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1.
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
2.
Blomqvist J South E Tiukova I Tiukova L Momeni MH Hansson H Ståhlberg J Horn SJ Schnürer J Passoth V 《Letters in applied microbiology》2011,53(1):73-78
Aim: Testing the ability of the alternative ethanol production yeast Dekkera bruxellensis to produce ethanol from lignocellulose hydrolysate and comparing it to Saccharomyces cerevisiae. Methods and Results: Industrial isolates of D. bruxellensis and S. cerevisiae were cultivated in small‐scale batch fermentations of enzymatically hydrolysed steam exploded aspen sawdust. Different dilutions of hydrolysate were tested. None of the yeasts grew in undiluted or 1 : 2 diluted hydrolysate [final glucose concentration always adjusted to 40 g l?1 (0·22 mol l?1)]. This was most likely due to the presence of inhibitors such as acetate or furfural. In 1 : 5 hydrolysate, S. cerevisiae grew, but not D. bruxellensis, and in 1 : 10 hydrolysate, both yeasts grew. An external vitamin source (e.g. yeast extract) was essential for growth of D. bruxellensis in this lignocellulosic hydrolysate and strongly stimulated S. cerevisiae growth and ethanol production. Ethanol yields of 0·42 ± 0·01 g ethanol (g glucose)?1 were observed for both yeasts in 1 : 10 hydrolysate. In small‐scale continuous cultures with cell recirculation, with a gradual increase in the hydrolysate concentration, D. bruxellensis was able to grow in 1 : 5 hydrolysate. In bioreactor experiments with cell recirculation, hydrolysate contents were increased up to 1 : 2 hydrolysate, without significant losses in ethanol yields for both yeasts and only slight differences in viable cell counts, indicating an ability of both yeasts to adapt to toxic compounds in the hydrolysate. Conclusions: Dekkera bruxellensis and S. cerevisiae have a similar potential to ferment lignocellulose hydrolysate to ethanol and to adapt to fermentation inhibitors in the hydrolysate. Significance and Impact of the study: This is the first study investigating the potential of D. bruxellensis to ferment lignocellulosic hydrolysate. Its high competitiveness in industrial fermentations makes D. bruxellensis an interesting alternative for ethanol production from those substrates. 相似文献
3.
Xylulose fermentation by mutant and wild-type strains of Zygosaccharomyces and Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
Eliasson A Boles E Johansson B Osterberg M Thevelein JM Spencer-Martins I Juhnke H Hahn-Hägerdal B 《Applied microbiology and biotechnology》2000,53(4):376-382
Anaerobic xylulose fermentation was compared in strains of Zygosaccharomyces and Saccharomyces cerevisiae, mutants and wild-type strains to identify host-strain background and genetic modifications beneficial to xylose fermentation.
Overexpression of the gene (XKS1) for the pentose phosphate pathway (PPP) enzyme xylulokinase (XK) increased the ethanol yield by almost 85% and resulted
in ethanol yields [0.61 C-mmol (C-mmol consumed xylulose)−1] that were close to the theoretical yield [0.67 C-mmol (C-mmol consumed xylulose)−1]. Likewise, deletion of gluconate 6-phosphate dehydrogenase (gnd1Δ) in the PPP and deletion of trehalose 6-phosphate synthase (tps1Δ) together with trehalose 6-phosphate phosphatase (tps2Δ) increased the ethanol yield by 30% and 20%, respectively. Strains deleted in the promoter of the phosphoglucose isomerase
gene (PGI1) – resulting in reduced enzyme activities – increased the ethanol yield by 15%. Deletion of ribulose 5-phosphate (rpe1Δ) in the PPP abolished ethanol formation completely. Among non-transformed and parental strains S. cerevisiae ENY. WA-1A exhibited the highest ethanol yield, 0.47 C-mmol (C-mmol consumed xylulose)−1. Other non-transformed strains produced mainly arabinitol or xylitol from xylulose under anaerobic conditions. Contrary to
previous reports S. cerevisiae T23D and CBS 8066 were not isogenic with respect to pentose metabolism. Whereas, CBS 8066 has been reported to have a high
ethanol yield on xylulose, 0.46 C-mmol (C-mmol consumed xylulose)−1 (Yu et al. 1995), T23D only formed ethanol with a yield of 0.24 C-mmol (C-mmol consumed xylulose)−1. Strains producing arabinitol did not produce xylitol and vice versa. However, overexpression of XKS1 shifted polyol formation from xylitol to arabinitol.
Received: 2 July 1999 / Accepted in revised form: 12 October 1999 相似文献
4.
S H de Kock J C du Preez S G Kilian 《Journal of industrial microbiology & biotechnology》2000,24(4):231-236
Aerobic glucose-limited chemostat cultivations were conducted with Saccharomyces cerevisiae strains NRRL Y132, ATCC 4126 and CBS 8066, using a complex medium. At low dilution rates all three strains utilised glucose
oxidatively with high biomass yield coefficients, no ethanol production and very low steady-state residual glucose concentrations
in the culture. Above a threshold dilution rate, respiro-fermentative (oxido-reductive) metabolism commenced, with simultaneous
respiration and fermentation occurring, which is typical of Crabtree-positive yeasts. However, at high dilution rates the
three strains responded differently. At high dilution rates S. cerevisiae CBS 8066 produced 7–8 g ethanol L−1 from 20 g glucose L−1 with concomitant low levels of residual glucose, which increased markedly only close to the wash-out dilution rate. By contrast,
in the respiro-fermentative region both S. cerevisiae ATCC 4126 and NRRL Y132 produced much lower levels of ethanol (3–4 g L−1) than S. cerevisiae CBS 8066, concomitant with very high residual sugar concentrations, which was a significant deviation from Monod kinetics
and appeared to be associated either with high growth rates or with a fermentative (or respiro-fermentative) metabolism. Supplementation
of the cultures with inorganic or organic nutrients failed to improve ethanol production or glucose assimilation. Journal of Industrial Microbiology & Biotechnology (2000) 24, 231–236.
Received 09 August 1999/ Accepted in revised form 18 December 1999 相似文献
5.
Anjali Madhavan Sriappareddy Tamalampudi Aradhana Srivastava Hideki Fukuda Virendra S. Bisaria Akihiko Kondo 《Applied microbiology and biotechnology》2009,82(6):1037-1047
Previously, a Saccharomyces cerevisiae strain was engineered for xylose assimilation by the constitutive overexpression of the Orpinomyces xylose isomerase, the S. cerevisiae xylulokinase, and the Pichia stipitis SUT1 sugar transporter genes. The recombinant strain exhibited growth on xylose, under aerobic conditions, with a specific growth
rate of 0.025 h−1, while ethanol production from xylose was achieved anaerobically. In the present study, the developed recombinant yeast was
adapted for enhanced growth on xylose by serial transfer in xylose-containing minimal medium under aerobic conditions. After
repeated batch cultivations, a strain was isolated which grew with a specific growth rate of 0.133 h−1. The adapted strain could ferment 20 g l−1 of xylose to ethanol with a yield of 0.37 g g−1 and production rate of 0.026 g l−1 h−1. Raising the fermentation temperature from 30°C to 35°C resulted in a substantial increase in the ethanol yield (0.43 g g−1) and production rate (0.07 g l−1 h−1) as well as a significant reduction in the xylitol yield. By the addition of a sugar complexing agent, such as sodium tetraborate,
significant improvement in ethanol production and reduction in xylitol accumulation was achieved. Furthermore, ethanol production
from xylose and a mixture of glucose and xylose was also demonstrated in complex medium containing yeast extract, peptone,
and borate with a considerably high yield of 0.48 g g−1. 相似文献
6.
The ability of acetaldehyde (90 mg l−1) to stimulate ethanol-stressed S. cerevisiae fermentations is examined and reasons for the effect explored. Alternative metabolic electron acceptors generated similar
stimulatory effects to acetaldehyde, decreasing the ethanol-induced growth lag phase from 9 h to 3 h, suggesting a redox-driven
effect. The exposure to ethanol caused an instant 60% decline in intracellular NAD+ which was largely prevented by the addition of acetaldehyde. Furthermore, the exposure to ethanol affected glycolysis by
decreasing the rate of glucose utilisation from 0.33 g glucose g−1 biomass h−1 to 0.11 g glucose g−1 biomass h−1, while the addition of acetaldehyde to an ethanol stressed culture increased this rate to 0.14 g glucose g−1 biomass h−1. 相似文献
7.
M T Smith D R Cameron S J B Duff 《Journal of industrial microbiology & biotechnology》1997,18(1):18-21
Ethanol production from spent sulphite pulping liquor (SSL) was compared for four different yeasts. A second strain of S. cerevisiae as well as a 2-deoxyglucose-resistant strain formed through protoplast fusions between S. uvarum and S. diastaticus produced up to 27% more ethanol from SSL fortified with hydrolysis sugars than was produced by S. cerevisiae. The incremental improvement in ethanol yield appeared to vary with the degree of fortification, ranging from 5.8% for unfortified
SSL, to 27% for the highest level of fortification tested. Decreasing fermentation rates were observed for SSL fortified
with glucose, mannose and galactose, respectively. Sugar uptake rates in SSL fortified with glucose, galactose and mannose
were 6.8, 2.8 and 2.0 g L−1 h−1, respectively. However, when these sugars were fermented along with a glucose cosubstrate, the rate at which the combined
glucose/mannose medium was fermented was nearly identical to that of the glucose control.
Received 18 April 1996/ Accepted in revised form 27 August 1996 相似文献
8.
de Barros Pita W Leite FC de Souza Liberal AT Simões DA de Morais MA 《Antonie van Leeuwenhoek》2011,100(1):99-107
The yeast Dekkera bruxellensis has been regarded as a contamination problem in industrial ethanol production because it can replace the originally inoculated
Saccharomyces cerevisiae strains. The present study deals with the influence of nitrate on the relative competitiveness of D. bruxellensis and S. cerevisiae in sugar cane ethanol fermentations. The industrial strain D. bruxellensis GDB 248 showed higher growth rates than S. cerevisiae JP1 strain in mixed ammonia/nitrate media, and nitrate assimilation genes were only slightly repressed by ammonia. These
characteristics rendered D. bruxellensis cells with an ability to overcome S. cerevisiae populations in both synthetic medium and in sugar cane juice. The results were corroborated by data from industrial fermentations
that showed a correlation between high nitrate concentrations and high D. bruxellensis cell counts. Moreover, the presence of nitrate increased fermentation efficiency of D. bruxellensis cells in anaerobic conditions, which may explain the maintenance of ethanol production in the presence of D. bruxellensis in industrial processes. The presence of high levels of nitrate in sugar cane juice may be due to its inefficient conversion
by plant metabolism in certain soil types and could explain the periodical episodes of D. bruxellensis colonization of Brazilian ethanol plants. 相似文献
9.
L. Zhang Z. -P. Guo Z. -Y. Ding Z. -X. Wang G. -Y. Shi 《Applied Biochemistry and Microbiology》2012,48(2):216-221
The gene mel1, encoding α-galactosidase in Schizosaccharomyces pombe, and the gene bgl2, encoding and α-glucosidase in Trichoderma reesei, were isolated and co-expressed in the industrial ethanolproducing strain of Saccharomyces cerevisiae. The resulting strains were able to grow on cellobiose and melibiose through simultaneous production of sufficient extracellular
α-galactosidase and β-glucosidase activity. Under aerobic conditions, the growth rate of the recombinant strain GC1 co-expressing
2 genes could achieve 0.29 OD600 h−1 and a biomass yield up to 7.8 g l−1 dry cell weight on medium containing 10.0 g l−1 cellobiose and 10.0 g l−1 melibiose as sole carbohydrate source. Meanwhile, the new strain of S. cerevisiae CG1 demonstrated the ability to directly produce ethanol from microcrystalline cellulose during simultaneous saccharification
and fermentation process. Approximately 36.5 g l−1 ethanol was produced from 100 g of cellulose supplied with 5 g l−1 melibose within 60 h. The yield (g of ethanol produced/g of carbohydrate consumed) was 0.44 g/g, which corresponds to 88.0%
of the theoretical yield. 相似文献
10.
Viable Saccharomyces cerevisiae and Candida shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed
in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied
to the continuous alcoholic fermentation of a mixture of glucose (35 g dm−3) and xylose (15 g dm−3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars
was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h−1) with an excess of C. shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm−3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars−1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h−1 dm−3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution
of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased
from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.
Received: 26 February 1998 / Received revision: 15 April 1998 / Accepted: 19 April 1998 相似文献
11.
Claudio R. Zastrow Marcelo A. Mattos Claudia Hollatz Boris U. Stambuk 《Biotechnology letters》2000,22(6):455-459
Saccharomyces cerevisiae grew slower but reached higher cellular densities when grown on 20 g maltotriose l–1 than on the same concentration of glucose or maltose. Antimycin A (3 mg l–1) prevented growth on maltotriose, but not on glucose or maltose, indicating that it is not fermented but is degraded aerobically. This was confirmed by the absence of ethanol and glycerol production. Active uptake of maltotriose across the plasma membrane is the limiting step for metabolism, and the low rate of maltotriose transport observed in maltotriose-grown cells is probably one of the main reasons for the absence of maltotriose fermentation by S. cerevisiae cells. 相似文献
12.
The Aspergillus niger strain BO-1 was grown in batch, continuous (chemostat) and fed-batch cultivations in order to study the production of the
extracellular enzyme glucoamylase under different growth conditions. In the pH range 2.5–6.0, the specific glucoamylase productivity
and the specific growth rate of the fungus were independent of pH when grown in batch cultivations. The specific glucoamylase
producivity increased linearly with the specific growth rate in the range 0–0.1 h−1 and was constant in the range 0.1–0.2 h−1. Maltose and maltodextrin were non-inducing carbon sources compared to glucose, and the maximum specific growth rate was
0.19 ± 0.02 h−1 irrespective of whether glucose or maltose was the carbon source. In fed-batch cultivations, glucoamylase titres of up to
6.5 g l−1 were obtained even though the strain contained only one copy of the glaA gene.
Received: 5 May 1999 / Received revision: 7 September 1999 / Accepted: 17 September 1999 相似文献
13.
Acetobacter aceti have been grown on ethanol under inhibitory conditions created by high concentrations of phenol. A defined medium with no
vitamin or amino acid supplements has been used such that ethanol was the sole carbon substrate. The culture temperature was
maintained at 30 °C while the pH was manually controlled to fall within the range 4.5–6.0 during ethanol consumption. Growth
on ethanol at a few thousand milligrams per litre (below the known inhibitory level) resulted in a maximum specific growth
rate of 0.16 h−1 with a 95% yield of acetic acid, followed immediately by acetic acid consumption at a growth rate of 0.037 h−1. Phenol was found to inhibit growth by decreasing both the specific growth rate and the biomass yield during ethanol consumption.
On the other hand, the yield of acetic acid during ethanol consumption and the yield of biomass during acetic acid consumption
remained constant, independent of phenol inhibition. A model is presented and is shown to represent the phenol-inhibited growth
behaviour of A. aceti during both ethanol and acetic acid consumption.
Received: 6 November 1998 / Received revision: 8 February 1999 / Accepted: 12 February 1999 相似文献
14.
H. E. M. Mc Mahon C. T. Kelly W. M. Fogarty 《Applied microbiology and biotechnology》1997,48(4):504-509
The α-amylase of Streptomyces sp. IMD 2679 was subject to catabolite repression. Four different growth rates were achieved when the organism was grown
at 40 °C and 55 °C in the presence and absence of cobalt, with an inverse relationship between α-amylase production and growth
rate. Highest α-amylase yields (520 units/ml) were obtained at the lowest growth rate (0.062 h−1), at 40 °C in the absence of cobalt, while at the highest growth rate (0.35 h−1), at 55 °C in the presence of cobalt, α-amylase production was decreased to 150 units/ml. As growth rate increased, the rate
of specific utilisation of the carbon source maltose also increased, from 46 to 123 μg maltose (mg biomass)−1 h−1. The pattern and levels of α-glucosidase (the enzyme degrading maltose) detected intracellularly in each case, indicate that
growth rate effectively controls the rate of feeding of glucose to the cell, and thus catabolite repression.
Received: 17 February 1997 / Received revision: 29 April 1997 / Accepted: 11 May 1997 相似文献
15.
Francisco B. Pereira Pedro M. R. Guimarães José A. Teixeira Lucília Domingues 《Biotechnology letters》2010,32(11):1655-1661
An optimized very high gravity (VHG) glucose medium supplemented with low cost nutrient sources was used to evaluate bio-ethanol
production by 11 Saccharomyces cerevisiae strains. The industrial strains PE-2 and CA1185 exhibited the best overall fermentation performance, producing an ethanol
titre of 19.2% (v/v) corresponding to a batch productivity of 2.5 g l−1 h−1, while the best laboratory strain (CEN.PK 113-7D) produced 17.5% (v/v) ethanol with a productivity of 1.7 g l−1 h−1. The results presented here emphasize the biodiversity found within S. cerevisiae species and that naturally adapted strains, such as PE-2 and CA1185, are likely to play a key role in facilitating the transition
from laboratory technological breakthroughs to industrial-scale bio-ethanol fermentations. 相似文献
16.
Compared with steady state, oscillation in continuous very-high-gravity ethanol fermentation with Saccharomyces cerevisiae improved process productivity, which was thus introduced for the fermentation system composed of a tank fermentor followed
by four-stage packed tubular bioreactors. When the very-high-gravity medium containing 280 g l−1 glucose was fed at the dilution rate of 0.04 h−1, the average ethanol of 15.8% (v/v) and residual glucose of 1.5 g l−1 were achieved under the oscillatory state, with an average ethanol productivity of 2.14 g h−1 l−1. By contrast, only 14.8% (v/v) ethanol was achieved under the steady state at the same dilution rate, and the residual glucose was as high as 17.1 g l−1, with an ethanol productivity of 2.00 g h−1 l−1, indicating a 7% improvement under the oscillatory state. When the fermentation system was operated under the steady state
at the dilution rate of 0.027 h−1 to extend the average fermentation time to 88 h from 59 h, the ethanol concentration increased slightly to 15.4% (v/v) and residual glucose decreased to 7.3 g l−1, correspondingly, but the ethanol productivity was decreased drastically to 1.43 g h−1 l−1, indicating a 48% improvement under the oscillatory state at the dilution rate of 0.04 h−1. 相似文献
17.
Rocha MV Rodrigues TH Melo VM Gonçalves LR de Macedo GR 《Journal of industrial microbiology & biotechnology》2011,38(8):1099-1107
The potential of cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025 was evaluated in this work. This strain was preliminarily cultivated in a synthetic medium containing glucose and xylose
and was able to produce ethanol and xylitol at pH 4.5. Next, cashew apple bagasse hydrolysate (CABH) was prepared by a diluted
sulfuric acid pretreatment and used as fermentation media. This hydrolysate is rich in glucose, xylose, and arabinose and
contains traces of formic acid and acetic acid. In batch fermentations of CABH at pH 4.5, the strain produced only ethanol.
The effects of temperature on the kinetic parameters of ethanol fermentation by K. marxianus CE025 using CABH were also evaluated. Maximum specific growth rate (μmax), overall yields of ethanol based on glucose consumption
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