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1.
Toxic at low concentrations, phenol is one of the most common organic pollutants in air and water. In this work, phenol biodegradation
was studied in extreme conditions (80°C, pH = 3.2) in a 2.7 l bioreactor with the thermoacidophilic archaeon Sulfolobus solfataricus 98/2. The strain was first acclimatized to phenol on a mixture of glucose (2000 mg l−1) and phenol (94 mg l−1) at a constant dissolved oxygen concentration of 1.5 mg l−1. After a short lag-phase, only glucose was consumed. Phenol degradation then began while glucose was still present in the
reactor. When glucose was exhausted, phenol was used for respiration and then for biomass build-up. After several batch runs
(phenol < 365 mg l−1), specific growth rate (μX) was 0.034 ± 0.001 h−1, specific phenol degradation rate (qP) was 57.5 ± 2 mg g−1 h−1, biomass yield (YX/P) was 52.2 ± 1.1 g mol−1, and oxygen yield factor
( \textY\textX/\textO 2 ) \left( {{\text{Y}}_{{{\text{X}}/{\text{O}}_{ 2} }} } \right) was 9.2 ± 0.2 g mol−1. A carbon recovery close to 100% suggested that phenol was exclusively transformed into biomass (35%) and CO2 (65%). Molar phenol oxidation constant
( \textY\textO 2 /\textP ) \left( {{\text{Y}}_{{{\text{O}}_{ 2} /{\text{P}}}} } \right) was calculated from stoichiometry of phenol oxidation and introducing experimental biomass and CO2 conversion yields on phenol, leading to values varying between 4.78 and 5.22 mol mol−1. Respiratory quotient was about 0.84 mol mol−1, very close to theoretical value (0.87 mol mol−1). Carbon dioxide production, oxygen demand and redox potential, monitored on-line, were good indicators of growth, substrate
consumption and exhaustion, and can therefore be usefully employed for industrial phenol bioremediation in extreme environments. 相似文献
2.
Sachin Kumar Surendra P. Singh Indra M. Mishra Dilip K. Adhikari 《Journal of industrial microbiology & biotechnology》2009,36(12):1483-1489
A yeast strain Kluyveromyces sp. IIPE453 (MTCC 5314), isolated from soil samples collected from dumping sites of crushed sugarcane bagasse in Sugar Mill,
showed growth and fermentation efficiency at high temperatures ranging from 45°C to 50°C. The yeast strain was able to use
a wide range of substrates, such as glucose, xylose, mannose, galactose, arabinose, sucrose, and cellobiose, either for growth
or fermentation to ethanol. The strain also showed xylitol production from xylose. In batch fermentation, the strain showed
maximum ethanol concentration of 82 ± 0.5 g l−1 (10.4% v/v) on initial glucose concentration of 200 g l−1, and ethanol concentration of 1.75 ± 0.05 g l−1 as well as xylitol concentration of 11.5 ± 0.4 g l−1 on initial xylose concentration of 20 g l−1 at 50°C. The strain was capable of simultaneously using glucose and xylose in a mixture of glucose concentration of 75 g l−1 and xylose concentration of 25 g l−1, achieving maximum ethanol concentration of 38 ± 0.5 g l−1 and xylitol concentration of 14.5 ± 0.2 g l−1 in batch fermentation. High stability of the strain was observed in a continuous fermentation by feeding the mixture of glucose
concentration of 75 g l−1 and xylose concentration of 25 g l−1 by recycling the cells, achieving maximum ethanol concentration of 30.8 ± 6.2 g l−1 and xylitol concentration of 7.35 ± 3.3 g l−1 with ethanol productivity of 3.1 ± 0.6 g l−1 h−1 and xylitol productivity of 0.75 ± 0.35 g l−1 h−1, respectively. 相似文献
3.
4.
Kinetics of styrene biodegradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. E-93486 总被引:1,自引:0,他引:1
The research into kinetics of styrene biodegradation by bacterial strain Pseudomonas sp. E-93486 coming from VTT Culture Collection (Finland) was presented in this work. Microbial growth tests in the presence
of styrene as the sole carbon and energy source were performed both in batch and continuous cultures. Batch experiments were
conducted for initial concentration of styrene in the liquid phase changed in the range of 5–90 g m−3. The Haldane model was found to be the best to fit the kinetic data, and the estimated constants of the equation were: μ
m = 0.1188 h−1, K
S = 5.984 mg l−1, and K
i = 156.6 mg l−1. The yield coefficient mean value
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} for the batch culture was 0.72 gdry cells weight (gsubstrate)−1. The experiments conducted in a chemostat at various dilution rates (D = 0.035–0.1 h−1) made it possible to determine the value of the coefficient for maintenance metabolism m
d = 0.0165 h−1 and the maximum yield coefficient value
Y\textxs\textM = 0.913 Y_{\text{xs}}^{\text{M}} = 0.913 . Chemostat experiments confirmed the high value of yield coefficient
Y\textxs\textapp Y_{\text{xs}}^{\text{app}} observed in the batch culture. The conducted experiments showed high activity of the examined strain in the styrene biodegradation
process and a relatively low sensitivity to inhibition of its growth at higher concentrations of styrene in the solution.
Such exceptional features of Pseudomonas sp. E-93486 make this bacterial strain the perfect candidate for technical applications. 相似文献
5.
Laura Pinilla Rodrigo Torres Claudia Ortiz 《World journal of microbiology & biotechnology》2011,27(11):2521-2528
Two wild strains of Zymomonas mobilis were isolated (named as ML1 and ML2) from sugar cane molasses obtained from different farms of Santander, Colombia. Initially,
selection of the best ethanol-producer strains was carried out using ethanol production parameters obtained with a commercial
strain Z. mobilis DSM 3580. Three isolated strains were cultivated in a culture medium containing yeast extract, peptone, glucose and salts,
at pH 6 and 32°C with stirring rate of 65 rpm during 62 h. The best results of ethanol production were obtained with the native
strain ML1, reaching a maximum ethanol concentration of 79.78 g l−1. ML1 and ML2 strains were identified as Z.
mobilis, according to the morphology, biochemical tests and molecular characterization by PCR of specific DNA sequences from Z. mobilis. Subsequently, the effect of different nitrogen sources on production of ethanol was evaluated. The best results were obtained
using urea at a 0.73 g/l. In this case, maximum concentration of ethanol was 83.81 g l−1, with kinetic parameters of yield of ethanol on biomass (YP/X) = 69.01(g g−1), maximum volumetric productivity of ethanol (Qpmax) = 2.28 (g l−1 h−1), specific productivity of ethanol (qP) = 3.54 (h−1) and specific growth rate (μ) = 0.12 h−1. Finally, we studied the effect of different culture conditions (pH, temperature, stirring, C/N ratio) with a Placket-Burman′s
experimental design. This optimization indicated that the most significant variables were temperature and stirring. In the
best culture conditions a significant increase in all variables of response was achieved, reaching a maximum ethanol concentration
of 93.55 g l−1. 相似文献
6.
Mateus Schreiner Garcez Lopes Rafael Costa Santos Rocha Sandra Patricia Zanotto José Gregório Cabrera Gomez Luiziana Ferreira da Silva 《World journal of microbiology & biotechnology》2009,25(10):1751-1756
Although xylose is a major constituent of lignocellulosic feedstock and the second most abundant sugar in nature, only 22%
of 3,152 screened bacterial isolates showed significant growth in xylose in 24 h. Of those 684, only 24% accumulated polyhydroxyalkanoates
after 72 h. A mangrove isolate, identified as Bacillus sp. MA3.3, yielded the best results in literature thus far for Gram-positive strains in experiments with glucose and xylose
as the sole carbon source. When glucose or xylose were supplied, poly-3-hydroxybutyrate (PHB) contents of cell dry weight
were, respectively, 62 and 64%, PHB yield 0.25 and 0.24 g g−1 and PHB productivity (PPHB) 0.10 and 0.06 g l−1 h−1. This 40% PPHB difference may be related to the theoretical ATP production per 3-hydroxybutyrate (3HB) monomer calculated as 3 mol mol−1 for xylose, less than half of the ATP/3HB produced from glucose (7 mol mol−1). In PHB production using sugar mixtures, all parameters were strongly reduced due to carbon catabolite repression. PHB production
using Gram-positive strains is particularly interesting for medical applications because these bacteria do not produce lipopolysaccharide
endotoxins which can induce immunogenic reactions. Moreover, the combination of inexpensive substrates and products of more
value may lead to the economical sustainability of industrial PHB production. 相似文献
7.
Hong-Yang Zhu Hong Xu Xiao-Yan Dai Yang Zhang Han-Jie Ying Ping-Kai Ouyang 《Bioprocess and biosystems engineering》2010,33(5):565-571
A new yeast, isolated from natural osmophilic sources, produces d-arabitol as the main metabolic product from glucose. According to 18S rRNA analysis, the NH-9 strain belongs to the genus
Kodamaea. The optimal culture conditions for inducing production of d-arabitol were 37 °C, neutral pH, 220 rpm shaking, and 5% inoculum. The yeast produced 81.2 ± 0.67 g L−1
d-arabitol from 200 g L−1
d-glucose in 72 h with a yield of 0.406 g g−1 glucose and volumetric productivity
Q\textP Q_{\text{P}} of 1.128 g L−1 h−1. Semi-continuous repeated-batch fermentation was performed in shaker-flasks to enhance the process of d-arabitol production by Kodamaea ohmeri NH-9 from d-glucose. Under repeated-batch culture conditions, the highest volumetric productivity was 1.380 g L−1 h−1. 相似文献
8.
Simultaneous bioconversion of glucose and xylose to ethanol by Saccharomyces cerevisiae in the presence of xylose isomerase 总被引:3,自引:0,他引:3
Simultaneous isomerisation and fermentation (SIF) of xylose and simultaneous isomerisation and cofermentation (SICF) of a
glucose/xylose mixture was carried out by Saccharomyces cerevisiae in the presence of xylose isomerase. The SIF of 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 7.5 g l−1 and 0.36 g (g xylose consumed)−1. These parameters improved to 13.4 g l−1 and 0.40 respectively, when borate was added to the medium. The SICF of a mixture of 50 g l−1 glucose and 50 g l−1 xylose gave an ethanol concentration and metabolic yield of 29.8 g l−1 and 0.42 respectively, in the presence of borate. Temperature modulation from 30 °C to 35 °C during fermentation further
enhanced the above parameters to 39 g l−1 and 0.45 respectively. The approach was extended to the bioconversion of sugars present in a real lignocellulose hydrolysate
(peanut-shell hydrolysate) to ethanol, with a fairly good yield.
Received: 14 May 1999 / Received revision: 27 September 1999 / Accepted: 2 October 1999 相似文献
9.
The data processing method of the turbidimetric bioassay of nisin was modified to facilitate its industrial application. The
influence of the initial indicator concentration was minimized by a redefined specific dose of the bacteriocin as the quotient
between the titer of the added bacteriocin and the initial population density of the indicator in the suspension. It was found
that d
c = 0.125 μg ml−1 was the critical dose of nisin that can cause a complete inhibition of the indicator, Pediococcus acidilactici UL5, with an initial OD of 0.135. To eliminate the interference of the cell debris, an equation, , exploiting d
c, was formulated to obtain the intrinsic survival proportion. The use of the specific dose of the bacteriocin and the intrinsic
survival proportion as parameters of the dose/response curve greatly enhanced its repeatability and feasibility. A dual-dosage
approach was developed to further simplify the conventional standard dose/response curve method. 相似文献
10.
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
11.
Sanchez-Gonzalez Y Cameleyre X Molina-Jouve C Goma G Alfenore S 《Bioprocess and biosystems engineering》2009,32(4):459-466
Dynamic Saccharomyces cerevisiae responses to increasing ethanol stresses were investigated to monitor yeast viability and to optimize bioprocess performance
when gradients occurred due to the specific configuration of multi-stage bioreactors with cell recycling or of large volume
industrial bioreactors inducing chemical heterogeneities. Twelve fed-batch cultures were carried out with initial ethanol
concentrations (P
in) ranging from 5 g l−1 to 110 g l−1 with three different inoculums in different physiological states in terms of viability and quantity of ethanol produced (P
o). For a given initial cell viability of 50%, the time to reach the maximum growth rate and maximum ethanol production rate
was dependent on the difference P
in − P
o. Whatever the initial physiological state, when the initial ethanol concentration P
in reached 100 g l−1, the yeasts died. Experimental results showed that the initial physiological state of the yeast was the major parameter to
determine, the microorganisms’ capacities to adapt and resist environmental changes. 相似文献
12.
Fontes CP Honorato TL Rabelo MC Rodrigues S 《Bioprocess and biosystems engineering》2009,32(4):493-499
The use of agriculture excess as substrate in industrial fermentations became an interesting alternative to reduce production
costs and to reduce negative environmental impact caused by the disposal of these products. In this work, a kinetic study
of mannitol production using cashew apple juice as substrate was studied. The carbohydrates of cashew apple juice are glucose
and fructose. Sucrose addition favored the yield of mannitol (85%) at the expense of lower productivity. The best results
were obtained applying only cashew apple juice as substrate, containing 50 g L−1 of total reducing sugar (28 g L−1 of fructose), yielding 18 g L−1 of mannitol with 67% of fructose conversion into mannitol and productivity of 1.8 g L−1 h−1. 相似文献
13.
Candida peltata NRRL Y-6888 to ferment xylose to xylitol was evaluated under different fermentation conditions such as pH, temperature, aeration,
substrate concentration and in the presence of glucose, arabinose, ethanol, methanol and organic acids. Maximum xylitol yield
of 0.56 g g−1 xylose was obtained when the yeast was cultivated at pH 6.0, 28°C and 200 rpm on 50 g L−1 xylose. The yeast produced ethanol (0.41 g g−1 in 40 h) from glucose (50 g L−1) and arabitol (0.55 g g−1 in 87 h) from arabinose (50 g L−1). It preferentially utilized glucose > xylose > arabinose from mixed substrates. Glucose (10 g L−1), ethanol (7.5 g L−1) and acetate (5 g L−1) inhibited xylitol production by 61, 84 and 68%, respectively. Arabinose (10 g L−1) had no inhibitory effect on xylitol production.
Received 24 December 1998/ Accepted in revised form 18 March 1999 相似文献
14.
Ana Maria Ronco Yareni Gutierrez Nuri Gras Luis Muñoz Gabriela Salazar Miguel N. Llanos 《Biological trace element research》2010,136(3):269-278
The objective of this study was to evaluate whether lead (Pb) and arsenic (As) levels in biological fluids were associated
to the body composition in a group of reproductive-age women. Voluntary childbearing-age women (n = 107) were divided into three groups according to their body mass index (BMI: weight/height2 (kg/m2): low weight (BMI<18.5 kg/m2), normal $ \left( {{\text{BMI}} > 19\kern1.5pt<\kern1.5pt24.9\,{{\text{kg}} \mathord{\left/{\vphantom {{\text{kg}} {{{\text{m}}^{\text{2}}}}}} \right.} {{{\text{m}}^{\text{2}}}}}} \right) $ \left( {{\text{BMI}} > 19\kern1.5pt<\kern1.5pt24.9\,{{\text{kg}} \mathord{\left/{\vphantom {{\text{kg}} {{{\text{m}}^{\text{2}}}}}} \right.} {{{\text{m}}^{\text{2}}}}}} \right) , and overweight (BMI>25 kg/m2). Body composition and fat mass percentage were determined by the isotopic dilution method utilizing deuterated water. Blood
lead concentrations were determined by graphite furnace atomic absorption spectrometry and urinary arsenic (AsU) concentrations
by inductively coupled plasma mass spectrometry. The type and frequency of food consumption and lifestyle-related factors
were also registered. Most women had $ {\text{PbB}}\,{\text{levels}} > 2\kern1.5pt<\kern1.5pt10\,{\mu{{\text{ g}}} \mathord{\left/{\vphantom {\mu{{\text{ g}}} {\text{dL}}}} \right.} {\text{dL}}} $ {\text{PbB}}\,{\text{levels}} > 2\kern1.5pt<\kern1.5pt10\,{\mu{{\text{ g}}} \mathord{\left/{\vphantom {\mu{{\text{ g}}} {\text{dL}}}} \right.} {\text{dL}}} , and only 2.6% had AsU concentrations above 50 μg/L. The levels of these toxic elements were not found to be associated with
the fat mass percentage. 相似文献
15.
Continuous production of acetone, n-butanol, and ethanol (ABE) was carried out using immobilized cells of Clostridium acetobutylicum DSM 792 using glucose and sugar mixture as a substrate. Among various lignocellulosic materials screened as a support matrix,
coconut fibers and wood pulp fibers were found to be promising in batch experiments. With a motive of promoting wood-based
bio-refinery concept, wood pulp was used as a cell holding material. Glucose and sugar mixture (glucose, mannose, galactose,
arabinose, and xylose) comparable to lignocellulose hydrolysate was used as a substrate for continuous production of ABE.
We report the best solvent productivity among wild-type strains using column reactor. The maximum total solvent concentration
of 14.32 g L−1 was obtained at a dilution rate of 0.22 h−1 with glucose as a substrate compared to 12.64 g L−1 at 0.5 h−1 dilution rate with sugar mixture. The maximum solvent productivity (13.66 g L−1 h−1) was obtained at a dilution rate of 1.9 h−1 with glucose as a substrate whereas solvent productivity (12.14 g L−1 h−1) was obtained at a dilution rate of 1.5 h−1 with sugar mixture. The immobilized column reactor with wood pulp can become an efficient technology to be integrated with
existing pulp mills to convert them into wood-based bio-refineries. 相似文献
16.
V. G. Dinkel F. B. Frechen A. V. Dinkel Yu. Yu. Smirnov S. V. Kalyuzhnyi 《Applied Biochemistry and Microbiology》2010,46(7):712-718
A kinetic model has been developed and kinetic parameters of anaerobic degradation of glycerol, an abundant by-product of
biofuel manufacturing, by a consortium of sulfate reducing bacteria (SRB) in a closed system have been determined. The following
main species of SRB has been identified in the consortium: Desulfovibrio baarsii, Desulfomicrobium sp., and Desufatomaculum sp. The proposed model included processes of glycerol degradation, sulfate reduction, and inhibition by metabolic products,
as well as effects of pH and temperature. The suggested equation for the anaerobic glycerol degradation was based on Edward
and Andrew’s equation. The following kinetic parameters of the anaerobic glycerol degradation were obtained for the initial
glycerol concentration from 0.15 to 4 ml/l and sulfate concentration of 2760 mg/l at 22°C: maximum specific growth rate of
SRB μmax = 0.56 day−1, economic coefficient of ashless biomass from glycerol of 0.08 mol SRB/mol COC, and yield of ashless biomass from sulfate
of 0.020 mol SRB/mol SO4. It was shown that the optimum molar ratio of $
{{C_{Gl} } \mathord{\left/
{\vphantom {{C_{Gl} } {C_{SO_4 } }}} \right.
\kern-\nulldelimiterspace} {C_{SO_4 } }}
$
{{C_{Gl} } \mathord{\left/
{\vphantom {{C_{Gl} } {C_{SO_4 } }}} \right.
\kern-\nulldelimiterspace} {C_{SO_4 } }}
for SRB growth was 0.8. Initial boundary concentration of inhibition by undissociated hydrogen sulfide was 70 mg/l. Dependence
of the specific growth rate of bacteria on the temperature was approximated by the Arrhenius equation in the temperature range
of 20–30°C with the goodness of fit R2 = 0.99. 相似文献
17.
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
18.
Yang Guo Qiaojuan Yan Zhengqiang Jiang Chao Teng Xinlei Wang 《Journal of industrial microbiology & biotechnology》2010,37(11):1137-1143
The aim of this study is to investigate production of l-lactic acid from sucrose and corncob hydrolysate by the newly isolated R. oryzae GY18. R. oryzae GY18 was capable of utilizing sucrose as a sole source, producing 97.5 g l−1
l-lactic acid from 120 g l−1 sucrose. In addition, the strain was also efficiently able to utilize glucose and/or xylose to produce high yields of l-lactic acid. It was capable of producing up to 115 and 54.2 g l−1 lactic acid with yields of up to 0.81 g g−1 glucose and 0.90 g g−1 xylose, respectively. Corncob hydrolysates obtained by dilute acid hydrolysis and enzymatic hydrolysis of the cellulose-enriched
residue were used for lactic acid production by R. oryzae GY18. A yield of 355 g lactic acid per kg corncobs was obtained after 72 h incubation. Therefore, sucrose and corncobs could
serve as potential sources of raw materials for efficient production of lactic acid by R. oryzae GY18. 相似文献
19.
The maximum ethanol concentration produced from glucose in defined media at 45°C by the thermotolerant yeast Kluyveromyces marxianus IMB3 was 44 g L−1. Acclimatisation of the strain through continuous culture at ethanol concentrations up to 80 g L−1, shifted the maximum ethanol concentration at which growth was observed from 40 g L−1 to 70 g L−1. Four isolates were selected from the continuous culture, only one of which produced a significant increase in final ethanol
concentration (50 ± 0.4 g L−1), however in subsequent fermentations, following storage on nutrient agar plates, the maximum ethanol concentration was comparable
with the original isolate. The maximum specific ethanol production rates (approximately 1.5 g (gh)−1) were also comparable with the original strain except for one isolate (0.7 g (gh)−1). The specific ethanol productivity decreased with ethanol concentration; this decrease correlated linearly (rval 0.92) with
cell viability. Due to the transience of induced ethanol tolerance in the strain it was concluded that this was not a valid
method for improving final ethanol concentrations or production rates.
Received 18 July 1997/ Accepted in revised form 19 February 1998 相似文献
20.
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