S g/l
residual glucose concentration
-
S(in0) g/l
initial glucose concentration
-
V
max g/(lh)
maximum rate
-
Y
p/s g/g
yield in product 相似文献
11.
Summary In an effort to establish the reasons for the limitations in the final ethanol concentration of Zymomonas mobilis fermentation, the effects of CO2 and ethanol on the fermentation were investigated using continuous and fed-batch cultivation systems. The nucleation and
stripping out of CO2 from the fermenter using diatomaceous earth or nitrogen gas or both exhibited a profound effect on the glucose uptake rate
during the early stages of fed-batch fermentation, but did not improve final ethanol yields. The addition of ethanol together
with above mentioned experiments confirmed conclusively that ethanol inhibition is responsible for the final ethanol concentration
obtainable during Zymomonas mobilis fermentation. The final concentration lies between 90 and 110 gl−1 or approximately 12–15% (v/v) ethanol. 相似文献
12.
《Journal of Fermentation Technology》1986,64(4):293-297
Simultaneous saccharification and ethanol fermentation (SSF) of sago starch using amyloglucosidase (AMG) and immobilized Zymomonas mobilis ZM4 on sodium alginate was studied. The immobilized Zymomonas cells were more thermo-stable than free Zymomonas cells in this system. The optimum temperature in the SSF system was 40°C, and 0.5% (v/w) AMG concentration was adopted for the economical operation of the system. The final ethanol concentration obtained was 68.3 g/l and the ethanol yield, Yp/s, was 0.49 g/g (96% of the theoretical yield). After 6 cycles of reuse at 40°C with 15% sago starch hydrolysate, the immobilized Z. mobilis retained about 50% of its ethanol fermenting ability. 相似文献
13.
Cellulase, Tween 80, and β-glucosidase loading were studied and optimized by response surface methodology to improve saccharification.
Microwave alkali-pretreated rice straw used as substrate for onsite enzyme production by Aspergillus heteromorphus and Trichoderma reesei. The highest enzymatic hydrolysis (84%) was obtained from rice straw at crude enzyme loading of 10 FPU/gds of cellulase,
0.15% Tween 80, and 100 international unit/g dry solids of β-glucosidase activities. Enzymatic hydrolyzate of pretreated rice
straw was used for ethanol production by Saccharomyces cerevisiae, Scheffersomyces stipitis, and by co-culture of both. The yield of ethanol was 0.50, 0.47, and 0.48 gp/gs by S. cerevisiae, S. stipitis, and by co-culture, respectively, using pretreated rice straw hydrolyzate. The co-culture of S. cerevisiae and S. stipitis produced 25% more ethanol than S. cerevisiae alone and 31% more ethanol than S. stipitis alone. During anaerobic fermentation 65.08, 36.45, and 50.31 μmol/ml CO2 released by S. cerevisiae, S. stipitis, and by co-culture, respectively. The data indicated that saccharification efficiency using optimized crude enzyme cocktail
was good, and enzymatic hydrolyzate could be fermented to produce ethanol. 相似文献
14.
Summary The fermentation of an equimolar mixture of glucose and fructose into ethanol and sorbitol by a fructose negative mutant of Zymomonas mobilis is analysed using a recently described methodology (Ait-Abdelkader and Baratti, Biotechnol. Tech. 1993,329–334) based on polynomial fitting and calculation of instantaneous and overall parameters. These parameters are utilized to describe this mixed-substrate mixed-product fermentation.Nomenclature X
biomass concentration, g/l
- S
total sugar concentration, g/l
- Glu
glucose concentration, g/l
- Fru
fructose concentration, g/l
- Sor
sorbitol concentration, g/l
- P
ethanol concentration, g/l
- t
fermentation time, h
-
specific growth rate, h-1
- qs
specific sugar uptake rate, g/g.h
- qg
specific glucose uptake rate, g/g.h
- qF
specific fructose uptake rate, g/g.h
- qP
specific ethanol productivity, g/g.h
- qSor
specific sorbitol productivity, g/g.h
- YX/S
biomass yield on total sugar, g/g
- YP/S
ethanol yield on total sugar, g/g
- YSor/S
sorbitol yield on total sugar, g/g
- YSor/F
sorbitol yield on fructose, (g/g)
- YP/G
ethanol yield on glucose, (g/g) 相似文献
15.
The aim of this study was to systematically obtain a model of factors that would yield an optimized self-nanoemulsified capsule
dosage form (SNCDF) of a highly lipophilic model compound, Coenzyme Q10 (CoQ). Independent variables such as amount of R-(+)-limonene
(X
1), surfactant (X
2), and cosurfactant (X
3), were optimized using a 3-factor, 3-level Box-Behnken statistical design. The dependent variables selected were cumulative
percentage of drug released after 5 minutes (Y
1) with constraints on drug release in 15 minutes (Y
2), turbidity (Y
3), particle size (Y
4), and zeta potential (Y
5). A mathematical relationship obtained,Y
1=78.503+6.058X
1 +13.738X
2+5.986X
3−25.831X
1
2
+9.12X
1X2−26.03X
1X3−38.67X
2
2
+11.02X
2X3−15.55X
3
3
(r
2=0.97), explained the main and quadratic effects, and the interaction of factors that affected the drug release. Response
surface methodology (RSM) predicted the levels of factorsX
1,X
2, andX
3 (0.0344, 0.216, and 0.240, respectively), for a maximized response ofY
1 with constraints of >90% release onY
2. The observed and predicted values ofY
1 were in close agreement. In conclusion, the Box-Behnken experimental design allowed us to obtain SNCDF with rapid (>90%)
drug release within 5 minutes with desirable properties of low turbidity and particle size. 相似文献
16.
Jie Feng Xiao-Bei Zhan Dong Wang Li-Min Zhang Chi-Chung Lin 《Biotechnology and Bioprocess Engineering》2012,17(2):242-249
Salt-tolerant aromatic yeast is an important microorganism arising from the solid state fermentation of soy sauce. The fermentation
kinetics of volatile esters by Candida etchellsii was studied in a batch system. The data obtained from the fermentation were used for determining the kinetic parameters of
the model. Batch experimental results at four NaCl levels (180, 200, 220, and 240 g/L) were used to formulate the parameter
estimation model. The kinetic parameters of the model were optimized by specifically designed Runge-Kutta Genetic Algorithms
(GA). The resulting mathematical model for volatile ester production, cell growth and glucose consumption simulates the experimental
data well. The resulting new model was capable of explaining the behavior of volatile ester fermentation. The optimized parameters
(μo, X
max, K
i, α, β, Y
X/S, m, and Y
P/S) were characterized by a correlation of functions assuming salinity dependence. The kinetic models optimized by GA describe
the batch fermentation process adequately, as demonstrated by our experimental results. 相似文献
17.
The oxygen requirements of yeasts for the fermentation of d-xylose and d-glucose to ethanol 总被引:1,自引:0,他引:1
Magdalena E. Ligthelm Bernard A. Prior James C. du Preez 《Applied microbiology and biotechnology》1988,28(1):63-68
Summary The effect of oxygen availability on d-xylose and D-glucose metabolism by Pichia stipitis, Candida shehatae and Pachysolen tannophilus was investigated. Oxygen was not required for fermentation of d-xylose or d-glucose, but stimulated the ethanol production rate from both sugars. Under oxygen-limited conditions, the highest ethanol yield coefficient (Ye/s) of 0.47 was obtained on d-xylose with. P. stipitis, while under similar conditions C. shehatae fermented d-xylose most rapidly with a specific productivity (qpmax) of 0.32 h-1. Both of these yeasts fermented d-xylose better and produced less xylitol than. P. tannophilus. Synthesis of polyols such as xylitol, arabitol, glycerol and ribitol reduced the ethanol yield in some instances and was related to the yeast strain, carbon source and oxygen availability. In general, these yeasts fermented d-glucose more rapidly than d-xylose. By contrast Saccharomyces cerevisiae fermented d-glucose at least three-fold faster under similar conditions.Nomenclature qpmax
maximum specific rate of ethanol production (g ethanol per g dry biomass per hour)
- Ye/s
ethanol yield (g ethanol per g substrate utilized)
- Yp/s
polyol yield (g polyol per g substrate utilized)
- Yx/s
biomass yield (g dry biomass per g substrate utilized)
- max
maximum specific growth rate (per hour) 相似文献
18.
José Miguel Müller Ranulfo Monte Alegre 《World journal of microbiology & biotechnology》2007,23(5):691-695
In this study alginate production by Pseudomonas mendocina in a laboratory-scale fermenter was investigated. In the experiments the effect of temperature (25–31°C) and agitation (500–620 rev min−1) at a constant air flow of 10 v/v/h were evaluated in relation to the rate of glucose bioconversion to alginate using response
surface methodology (RSM). The fermenter configuration was also adapted to a system with a screw mixer and draft tube, due
to the change in rheological characteristics of the fermentation broth. The adjusted model indicates a temperature of 29.1°C
and agitation of 553 rev min−1 for optimum alginate synthesis. In this fermentation system a Y
p/s
of 44.8% was achieved. The alginate synthesized by P. mendocina showed a partially acetylated pattern as previously reported for alginates obtained from other Pseudomonas spp and Azotobacter vinelandii. 相似文献
19.
F. M. Cunha A. L. G. Bacchin A. C. L. Horta T. C. Zangirolami A. C. Badino C. S. Farinas 《Biotechnology and Bioprocess Engineering》2012,17(1):100-108
A process that combines the advantages of solid state fermentation (SSF) and submerged fermentation (SmF) could increase the
efficiency of cellulase production required in the cellulosic ethanol industry. Due to the difficulty of measuring cellular
biomass in the presence of solids, we developed a novel methodology for indirect quantification of biomass during production
of the preculture for a combined fermentation process. Cultivation of Aspergillus niger was initiated as SSF using sugar cane bagasse as a solid substrate. Experiments were conducted in the absence of bagasse
to determine growth kinetic parameters. Changes in glucose and biomass concentrations were measured. and the data were used
for simulation employing a simple unstructured model. Parameters were estimated by applying a combination of Simulated Annealing
(SA) and Levenberg-Marquardt (LM) algorithms to search for minimization of the error between model estimates and experimental
data. Growth kinetics followed the Contois model, with a maximum specific growth rate (μmax) of 0.042/h, a yield coefficient for biomass formation (Yx/s) of 0.30 g/g and a death constant (kD) of 0.005/h.These parameters were used to simulate cellular growth in the solids-containing medium. The proposed model accurately
described the experimental data and succeeded in simulating the cell concentration profile. The selected pre-culture conditions
(24 h as SSF followed by 48 h as SmF) were applied for cellulase production using the combined fermentation process and resulted
in an endoglucanase activity (1,052 ± 34 U/L) greater than that obtained using the conventional SmF procedure (824 ± 44 U/L).
Besides the standardization of pre-culture conditions, this methodology could be very useful in systems where direct measurement
of cell mass is not possible. 相似文献
20.
J. P. Delgenes R. Moletta J. M. Navarro 《Applied microbiology and biotechnology》1988,29(2-3):155-161
Summary The effect of substrate concentration (S
0) on the fermentation parameters of a sugar mixture byPichia stipitis Y 7124 was investigated under anaerobic and microaerobic conditions. Under microaerobiosisP. stipitis maintained high ethanol yield and productivity when initial substrate concentration did not exceed 150 g/l; ethanol yield of about 0.40 g/g and volumetric productivity up to 0.39 g/l per hour were obtained. Optimal specific ethanol productivity (0.2 g/g per hour) was observed withS
0=110 g/l. Under anaerobic conditionsP. stipitis exhibited the highest fermentative performances atS
0=20 g/l; it produced ethanol with a yield of 0.42 g/g, with a specific rate of 1.1 g/g per day. When the initial substrate level increased, specific ethanol productivity declined gradually and ethanol yield was dependent on the degree of utilization of each sugar in the mixture.Abbreviations
E
m
maximum produced ethanol (g/l)
-
E
0
initial ethanol (g/l)
-
E
v
evaporated ethanol (g/l)
-
Q
p
volumetric productivity of ethanol (g ethanol/l per hour or g/l per day)
-
q
p
specific productivity of ethanol (g ethanol/g cells per hour)
-
q
pm
maximum specific productivity of ethanol (g/l per hour)
-
S
0
initial substrate concentration (g/l)
-
t
f
time at which produced ethanol is maximum (h)
-
Y
p/s
ethanol yield (g ethanol produced/g substrate utilized)
-
Y
x/s
cell yeild (g cells produced/g substrate utilized)
-
Y
xo/xy
xylitol yield (g xylitol produced/g xylose utilized)
-
probability coefficient
-
specific growth rate coefficient (h-1 or d-1) 相似文献