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1.
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
2.
Inhibition of microbial xylitol production by acetic acid and its relation with fermentative parameters 总被引:5,自引:0,他引:5
Precipitated sugarcane bagasse hemicellulosic hydrolysate containing acetic acid was fermented by Candida guilliermondii FTI 20037 under different operational conditions (pH 4.0 and 7.0, three aeration rates). At pH 7.0 and k
L
a of 10 (0.75 vvm) and 22.5/h (3.0 vvm) the acetic acid had not been consumed until the end of the fermentations, whereas at
the same pH and k
L
a of 35/h (4.5 vvm) the acid was rapidly consumed and acetic acid inhibition was not important. On the other hand, fermentations
at an initial pH of 4.0 and k
L
a of 22.5 and 35/h required less time for the acid uptake than fermentations at k
L
a of 10/h. The acetic acid assimilation by the yeast indicates the ability of this strain to ferment in partially detoxified
medium, making possible the utilization of the sugarcane bagasse hydrolysate in this bioprocess. The effects on xylitol yield
and production are reported. 相似文献
3.
Efficient utilization of the pentosan fraction of hemicellulose from lignocellulosic feedstocks offers an opportunity to increase
the yield and to reduce the cost of producing fuel ethanol. During prehydrolysis (acid hydrolysis or autohydrolysis of hemicellulose),
acetic acid is formed as a consequence of the deacetylation of the acetylated moiety of hemicellulose. Recombinant Escherichia
coli B (ATCC 11303), carrying the plasmid pLO1297 with pyruvate decarboxylase and alcohol dehydrogenase II genes from Zymomonas
mobilis (CP4), converts xylose to ethanol with a product yield that approaches theoretical maximum. Although other pentose-utilizing
microorganisms are inhibited by acetic acid, the recombinant E. coli displays a high tolerance for acetic acid. In xylose
fermentations with a synthetic medium (Luria broth), where the pH was controlled at 7, neither yield nor productivity was
affected by the addition of 10.7 g/L acetic acid. Nutrient-supplemented, hardwood (aspen) hemicellulose hydrolysate (40.7
g/L xylose) was completely fermented to ethanol (16.3 g/L) in 98 h. When the acetic acid concentration was reduced from 5.6
to 0.8 g/L, the fermentation time decreased to 58 h. Overliming, with Ca(OH)2 to pH 10, followed by neutralization to pH 7 with sulfuric acid and removal of insolubles, resulted in a twofold increase
in volumetric productivity. The maximum productivity was 0.93 g/L/h. The xylose-to-ethanol conversion efficiency and productivity
in Ca(OH)2-treated hardwood prehydrolysate, fortified with only mineral salts, were 94% and 0.26 g/L/h, respectively. The recombinant
E. coli exhibits a xylose-to-ethanol conversion efficiency that is superior to that of other pentose-utilizing yeasts currently
being investigated for the production of fuel ethanol from lignocellulosic materials. 相似文献
4.
Lawford Hugh G. Rousseau Joyce D. McMillan James D. 《Applied biochemistry and biotechnology》1997,(1):269-286
The five-carbon sugard-xylose is a major component of hemicellulose and accounts for roughly one-third of the carbohydrate content of many lignocellulosic
materials. The efficient fermentation of xylose-rich hemicellulose hydrolyzates (prehydrolyzates) represents an opportunity
to improve significantly the economics of large-scale fuel ethanol production from lignocellulosic feedstocks. The National
Renewable Energy Laboratory (NREL) is currently investigating a simultaneous saccharification and cofermentation (SSCF) process
for ethanol production from biomass that uses a dilute-acid pretreatment and a metabolically engineered strain ofZymomonas mobilis that can coferment glucose and xylose. The objective of this study was to establish optimal conditions for cost-effective
seed production that are compatible with the SSCF process design.
Two-level and three-level full factorial experimental designs were employed to characterize efficiently the growth performance
of recombinantZ. mobilis CP4:pZB5 as a function of nutrient level, pH, and acetic acid concentration using a synthetic hardwood hemicellulose hydrolyzate
containing 4% (w/v) xylose and 0.8% (w/v) glucose. Fermentations were run batchwise and were pH-controlled at low levels of
clarified corn steep liquor (cCSL, 1-2% v/v), which were used as the sole source of nutrients. For the purpose of assessing
comparative fermentation performance, seed production was also carried out using a “benchmark” yeast extract-based laboratory
medium. Analysis of variance (ANOVA) of experimental results was performed to determine the main effects and possible interactive
effects of nutrient (cCSL) level, pH, and acetic acid concentration on the rate of xylose utilization and the extent of cell
mass production. Results indicate that the concentration of acetic acid is the most significant limiting factor for the xylose
utilization rate and the extent of cell mass production; nutrient level and pH exerted weaker, but statistically significant
effects. At pH 6.0, in the absence of acetic acid, the final cell mass concentration was 1.4 g dry cell mass/L (g DCM/L),
but decreased to 0.92 and 0.64 g DCM/L in the presence of 0.5 and 1.0% (w/v) acetic acid, respectively. At concentrations
of acetic acid of 0.75 (w/v) or lower, fermentation was complete within 1.5 d. In contrast, in the presence of 1.0% (w/v)
acetic acid, 25% of the xylose remained after 2 d. At a volumetric supplementation level of 1.5–2.0% (v/v), cCSL proved to
be a cost-effective single-source nutritional adjunct that can support growth and fermentation performance at levels comparable
to those achieved using the expensive yeast extract-based laboratory reference medium. 相似文献
5.
The structure and the biosorption properties of fungal biomass of Aspergillus niger originated from citric acid fermentation industry was investigated. This waste biomass, produced in high quantity in carefully
controlled industrial processes, has certain favourable characteristics that may be improved for its usefulness. In environmental
chemistry, it is known for the removal of heavy metals cations. In this work, different alkaline treatments (1M NaOH/20°C/24
h and 10M NaOH/107°C/6 h) were used to evaluate the dependence of sorption properties of biomass on the cell wall composition.
The biosorption was studied by the batch method, with the biomass concentration of 1 g/l, at pH 6. The adsorption of lead
was more effective than that of cadmium. The biosorption capacity was evaluated using the biosorption isotherm derived from
the equilibrium data. At pH 6, the maximmum lead biosorption capacity estimated with the Langmuir model was 93 mg/g dry biomass. 相似文献
6.
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
7.
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
8.
An unusual continuous film formation process of lateral pentyloxy substituted poly(p-phenylene terephthalate)s (s-PPPT) and poly(carbonate) (PC) is observed. A liquid film of polymer solution creeps over the surface of water dropped into the polymer solution. By vaporization of the solvent a solid polymer film is formed on the water surface and can be removed. The driving force for the film formation mechanism is assumed by the reduction of the surface tension of water. Experiments verify this mechanism by increasing the film formation speed using a gas stream, by reducing the formation speed through lowering the surface tension by rinsing agents, and by lowering the solubility of the polymer. As expected, no effects are found by variation of the pH-value of water. Necessary conditions for the film formation process are: good solubility of the polar polymers in organic solvents having a high vapor pressure, complete phase separation, solution density higher than water density, and a surrounding gas phase unsaturated with solvent vapor.The thickness of the mechanically stable films is less than 0.5 m. The films are amorphous by microscopical, FT-IR, x-ray, and DTA investigations. 相似文献
9.
Donnelly Mark I. Millard Cynthia Sanville Clark David P. Chen Michael J. Rathke Jerome W. 《Applied biochemistry and biotechnology》1998,(1):187-198
Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate:
formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored
its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor,
strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol
in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1
mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence
in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway. 相似文献
10.
Jin-Nam Kim Jong-Sok Choo Young-Jung Wee Jong-Sun Yun Hwa-Won Ryu 《Applied biochemistry and biotechnology》2005,123(1-3):861-869
A new acetic acid-producing microorganism, Acetobacter sp. RKY4, was isolated from Korean traditional persimmon vinegar, and we optimized the culture medium for acetic acid production
from ethanol using the newly isolated Acetobacter sp. RKY4. The optimized culture medium for acetic acid production using this microorganism was found to be 40 g/L ethanol,
10 g/L glycerol, 10 g/L corn steep liquor, 0.5 g/L MgSO4·7H2O, and 1.0 g/L (NH4H2PO4. Acetobacter sp. RKY4 produced 47.1 g/L of acetic acid after 48 h of fermentation in a 250 mL Erlenmeyer flask containing 50 mL of the
optimized medium. 相似文献
11.
The kinetics of reaction between cyclohexanone (0.05 mol) ando-cresol (0.1 mol) in the presence of varying mixtures of hydrochloric acid and acetic acid (2:1 V/V) were determined at four
different temperatures: 40°, 50°, 60° and 70°C. The product was purified from benzene and methanol (m.p. 186°). The optimum
reaction temperature, catalyst concentration and time have been determined for obtaining yields greater than 80%. 相似文献
12.
Bi2Al4O9 ceramics are difficult to sinter to greater than 80% theoretical density due to peritectic decomposition at 1,070 °C. A novel processing method is discussed where a high-bismuth oxide-based liquid is used as a sintering aid. After sintering, the high bismuth oxide phase is removed by leaching with 40% acetic acid. The resulting samples are phase pure and ∼91% dense. The grain size varies in a wide range with the average grain size of ∼1 μm. The electrical properties of these ceramics were measured as functions of temperature (550–850 °C) and oxygen partial pressure (6×10−6–1 atm). The total conductivity was separated into electronic and ionic contributions. The low ionic conductivity indicates that the material is not an ‘intrinsically defective fast ion conductor’. The ionic conductivity is due almost exclusively to compensating oxygen vacancies related to impurities. With increasing temperature and decreasing oxygen partial pressure, the electronic conduction dominates over the ionic conduction. 相似文献
13.
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
14.
Physico-chemical properties of Chitosan films 总被引:1,自引:0,他引:1
Luminita Balau Gabriela Lisa M. I. Popa V. Tura V. Melnig 《Central European Journal of Chemistry》2004,2(4):638-647
Chitosan films obtained by dry phase inversion were prepared from an aqueous solution of chitosan in acetic acid. The films,
of thickness less than 20 μm, were transparent, very flexible and had smooth surfaces. Increasing the film thickness induced
an increase of the internal tensions and the consequent formation of a rough surface. Structural investigations by X-ray diffraction
and Fourier transform IR analysis, showed that the chitosan films, as prepared, are amorphous. Further annealing to evaporate
acetic acid and water traces, changed the amorphous phase into a more ordered phase, characterized by diffraction peaks at
2θ values of 9, 17, 20 and 23 degrees. Thermal investigations by TG, DTG, and DTA revealed that the decomposition of the chitosan
films as prepared proceeds in two stages, starting from 180°C and 540°C. 相似文献
15.
A method for the analysis of six alkyl organoiodides (iodomethane, iodoethane, 1-iodopropane, 1-iodobutane, 1-iodopentane, 1-iodohexane) commonly found in acetic acid process was developed. In this method the target analytes were determined by high-performance liquid chromatography (HPLC) using a post-column photochemical reactor with electrochemical detection (ED) in less than 30 min. HPLC was performed in ODS C18 reversed-phase column (5 microm, 250 x 4.6 mm I.D.) under isocratic conditions with methanol-0.067 M acetate buffer (70:30, v/v), pH 6.2 as mobile phase at flow-rate 1.1 ml/min. Alkyl organoiodides, which are electrochemically inactive, were made oxidizable at potential of 120 mV after post-column irradiation with low-pressure mercury lamp in a knitted PTFE tube. The photoreactor was placedin an aluminum housing full of nitrogen in order to prevent from the interference of oxygen. The detection limit for most analytes was of the order of 1-2 microg/l. The HPLC-ED method with a post-column photochemical reactor has good precision and linearity and can be readily applied to the routine determination of alkyl organoiodides in real acetic acid samples. 相似文献
16.
Xuning Zhuang Yingying Ye Wenzhi He Guangming Li Juwen Huang Shangming Lu 《Research on Chemical Intermediates》2013,39(6):2495-2504
Because of the large quantity of liquid crystal displays (LCDs) in use, the volume of waste LCDs is ever-increasing, causing growing concern about their effective treatment. Polarizers are among the most important functional films used in LCDs and are mainly treated by incineration after being discarded. In this study, they were used to produce acetic acid under the hydrothermal conditions; this could aid development of a new environmentally sustainable process for treatment of waste polarizers. The experiment was performed in a 5.7-ml bath reactor heated by use of a salt-bath. The liquid product was analyzed by high-performance liquid chromatography. The effect of reaction temperature, reaction time, and oxidant on acetic acid production was investigated. Results showed that the yield and selectivity for acetic acid initially increased with increasing reaction temperature, reaction time, and H2O2 supply but then decreased within the ranges of the experiments performed. The highest acetic acid yield of 33.4 %, with selectivity of 26.7 % based on carbon, was obtained by hydrothermal treatment of waste polarizer at 350 °C for 5 min with 0.6 ml H2O2. 相似文献
17.
Lawford Hugh G. Rousseau Joyce D. Mohagheghi Ali McMillan James D. 《Applied biochemistry and biotechnology》2000,84(1-9):295-310
This study examined the continuous cofermentation performance characteristics of a dilute-acid “prehydrolysate-adapted” recombinant
Zymomonas 39676:pZB4L and builds on the pH-stat batch fermentations with this recombinant that we reported on last year. Substitution
of yeast extract by 1% (w/v) corn steep liquor (CSL) (50% solids) and Mg (2 mM) did not alter the coferm entation performance.
Using declared assumptions, the cost of using CSL and Mg was estimated to be 12.5c/gal of ethanol with a possibility of 50%
cost reduction using fourfold less CSL with 0.1% diammonium phosphate. Because of competition for a common sugar transporter
that exhibits a higher affinity for glucose, utilization of glucose was complete whereas xylose was always present in the
chemostat effluent. The ethanol yield, based on sugar used, was 94% of theoretical maximum. Altering the sugar ratio of the
synthetic dilute acid hardwood prehydrolysate did not appear to significantly change the pattern of xylose utilization. Using
a criterion of 80% sugar utilization for determining the maximum dilution rate (D
max), changing the composition of the feed from 4% xylose to 3%, and simultaneously increasing the glucose from 0.8 to 1.8% shifted
D
max from 0.07 to 0.08/h. With equal amounts of both sugars (2.5%), D
max was 0.07/h. By comparison to a similar investigation with rec Zm CP4:pZB5 with a 4% equal mixture of xylose and glucose,
we observed that at pH 5.0, the D
max was 0.064/h and shifted to 0.084/h at pH 5.75. At a level of 0.4% (w/v) acetic acid in the CSL-based medium with 3% xylose
and 1.8% glucose at pH 5.75, the D
max for the adapted recombinant shifted from 0.08 to 0.048/h, and the corresponding maximum volumetric ethanol productivity decreased
45%, from 1.52 to 0.84 g/(L·h). Under these conditions of continuous culture, linear regression of a Pirt plot of the specific
rate of sugar utilization vs D showed that 4 g/L of acetic acid did not affect the maximum growth yield (0.030 g dry cell mass/g sugar), but did increase
the maintenance coefficient twofold, from 0.46 to 1.0 g of sugar/(g of cell·h). 相似文献
18.
Chiang Heien-Kun Foutch Gary L. Fish Wayne W. 《Applied biochemistry and biotechnology》1991,(1):513-525
Acetaldehyde has been produced biologically using whole-cellPichia pastoris in a semibatch fermentor. Ethanol and air were fed continuously, and the product, acetaldehyde, was removed by the air stream.
Operation of the reactor exceeded 100 h, maintaining high alcohol oxidase activity. Low cell-mass concentration (9.9 g/L)
minimized product inhibition. Ethanol concentration in the broth, oxygen concentration in the air, and pH were evaluated for
their effects on the fermentation process. 相似文献
19.
Kwang Il Kim Woo Kyung Kim Deok Ki Seo In Sang Yoo Eun Ki Kim Hyon Hee Yoon 《Applied biochemistry and biotechnology》2003,107(1-3):637-647
Conversion of food wastes into lactic acid by simultaneous saccharification and fermentation (SSF) was investigated. The process
involves saccharification of the starch component in food wastes by a commercial amylolytic enzyme preparation (a mixture
of amyloglucosidase, α-amylase, and protease) and fermentation by Lactobacillus delbrueckii. The highest observed overall yield of lactic acid in the SSF was 91% of theoretical. Lactic acid concentration as high as
80 g/L was attainable in 48 h of the SSF. The optimum operating conditions for the maximum productivity were found to be 42°C
and pH 6.0. Without supplementation of nitrogen-containing nutrients, the lactic acid yield in the SSF decreased to 60%: 27
g/L of lactic acid from 60 g/L of food waste. The overall performance of the SSF, however, was not significantly affected
by the elimination of mineral supplements. 相似文献
20.
Hugh G. Lawford Joyce D. Rousseau Ali Mohagheghi James D. McMillan 《Applied biochemistry and biotechnology》1999,77(1-3):191-204
Long-term (149 d) continuous fermentation was used to adapt a xylose-fermenting recombinant Zymomonas mobilis, strain 39676:pZB 4L, to conditioned (overlimed) dilute-acid yellow poplar hemicellulose hydrolyzate (“prehydrolyzate”).
An “adapted” variant was isolated from a chemostat operating at a dilution rate of 0.03/h with a 50% (v/v) prehydrolyzate,
corn steep liquor, and sugar-supplemented medium, at pH 5.75. The level of xylose and glucose in the medium was kept constant
at 4% (w/v) and 0.8% (w/v), respectively. These sugar concentrations reflect the composition of the undiluted hardwood prehydrolyzate.
The level of conditioned hardwood prehydrolyzate added to the medium was increased in 5% increments startingata level of 10%.
At the upper level of 50% prehydrolyzate, the acetic-acid concentration was about 0.75% (w/v). The adapted variant exhibited
improved xylose-fermentation performance in a pure-sugar, synthetic hardwood prehydrolyzate medium containing 4% xylose (w/v),
0.8% (w/v) glucose, and acetic acid in the range 0.4–1.0% (w/v). The ethanol yield was 0.48–0.50 g/g; equivalent to a sugar-to-ethanol
conversion efficiency of 94–96% of theoretical maximum. The maximum growth yield and maintenance energy coefficients were
0.033 g dry cell mass (DCM)/g sugars and 0.41 g sugars/g DCM/h, respectively. The results confirm that long-term continuous
adaptation is a useful technique for effecting strain improvement with respect to the fermentation of recalcitrant feedstocks. 相似文献