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1.
Nuno P Mira Margarida Palma Joana F Guerreiro Isabel Sá-Correia 《Microbial cell factories》2010,9(1):79
Background
Acetic acid is a byproduct of Saccharomyces cerevisiae alcoholic fermentation. Together with high concentrations of ethanol and other toxic metabolites, acetic acid may contribute to fermentation arrest and reduced ethanol productivity. This weak acid is also a present in lignocellulosic hydrolysates, a highly interesting non-feedstock substrate in industrial biotechnology. Therefore, the better understanding of the molecular mechanisms underlying S. cerevisiae tolerance to acetic acid is essential for the rational selection of optimal fermentation conditions and the engineering of more robust industrial strains to be used in processes in which yeast is explored as cell factory. 相似文献2.
Alcoholic fermentation of carbon sources in biomass hydrolysates by Saccharomyces cerevisiae: current status 总被引:1,自引:0,他引:1
van Maris AJ Abbott DA Bellissimi E van den Brink J Kuyper M Luttik MA Wisselink HW Scheffers WA van Dijken JP Pronk JT 《Antonie van Leeuwenhoek》2006,90(4):391-418
Fuel ethanol production from plant biomass hydrolysates by Saccharomyces cerevisiae is of great economic and environmental significance. This paper reviews the current status with respect to alcoholic fermentation of the main plant biomass-derived monosaccharides by this yeast. Wild-type S. cerevisiae strains readily ferment glucose, mannose and fructose via the Embden–Meyerhof pathway of glycolysis, while galactose is fermented via the Leloir pathway. Construction of yeast strains that efficiently convert other potentially fermentable substrates in plant biomass hydrolysates into ethanol is a major challenge in metabolic engineering. The most abundant of these compounds is xylose. Recent metabolic and evolutionary engineering studies on S. cerevisiae strains that express a fungal xylose isomerase have enabled the rapid and efficient␣anaerobic fermentation of this pentose. l-Arabinose fermentation, based on the expression of a prokaryotic pathway in S. cerevisiae, has also been established, but needs further optimization before it can be considered for industrial implementation. In addition to these already investigated strategies, possible approaches for metabolic engineering of galacturonic acid and rhamnose fermentation by S. cerevisiae are discussed. An emerging and major challenge is to achieve the rapid transition from proof-of-principle experiments under ‘academic’ conditions (synthetic media, single substrates or simple substrate mixtures, absence of toxic inhibitors) towards efficient conversion of complex industrial substrate mixtures that contain synergistically acting inhibitors. 相似文献
3.
An effective, simple, and convenient method to improve yeast’s multiple-stress tolerance, and ethanol production was developed.
After an ethanologenic Saccharomyces cerevisiae strain SC521 was treated by nine cycles of freeze-thaw, a mutant FT9-11 strain with higher multiple-stress tolerance was
isolated, whose viabilities under acetic acid, ethanol, freeze-thaw, H2O2, and heat-shock stresses were, respectively, 23-, 26-, 10- and 7-fold more than the parent strain at an initial value 2 × 107 c.f.u. per ml. Ethanol production of FT9-11 was similar (91.5 g ethanol l−1) to SC521 at 30°C with 200 g glucose l−1, and was better than the parent strain at 37°C (72.5 g ethanol l−1), with 300 (111 g ethanol l−1) or with 400 (85 g ethanol l−1) g glucose l−1. 相似文献
4.
Graves T Narendranath NV Dawson K Power R 《Applied microbiology and biotechnology》2007,73(5):1190-1196
The combined effects of lactic acid and acetic acid on ethanol production by S. cerevisiae in corn mash, as influenced by temperature, were examined. Duplicate full factorial experiments (three lactic acid concentrations
× three acetic acid concentrations) were performed to evaluate the interaction between lactic and acetic acids on the ethanol
production of yeast at each of the three temperatures, 30, 34, and 37°C. Corn mash at 30% dry solids adjusted to pH 4 after
lactic and acetic acid addition was used as the substrate. Ethanol production rates and final ethanol concentrations decreased
(P<0.001) progressively as the concentration of combined lactic and acetic acids in the corn mash increased and the temperature
was raised from 30 to 37°C. At 30°C, essentially no ethanol was produced after 96 h when 0.5% w/v acetic acid was present
in the mash (with 0.5, 2, and 4% w/v lactic acid). At 34 and 37°C, the final concentrations of ethanol produced by the yeast
were noticeably reduced by the presence of 0.3% w/v acetic acid and ≥2% w/v lactic acid. It can be concluded that, as in previous
studies with defined media, lactic acid and acetic acid act synergistically to reduce ethanol production by yeast in corn
mash. In addition, the inhibitory effects of combined lactic and acetic acid in corn mash were more apparent at elevated temperatures. 相似文献
5.
Rogério S. Pereira Solange I. Mussatto Inês C. Roberto 《Journal of industrial microbiology & biotechnology》2011,38(1):71-78
The inhibitory action of acetic acid, ferulic acid, and syringaldehyde on metabolism of Candida guilliermondii yeast during xylose to xylitol bioconversion was evaluated. Assays were performed in buffered and nonbuffered semidefined
medium containing xylose as main sugar (80.0 g/l), supplemented or not with acetic acid (0.8–2.6 g/l), ferulic acid (0.2–0.6 g/l),
and/or syringaldehyde (0.3–0.8 g/l), according to a 23 full factorial design. Since only individual effects of the variables were observed, assays were performed in a next step
in semidefined medium containing different concentrations of each toxic compound individually, for better understanding of
their maximum concentration that can be present in the fermentation medium without affecting yeast metabolism. It was concluded
that acetic acid, ferulic acid, and syringaldehyde are compounds that may affect Candida guilliermondii metabolism (mainly cell growth) during bioconversion of xylose to xylitol. Such results are of interest and reveal that complete
removal of toxic compounds from the fermentation medium is not necessary to obtain efficient conversion of xylose to xylitol
by Candida guilliermondii. Fermentation in buffered medium was also considered as an alternative to overcome the inhibition caused by these toxic compounds,
mainly by acetic acid. 相似文献
6.
Dae Haeng Cho Yun Jie Lee Youngsoon Um Byoung-In Sang Yong Hwan Kim 《Applied microbiology and biotechnology》2009,83(6):1035-1043
In the present study, we investigated the peroxidase-catalyzed detoxification of model phenolic compounds and evaluated the
inhibitory effects of the detoxified solution on butanol production by Clostridium beijerinckii National Collection of Industrial and Marine Bacteria Ltd. 8052. The six phenolic compounds, p-coumaric acid, ferulic acid, 4-hydroxybenzoic acid, vanillic acid, syringaldehyde, and vanillin, were selected as model fermentation
inhibitors generated during pretreatment and hydrolysis of lignocellulose. The enzyme reaction was optimized as a function
of the reaction conditions of pH, peroxidase concentration, and hydrogen peroxide to substrate ratio. Most of the tested phenolics
have a broad optimum pH range of 6.0 to 9. Removal efficiency increased with the molar ratio of H2O2 to each compound up to 0.5–1.25. In the case of p-coumaric acid, ferulic acid, vanillic acid, and vanillin, the removal efficiency was almost 100% with only 0.01 μM of enzyme.
The tested phenolic compounds (1 g/L) inhibited cell growth by 64–74%, while completely inhibiting the production of butanol. Although syringaldehyde and vanillin were less toxic on cell growth, the level of inhibition on the butanol production was
quite different. The detoxified solution remarkably improved cell growth and surprisingly increased butanol production to
the level of the control. Hence, our present study, using peroxidase for the removal of model phenolic compounds, could be
applied towards the detoxification of lignocellulosic hydrolysates for butanol fermentation. 相似文献
7.
Effect of pH and lactic or acetic acid on ethanol productivity by Saccharomyces cerevisiae in corn mash 总被引:1,自引:0,他引:1
Graves T Narendranath NV Dawson K Power R 《Journal of industrial microbiology & biotechnology》2006,33(6):469-474
The effects of lactic and acetic acids on ethanol production by Saccharomyces cerevisiae in corn mash, as influenced by pH and dissolved solids concentration, were examined. The lactic and acetic acid concentrations utilized were 0, 0.5, 1.0, 2.0, 3.0 and 4.0% w/v, and 0, 0.1, 0.2, 0.4, 0.8 and 1.6% w/v, respectively. Corn mashes (20, 25 and 30% dry solids) were adjusted to the following pH levels after lactic or acetic acid addition: 4.0, 4.5, 5.0 or 5.5 prior to yeast inoculation. Lactic acid did not completely inhibit ethanol production by the yeast. However, lactic acid at 4% w/v decreased (P<0.05) final ethanol concentration in all mashes at all pH levels. In 30% solids mash set at pH ≤5, lactic acid at 3% w/v reduced (P<0.05) ethanol production. In contrast, inhibition by acetic acid increased as the concentration of solids in the mash increased and the pH of the medium declined. Ethanol production was completely inhibited in all mashes set at pH 4 in the presence of acetic acid at concentrations ≥0.8% w/v. In 30% solids mash set at pH 4, final ethanol levels decreased (P<0.01) with only 0.1% w/v acetic acid. These results suggest that the inhibitory effects of lactic acid and acetic acid on ethanol production in corn mash fermentation when set at a pH of 5.0–5.5 are not as great as that reported thus far using laboratory media. 相似文献
8.
Xuechang Wu Lijie Zhang Xinna Jin Yahong Fang Ke Zhang Lei Qi Daoqiong Zheng 《Biotechnology letters》2016,38(7):1097-1106
9.
Yulin Lu Ryan Warner Miroslav Sedlak Nancy Ho Nathan S. Mosier 《Biotechnology progress》2009,25(2):349-356
The inhibitory effects of furfural and acetic acid on the fermentation of xylose and glucose to ethanol in YEPDX medium by a recombinant Saccharomyces cerevisiae strain (LNH‐ST 424A) were investigated. Initial furfural concentrations below 5 g/L caused negligible inhibition to glucose and xylose consumption rates in batch fermentations with high inoculum (4.5–6.0 g/L). At higher initial furfural concentrations (10–15 g/L) the inhibition became significant with xylose consumption rates especially affected. Interactive inhibition between acetic acid and pH were observed and quantified, and the results suggested the importance of conditioning the pH of hydrolysates for optimal fermentation performance. Poplar biomass pretreated by various CAFI processes (dilute acid, AFEX, ARP, SO2‐catalyzed steam explosion, and controlled‐pH) under respective optimal conditions was enzymatically hydrolyzed, and the mixed sugar streams in the hydrolysates were fermented. The 5‐hydroxymethyl furfural (HMF) and furfural concentrations were low in all hydrolysates and did not pose negative effects on fermentation. Maximum ethanol productivity showed that 0–6.2 g/L initial acetic acid does not substantially affect the ethanol fermentation with proper pH adjustment, confirming the results from rich media fermentations with reagent grade sugars. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
10.
Mark R. Wilkins Lilis Suryawati Niels O. Maness Donna Chrz 《World journal of microbiology & biotechnology》2007,23(8):1161-1168
Summary Two ethanologenic yeasts, Saccharomyces cerevisiae and Kluyveromyces marxianus, were used to ferment sugar solutions modeling hydrolyzed Valencia orange peel waste at 37°C. Orange stripper oil produced
from orange peel was added in various amounts to determine its effect on ethanol production. The minimum peel oil concentration
that inhibited ethanol production was determined after 24, 48 and 72 h and the two yeasts were compared to one another in
terms of ethanol yield. Minimum inhibitory peel oil concentrations for ethanol production were 0.05% at 24 h, 0.10% at 48 h,
and 0.15% at 72 h for both yeasts. S. cerevisiae produced more ethanol than K. marxianus at each time point. 相似文献
11.
Mendoza LM de Nadra MC Bru E Farías ME 《Journal of industrial microbiology & biotechnology》2009,36(2):229-237
The influence of two physicochemical factors involved in winemaking, temperature and SO2, on the kinetics and metabolic behavior of Kloeckera apiculata and Saccharomyces cerevisiae was examined. Highest biomass was reached at 15 and 25°C for K. apiculata and S. cerevisiae, respectively. Pure cultures of K. apiculata died off early with increasing temperature, but in co-culture with S. cerevisiae it showed higher viability and a change in the death curve from exponential to linear. Statistical analysis revealed that
metabolite production was significantly different for the three cultures and also at the different fermentation temperatures.
Besides, the interaction between culture type and temperature was significant. At temperatures from 15 to 30°C the mixed culture
showed similar ethanol and lower acetic acid production compared with a pure culture of K. apiculata. SO2 addition slightly increased survival of the non-Saccharomyces species in pure and mixed cultures. Statistical evaluation indicated that culture type and SO2 addition significantly affected metabolite production, but the interaction between culture and SO2 was not significant. These results contribute to current knowledge of enological factors and their effect on prevalence and
fermentative activities of the composite yeast flora and the statistical significance emphasizes the importance of the combined
influence of the culture type and physicochemical factors on the production of fermentation metabolites. 相似文献
12.
Aim: To examine the growth and survival of Williopsis saturnus strains along with wine yeast Saccharomyces cerevisiae in grape must. Methods and Results: For this study, fermentations were performed in sterilized grape must at 18°C. Inoculum level was 5 × 106 cells per ml for each yeast. The results showed that W. saturnus yeasts exhibited slight growth and survival depending on the strain, but they died off by day 5. Saccharomyces cerevisiae, however, dominated the fermentation, reaching the population of about 8 log CFU ml?1. It was observed that ethanol formation was not affected. The concentrations of acetic acid, ethyl acetate and isoamyl acetate were found higher in mixed culture experiments compared to control fermentation. The results also revealed that higher alcohols production was unaffected in general. Conclusion: Fermentations did not form undesirable concentrations of flavour compounds, but production of higher levels of acetic acid in mixed culture fermentations may unfavour the usage of W. saturnus in wine making. Significance and Impact of the Study: This study provides information on the behaviour of W. saturnus together with S. cerevisiae during the alcoholic fermentation. 相似文献
13.
The fermentative behavior of two hybrid wine yeast strains (first-generation hybrid-strain 12 233×6167—obtained by hybridization
of the cryotolerant strainS. bayanus 12 233 with the mesophilic strainsS. cerevisiae 6167, and TT254×6392 arising by hybridization of the thermotolerant strainS. cerevisiae TT254 with the mesophilic strainS. cerevisiae 6392) was compared with that of a commercial wine yeast strainS. cerevisiae K1 in must from black grapes of the Calabrian variety Gaglioppo. The goal was to obtain wines with a high content of ‘polyphenols’
from a grape must with a limited phenolic content such as the Gaglioppo must. The progress of the winemaking was estimated
according to residual sugars; at the end of fermentation, the wines were decanted, bottled and principal physico-chemical
characteristics determined. Our results point to the possibility to select wine yeasts (significantly differing in the above
parameters) by their ability to interact with phenolic compounds. 相似文献
14.
Lignin hydrolysates contain many different chemical species, including ferulic acid, coumaric acid, vanillic acid, vanillin, syringaldehyde and furfural. From the perspective of biofuels, these compounds are problematic and can cause downstream loss of product if not removed prior to beginning the fermentative process. In contrast, a search for these compounds within the literature turns up many papers where the same compounds have beneficial properties pertaining to human health, including as antioxidants and in cancer prevention, or are involved in bacterial cell-to-cell signaling. Consequently, this article reviews the dual nature of these and other compounds found in lignin hydrolysates, highlighting both their detrimental and beneficial activities. 相似文献
15.
《Enzyme and microbial technology》2003,32(3-4):386-395
Low-molecular weight aliphatic acids, furaldehydes and a broad range of different aromatic compounds are known to inhibit the fermentation of lignocellulose hydrolysates by yeasts. In this work, a cocktail of different lignocellulose-derived inhibitors was used to compare the inhibitor resistance of eleven different industrial and laboratory Saccharomyces cerevisiae strains and two Zygosaccharomyces strains. The inhibitor cocktail was composed of two aliphatic acids, formic and acetic acid, two furaldehydes, furfural and 5-hydroxymethylfurfural (HMF), and two aromatic compounds, cinnamic acid and coniferyl aldehyde. Fermentations were performed under oxygen-limited conditions and with different levels (100, 75, 50, 25 and 0%) of the inhibitor cocktail present. The ethanol yield on initial glucose, the volumetric and specific ethanol productivity, the biomass yield and the glucose consumption rates were used as criteria for the performance of the strains. The results revealed major differences in inhibitor resistance between yeast strains within the same species. The ethanol yield of the S. cerevisiae strain that was least affected decreased only with 10% at an inhibitor cocktail concentration of 100%, while the decrease in ethanol yield for the most sensitive S. cerevisiae strain was more than 50% already at an inhibitor cocktail concentration of 25%. Ethanol formation was generally less affected than growth and ethanol yield less than ethanol productivity. The two most resistant strains were an S. cerevisiae strain isolated from a spent sulphite liquor plant and one of the laboratory S. cerevisiae strains. Additional fermentations with either HMF or coniferyl aldehyde revealed that the degree of resistance of different yeast strains was highly dependent on the inhibitor used. A mutant strain of S. cerevisiae displaying enhanced resistance against coniferyl aldehyde compared with the parental strains was identified. 相似文献
16.
Ja Kyong Ko Tseveendorj Enkh‐Amgalan Gyeongtaek Gong Youngsoon Um Sun‐Mi Lee 《Global Change Biology Bioenergy》2020,12(1):90-100
Lignocellulosic biomass has considerable potential for the production of fuels and chemicals as a promising alternative to conventional fossil fuels. However, the bioconversion of lignocellulosic biomass to desired products must be improved to reach economic viability. One of the main technical hurdles is the presence of inhibitors in biomass hydrolysates, which hampers the bioconversion efficiency by biorefinery microbial platforms such as Saccharomyces cerevisiae in terms of both production yields and rates. In particular, acetic acid, a major inhibitor derived from lignocellulosic biomass, severely restrains the performance of engineered xylose‐utilizing S. cerevisiae strains, resulting in decreased cell growth, xylose utilization rate, and product yield. In this study, the robustness of XUSE, one of the best xylose‐utilizing strains, was improved for the efficient conversion of lignocellulosic biomass into bioethanol under the inhibitory condition of acetic acid stress. Through adaptive laboratory evolution, we successfully developed the evolved strain XUSAE57, which efficiently converted xylose to ethanol with high yields of 0.43–0.50 g ethanol/g xylose even under 2–5 g/L of acetic stress. XUSAE57 not only achieved twofold higher ethanol yields but also improved the xylose utilization rate by more than twofold compared to those of XUSE in the presence of 4 g/L of acetic acid. During fermentation of lignocellulosic hydrolysate, XUSAE57 simultaneously converted glucose and xylose with the highest ethanol yield reported to date (0.49 g ethanol/g sugars). This study demonstrates that the bioconversion of lignocellulosic biomass by an engineered strain could be significantly improved through adaptive laboratory evolution for acetate tolerance, which could help realize the development of an economically feasible lignocellulosic biorefinery to produce fuels and chemicals. 相似文献
17.
L. I. Vorob’eva E. Yu. Khodzhaev A. L. Mulyukin I. Yu. Toropygin 《Applied Biochemistry and Microbiology》2009,45(5):489-493
Reactivating factor (RF) from Luteococcus japonicus subsp. casei was shown to be constitutively synthesized and to act a by one-step mechanism, being activated independently from stress.
Cell reactivation (reversion of a cell’s ability to form macrocolonies) might be ensured by the membrane mechanism of RF action,
which is proved with the dependence of antistress activity from the condition of the cytoplasmic membrane and with the form
of concentration dependence. The incubation of UV-treated L. casei suspension with RF increased the number of cells with intact barrier membrane (1.6–1.8-fold increase compared to RF-untreated
cells) and the number of colony-forming cells. Cross defensive and reactivating RF effects on both L. casei and yeast Saccharomyces cerevisiae cells were described. Bacterial and yeast’s RF compete for membrane receptors. Matrix Assisted Laser Desorption/Ionization
time-of-flight (MALDI-TOF) spectrometry revealed that RF of L. casei contained two major peptides of 5.8 and 7.6 kDa, while RF of S. cerevisiae was represented by a single peptide of 5.8 kDa. The presence of 5.8 kDa peptide in RF from bacteria and yeasts might ensure
cross responses in these organisms. 相似文献
18.
Alice Vilela-Moura Dorit Schuller Arlete Mendes-Faia Manuela Côrte-Real 《Applied microbiology and biotechnology》2010,87(4):1317-1326
Herein, we report the influence of different combinations of initial concentration of acetic acid and ethanol on the removal
of acetic acid from acidic wines by two commercial Saccharomyces cerevisiae strains S26 and S29. Both strains reduced the volatile acidity of an acidic wine (1.0 g l−1 acetic acid and 11% (v/v) ethanol) by 78% and 48%, respectively. Acetic acid removal by strains S26 and S29 was associated with a decrease in ethanol
concentration of 0.7 and 1.2% (v/v), respectively. Strain S26 revealed better removal efficiency due to its higher tolerance to stress factors imposed by acidic
wines. Sulfur dioxide (SO2) in the concentration range 95–170 mg l−1 inhibits the ability of both strains to reduce the volatile acidity of the acidic wine used under our experimental conditions.
Therefore, deacidification should be carried out either in wines stabilized by filtration or in wines with SO2 concentrations up to 70 mg l−1. Deacidification of wines with the better performing strain S26 was associated with changes in the concentration of volatile
compounds. The most pronounced increase was observed for isoamyl acetate (banana) and ethyl hexanoate (apple, pineapple),
with an 18- and 25-fold increment, respectively, to values above the detection threshold. The acetaldehyde concentration of
the deacidified wine was 2.3 times higher, and may have a detrimental effect on the wine aroma. Moreover, deacidification
led to increased fatty acids concentration, but still within the range of values described for spontaneous fermentations,
and with apparently no negative impact on the organoleptical properties. 相似文献
19.
Galafassi S Merico A Pizza F Hellborg L Molinari F Piškur J Compagno C 《Journal of industrial microbiology & biotechnology》2011,38(8):1079-1088
Industrial fermentation of lignocellulosic hydrolysates to ethanol requires microorganisms able to utilise a broad range of
carbon sources and generate ethanol at high yield and productivity. D. bruxellensis has recently been reported to contaminate commercial ethanol processes, where it competes with Saccharomyces cerevisiae [4, 26]. In this work Brettanomyces/Dekkera yeasts were studied to explore their potential to produce ethanol from renewable sources under conditions suitable for industrial
processes, such as oxygen-limited and low-pH conditions. Over 50 strains were analysed for their ability to utilise a variety
of carbon sources, and some strains grew on cellobiose and pentoses. Two strains of D. bruxellensis were able to produce ethanol at high yield (0.44 g g−1 glucose), comparable to those reported for S. cerevisiae. B. naardenensis was shown to be able to produce ethanol from xylose. To obtain ethanol from synthetic lignocellulosic hydrolysates we developed
a two-step fermentation strategy: the first step under aerobic conditions for fast production of biomass from mixtures of
hexoses and pentoses, followed by a second step under oxygen limitation to promote ethanol production. Under these conditions
we obtained biomass and ethanol production on synthetic lignocellulosic hydrolysates, with ethanol yields ranging from 0.2
to 0.3 g g−1 sugar. Hexoses, xylose and arabinose were consumed at the end of the process, resulting in 13 g l−1 of ethanol, even in the presence of furfural. Our studies showed that Brettanomyces/Dekkera yeasts have clear potential for further development for industrial processes aimed at production of ethanol from renewable
sources. 相似文献
20.
Efficient fermentation of xylose, which is abundant in hydrolysates of lignocellulosic biomass, is essential for producing
cellulosic biofuels economically. While heterologous expression of xylose isomerase in Saccharomyces cerevisiae has been proposed as a strategy to engineer this yeast for xylose fermentation, only a few xylose isomerase genes from fungi
and bacteria have been functionally expressed in S. cerevisiae. We cloned two bacterial xylose isomerase genes from anaerobic bacteria (Bacteroides stercoris HJ-15 and Bifidobacterium longum MG1) and introduced them into S. cerevisiae. While the transformant with xylA from B. longum could not assimilate xylose, the transformant with xylA from B. stercoris was able to grow on xylose. This result suggests that the xylose isomerase (BsXI) from B. stercoris is functionally expressed in S. cerevisiae. The engineered S. cerevisiae strain with BsXI consumed xylose and produced ethanol with a good yield (0.31 g/g) under anaerobic conditions. Interestingly, significant
amounts of xylitol (0.23 g xylitol/g xylose) were still accumulated during xylose fermentation even though the introduced
BsXI might not cause redox imbalance. We investigated the potential inhibitory effects of the accumulated xylitol on xylose fermentation.
Although xylitol inhibited in vitro BsXI activity significantly (K
I = 5.1 ± 1.15 mM), only small decreases (less than 10%) in xylose consumption and ethanol production rates were observed when
xylitol was added into the fermentation medium. These results suggest that xylitol accumulation does not inhibit xylose fermentation
by engineered S. cerevisiae expressing xylA as severely as it inhibits the xylose isomerase reaction in vitro. 相似文献