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1.
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
2.
N. Barron R. Marchant L. McHale A. P. McHale 《Applied microbiology and biotechnology》1995,43(3):518-520
The thermotolerant yeast strain, Kluyveromyces marxianus IMB3, was found to be capable of ethanol production during growth at 45°C on media containing milled paper and exogenously
added commercial cellulase. At maximum achievable cellulose concentrations in shake-flask cultures, ethanol production increased
to 6.6 g/l at 45°C, representing an overall level of conversion of 21% of the maximum theoretical yield. Subsequent studies
involving variations in added cellulase concentrations to the batch systems demonstrated that ethanol yields could be increased
to 10 g/l at 45°C, which represented 39% of the maximum theoretical yield. As a result of ethanol production at 45°C in the
systems examined, we suggest that the thermotolerant ethanol-producing yeast strain K. marxianus represents a novel candidate for use in simultaneous saccharification and conversion of the resulting substrates to ethanol.
Received: 9 June 1994/Received revision: 8 August 1994/Accepted: 12 August 1994 相似文献
3.
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
4.
Characterization of the superoxide dismutase SOD1 gene of Kluyveromyces marxianus L3 and improved production of SOD activity 总被引:1,自引:0,他引:1
Raimondi S Uccelletti D Matteuzzi D Pagnoni UM Rossi M Palleschi C 《Applied microbiology and biotechnology》2008,77(6):1269-1277
Superoxide dismutase (SOD) activity is one major defense line against oxidative stress for all of the aerobic organisms, and
industrial production of this enzyme is highly demanded. The Cu/Zn superoxide dismutase gene (KmSOD1) of Kluyveromyces marxianus L3 was cloned and characterized. The deduced KmSod1p protein shares 86% and 71% of identity with Kluyveromyces lactis and Saccharomyces cerevisiae Sod1p, respectively. The characteristic motifs and the amino acid residues involved in coordinating copper and zinc and in
enzymatic function were conserved. To the aim of developing a microbial production of Cu/Zn superoxide dismutase, we engineered
the K. marxianus L3 strain with the multicopy plasmid YG-KmSOD1 harboring the KmSOD1 gene. The production of KmSOD1p in K. marxianus L3 and K. marxianus L3 (pYG-KmSOD1) in response to different compositions of the culture medium was evaluated. The highest specific activity
(472 USOD mgprot
−1) and the highest volumetric yield (8.8 × 105 USOD l−1) were obtained by the recombinant strain overexpressing KmSOD1 in the presence of Cu2+ and Zn2+ supplements to the culture media. The best performing culture conditions were positively applied to a laboratory scale fed-batch
process reaching a volumetric yield of 1.4 × 106 USOD l−1.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Development of a cost-effective glucose-corn steep medium for production of butanol by Clostridium beijerinckii 总被引:1,自引:0,他引:1
M Parekh J Formanek H P Blaschek 《Journal of industrial microbiology & biotechnology》1998,21(4-5):187-191
Corn steep water (CSW) medium (1.6% solids plus 6% glucose) was evaluated for growth and butanol production by Clostridium beijerinckii NCIMB 8052 wild-type and hyper-amylolytic, hyper-butanol-producing mutant strain BA101. CSW alone was not a suitable substrate,
whereas addition of glucose supported growth and butanol production by both strains. In a batch-scale fermentation using an
optimized 6% glucose-1.6% solids CSW medium, C. beijerinckii NCIMB 8052 and strain BA101 produced 10.7 g L−1 and 14.5 g L−1 of butanol, respectively. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and strain BA101 were 14 g L−1 and 20 g L−1, respectively. Initial fermentation in small-scale flasks containing 6% maltodextrin-1.6% solids concentration CSW medium
resulted in 6 g L−1 and 12.6 g L−1 of butanol production by C. beijerinckii NCIMB 8052 and strain BA101, respectively. CSW can serve as an economic source of nitrogen, vitamins, amino acids, minerals,
and other nutrients. Thus, it is feasible to use 6% glucose-1.6% solids CSW medium in place of semi-defined P2 medium.
Received 9 February 1998/ Accepted in revised form 1 September 1998 相似文献
6.
Analysis and optimization of a two-substrate fermentation for xylitol production using Candida tropicalis 总被引:1,自引:0,他引:1
Xylitol, a functional sweetener, was produced from xylose using Candida tropicalisATCC 13803. A two-substrate fermentation was designed in order to increase xylitol yield and volumetric productivity. Glucose
was used initially for cell growth followed by conversion of xylose to xylitol without cell growth and by-product formation
after complete depletion of glucose. High glucose concentrations increased volumetric productivity by reducing conversion
time due to high cell mass, but also led to production of ethanol, which, in turn, inhibited cell growth and xylitol production.
Computer simulation was undertaken to optimize an initial glucose concentration using kinetic equations describing rates of
cell growth and xylose bioconversion as a function of ethanol concentration. Kinetic constants involved in the equations were
estimated from the experimental results. Glucose at 32 g L−1 was estimated to be an optimum initial glucose concentration with a final xylose concentration of 86 g L−1 and a volumetric productivity of 5.15 g-xylitol L−1 h−1. The two-substrate fermentation was performed under optimum conditions to verify the computer simulation results. The experimental
results were in good agreement with the predicted values of simulation with a xylitol yield of 0.81 g-xylitol g-xylose−1 and a volumetric productivity of 5.06 g-xylitol L−1 h−1.
Received 16 June 1998/ Accepted in revised form 28 February 1999 相似文献
7.
Delta-endotoxin production by a strain of Bacillus thuringiensis subsp kurstakion complex media based on crude gruel and fish meal was investigated. High proteolytic activities were concomitantly produced
with the bioinsecticide. In such complex media, the repressive regulation due to readily consumed carbon sources was partially
overcome. In order to improve substrate assimilation, 0.5 g L−1 sodium chloride and 0.1% Tween-80 were supplemented to the production medium, increasing delta-endotoxin yields when using
gruel concentrations below 59 g L−1. At and beyond 75 g L−1 gruel, delta-endotoxin yields were not affected in the presence of 0.5 g L−1 NaCl and 0.1% Tween-80, but proteolytic activity yields were remarkably reduced. Thus, the use of sodium chloride and Tween-80
allowed reduction of the initial gruel concentration to 42 g L−1 for the production of 3350 mg L−1 delta-endotoxin, while it was only 3800 mg L−1 with 92 g L−1 gruel. Moreover, similar to 0.5 g L−1 NaCl and 0.1% Tween-80, the use of 10 g L−1 sodium acetate significantly improved delta-endotoxin production and also reduced the proteolytic activity to 250 U ml−1.
Received 05 November 1998/ Accepted in revised form 19 August 1999 相似文献
8.
The use of molasses as a substrate for ethanol production by the thermotolerant yeast Kluyveromyces marxianus var. marxianus was investigated at 45°C. A maximum ethanol concentration of 7.4% (v/v) was produced from unsupplemented molasses at a concentration
of 23% (v/v). The effect on ethanol production of increasing the sucrose concentration in 23% (v/v) molasses was determined.
Increased sucrose concentration had a similar detrimental effect on the final ethanol produced as the increase in molasses
concentration. This indicated that the effect may be due to increased osmotic activity as opposed to other components in the
molasses. The optimum concentration of the supplements nitrogen, magnesium, potassium and fatty acid for maximum ethanol production
rate was determined using the Nelder and Mead (Computer J 7:308–313, 1965) simplex optimisation method. The optimum concentrations
of the supplements were 0.576 g l-1 magnesium sulphate, 0.288 g l-1 potassium dihydrogen phosphate and 0.36% (v/v) linseed oil. Added nitrogen in the form of ammonium sulphate did not affect
the ethanol production rate.
Received: 29 January 1996/Received revision: 23 April 1996/Accepted: 29 April 1996 相似文献
9.
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
10.
An innovative consecutive batch fermentation process for very high gravity ethanol fermentation with self-flocculating yeast 总被引:1,自引:0,他引:1
An innovative consecutive batch fermentation process was developed for very high gravity (VHG) ethanol fermentation with the
self-flocculating yeast under high biomass concentration conditions. On the one hand, the high biomass concentration significantly
shortened the time required to complete the VHG fermentation and the duration of yeast cells suffering from strong ethanol
inhibition, preventing them from losing viability and making them suitable for being repeatedly used in the process. On the
other hand, the separation of yeast cells from the fermentation broth by sedimentation instead of centrifugation, making the
process economically more competitive. The VHG medium composed of 255 g L−1 glucose and 6.75 g L−1 each of yeast extract and peptone was fed into the fermentation system for nine consecutive batch fermentations, which were
completed within 8–14 h with an average ethanol concentration of 15% (v/v) and ethanol yield of 0.464, 90.8% of its theoretical value of 0.511. The average ethanol productivity that was calculated
with the inclusion of the downstream time for the yeast flocs to settle from the fermentation broth and the supernatant to
be removed from the fermentation system was 8.2 g L−1 h−1, much higher than those previously reported for VHG ethanol fermentation and regular ethanol fermentation with ethanol concentration
around 12% (v/v) as well. 相似文献
11.
N Kiran Sree M Sridhar K Suresh I M Banat L Venkateswar Rao 《Journal of industrial microbiology & biotechnology》2000,24(3):222-226
A repeated batch fermentation system was used to produce ethanol using an osmotolerant Saccharomyces cerevisiae (VS3) immobilized in calcium alginate beads. For comparison free cells were also used to produce ethanol by repeated batch fermentation.
Fermentation was carried for six cycles with 125, 250 or 500 beads using 150, 200 or 250 g glucose L−1 at 30°C. The maximum amount of ethanol produced by immobilized VS3 using 150 g L−1 glucose was only 44 g L−1 after 48 h, while the amount of ethanol produced by free cells in the first cycle was 72 g L−1. However in subsequent fed batch cultures more ethanol was produced by immobilized cells compared to free cells. The amount
of ethanol produced by free cells decreased from 72 g L−1 to 25 g L−1 after the fourth cycle, while that of immobilized cells increased from 44 to 72 g L−1. The maximum amount of ethanol produced by immobilized VS3 cells using 150, 200 and 250 g glucose L−1 was 72.5, 93 and 87 g ethanol L−1 at 30°C. Journal of Industrial Microbiology & Biotechnology (2000) 24, 222–226.
Received 16 September 1999/ Accepted in revised form 22 December 1999 相似文献
12.
Increased astaxanthin production by a Phaffia rhodozyma mutant grown on date juice from Yucca fillifera 总被引:1,自引:0,他引:1
J Ramírez M L Nuñez R Valdivia 《Journal of industrial microbiology & biotechnology》2000,24(3):187-190
The wild strain and the astaxanthin-overproducing mutant strain 25–2 of Phaffia rhodozyma were analyzed in order to assess their ability to grow and synthesize astaxanthin in a minimal medium composed of g L−1: KH2PO4 2.0; MgSO4 0.5; CaCl2 0.1; urea 1.0 and supplemented with date juice of Yucca fillifera as a carbon source (yuca medium). The highest astaxanthin production (6170 μg L−1) was obtained at 22.5 g L−1 of reducing sugars. The addition of yeast extract to the yuca medium at concentrations of 0.5–3.0 g L−1 inhibited astaxanthin synthesis. The yuca medium supported a higher production of astaxanthin, 2.5-fold more than that observed
in the YM medium. Journal of Industrial Microbiology & Biotechnology (2000) 24, 187–190.
Received 14 July 1999/ Accepted in revised form 02 December 1999 相似文献
13.
Aims: Developing an innovative process for ethanol fermentation from Jerusalem artichoke tubers under very high gravity (VHG) conditions. Methods and Results: A consolidated bioprocessing (CBP) strategy that integrated inulinase production, saccharification of inulin contained in Jerusalem artichoke tubers and ethanol production from sugars released from inulin by the enzyme was developed with the inulinase‐producing yeast Kluyveromyces marxianus Y179 and fed‐batch operation. The impact of inoculum age, aeration, the supplementation of pectinase and nutrients on the ethanol fermentation performance of the CBP system was studied. Although inulinase activities increased with the extension of the seed incubation time, its contribution to ethanol production was negligible because vigorously growing yeast cells harvested earlier carried out ethanol fermentation more efficiently. Thus, the overnight incubation that has been practised in ethanol production from starch‐based feedstocks is recommended. Aeration facilitated the fermentation process, but compromised ethanol yield because of the negative Crabtree effect of the species, and increases the risk of contamination under industrial conditions. Therefore, nonaeration conditions are preferred for the CBP system. Pectinase supplementation reduced viscosity of the fermentation broth and improved ethanol production performance, particularly under high gravity conditions, but the enzyme cost should be carefully balanced. Medium optimization was performed, and ethanol concentration as high as 94·2 g l?1 was achieved when 0·15 g l?1 K2HPO4 was supplemented, which presents a significant progress in ethanol production from Jerusalem artichoke tubers. Conclusions: A CBP system using K. marxianus is suitable for efficient ethanol production from Jerusalem artichoke tubers under VHG conditions. Significance and Impact of the Study: Jerusalem artichoke tubers are an alternative to grain‐based feedstocks for ethanol production. The high ethanol concentration achieved using K. marxianus with the CBP system not only saves energy consumption for ethanol distillation, but also significantly reduces the amount of waste distillage discharged from the distillation system. 相似文献
14.
P Buzzini 《Journal of industrial microbiology & biotechnology》2000,24(1):41-45
A multivariate statistical approach was employed for the optimization of conditions for carotenoid production by Rhodotorula glutinis DBVPG 3853 from a substrate containing concentrated rectified grape must as the sole carbohydrate source. Several experimental
parameters (carbohydrate, yeast autolysate and salt concentrations, and pH) were tested at two levels by following a fractional
factorial design. Carotenogenesis was most sensitive to both initial pH and yeast autolysate concentration. A Central Composite
Design experiment was then performed by obtaining both second-order polynomial models and isoresponse diagrams where initial
pH and yeast autolysate concentration were considered as variables. In this way it was possible to determine the conditions
(pH = 5.78, yeast autolysate = 4.67 g L−1) which maximize both the concentration of total carotenoids and that of β-carotene (6.9 mg L−1 and 1100 μg L−1 of culture fluid, respectively, after 120 h of fermentation). Journal of Industrial Microbiology & Biotechnology (2000) 24, 41–45.
Received 23 February 1999/ Accepted in revised form 14 September 1999 相似文献
15.
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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