共查询到20条相似文献,搜索用时 447 毫秒
1.
Moon H Kim SW Lee J Rhee SK Choi ES Kang HA Kim IH Hong SI 《Applied biochemistry and biotechnology》2003,111(2):65-80
As a novel feeding strategy for optimizing human epidermal growth factor (hEGF) production with a recombinant Hansenula polymorpha DL-1 using the methanol oxidase (MOX) promoter in H. polymorpha DL-1, independent exponential feeding of two substrates was used. A simple kinetic model considering the cell growth on two substrates was established and used to calculate the respective feeding rates of glycerol and methanol. In the fedbatch culture with methanol-only feeding, the optimal set point of specific growth rate on methanol was found to be 0.10 h-1. When the fed-batch cultures were conducted by the independent feeding of glycerol and methanol, the actual specific growth rate on glycerol and methanol was slightly lower than the set point of specific growth rate. By the uncoupled feeding of glycerol and methanol the volumetric productivity of hEGF increased from 6.4 to 8.0 mg/(L.h), compared with methanol-only feeding. 相似文献
2.
A fed-batch culture system with constant feeding (glucose 80 g L−1, 0.25 ml min−1) was used to study the influence of glucose on cell dry weight and exopolysaccharides production from submerged Tremella fuciformis spores in a 5-L stirred-tank bioreactor. The results showed that high levels of cell mass (9.80 g L−1) and exopolysaccharides production (3.12 g L−1) in fed-batch fermentation were obtained after 1 h of feeding, where the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.267 d−1 and 0.14 g g−1. Unlike batch fermentation, maximal cell mass and exopolysaccharides production merely reached 7.11 and 2.08 g L−1; the specific growth rate (μ) and exopolysaccharides yield on substrate consumed (YP/S) were 0.194 d−1 and 0.093 g g−1, respectively. It is concluded that the synthesis of exopolysaccharides can be promoted effectively when feeding glucose
at a late exponential phase. 相似文献
3.
V. Chiruvolu K. Eskridge J. Cregg M. Meagher 《Applied biochemistry and biotechnology》1998,75(2-3):163-173
Batch fermentations were used to study the effect of different glycerol concentrations and pH conditions on growth of recombinantPichia pastoris. Two strains ofP. pastoris were used: a wild-type in methanol utilization (Mut+) and a mutant defective in methanol utilization (Mut-). Under constant pH conditions of 5.0, glycerol concentrations up to 12% were efficiently utilized. Cell yield (Yx/s) of about 0.8 and a final cell density of about 95 g/L (dry cell) were achieved. However, there were significant differences
(probability [Pr]> F 0.0351) in specific growth rates between the initial glycerol concentrations of 2, 7, and 12%. When fermentations
were conducted without pH control, growth continued until the pH had decreased to about 2.5. Growth stopped at pH 2.2 with
uncontrolled pH, and residual glycerol concentrations were greater than 2%. As a result, Yx/s decreased to about 0.3. There were no differences between Mut+ and Mut- strains during cell growth on glycerol.
This article is published as paper No. 11607, Journal Series, Nebraska Agricultural Experiment Station, Lincoln, NE 68583-0704. 相似文献
4.
The production of yeast cell wall mannan degrading -mannosidase was studied in shake flask experiments as well as in a highly instrumented, computer-coupled bioreactor. The enzyme is predominantly excreted into the culture liquid upon submerged cultivation on yeast mannan. Only low activities were detected with mannose or glucose as carbon source whereas the enzyme formation was totally repressed by glycerol. The amount of enzyme produced is proportional to the microbial biomass formed.Carbon-unlimited cultivation on mannose, the primary product of enzymic digestion, resulted in a specific growth rate of 0.10h–1, a specific oxygen uptake rate
·h and a respiratory quotient ofRQ=1.0. Addition of yeast mannan (0.5%) to nutrient-depleted bacterial cells resulted in an almost complete utilization of this substrate, with 55% of substrate carbon being converted to biomass and 37% to carbon dioxide. The yield coefficient on mannan wasY
x/s
=0.51 (g/g). Enzyme formation started with a delay of 30–40 min and stopped with termination of growth. Due to the increased production of mannose by the action of the enzyme the specific growth rate increased from 0.05 to 0.10 h–1, thus enabling computations of maintenance and yield coefficients for oxygen and carbon dioxide metabolism. 相似文献
5.
Jean-Louis Uribelarrea José Humberto De Queiroz Alain Pareilleux 《Applied biochemistry and biotechnology》1997,66(1):69-81
The aerobic growth ofSchizosaccharomyces pombe on mixtures of glucose and malate was investigated during continuous high cell density cultures with partial cell-recycle
using a membrane bioreactor. Determination of the specific metabolic rates relative to substrates and products allowed the
capacity of the yeast to metabolize malic acid under both oxidative metabolism (carbon limited cultures) and oxidofermentative
metabolism (carbon sufficient cultures) situations to be characterized. Under carbon limiting conditions, the specific rate
of malate utilization was dependent on the residual concentration and a limit for a purely oxidative breakdown without ethanol
formation was observed for a characteristic ratio between the rates of substrate consumption qm/qg of 1.63 g.g-1. In addition, the mass balance analysis revealed the incorporation of malic acid into biomass. In carbon excess environments,
the specific rate of malate utilization was dependent on both the residual malate and the specific rate of glucose consumption
indicating that in addition to its conversion into ethanol malate can be respiratively metabolized for qm/qg ratios higher
than 0.4 g.g-1. 相似文献
6.
Min-Jie Gao Xiao-Bei Zhan Zhi-Yong Zheng Jian-Rong Wu Shi-Juan Dong Zhen Li Zhong-Ping Shi Chi-Chung Lin 《Applied biochemistry and biotechnology》2013,171(5):1262-1275
Effective expression of porcine interferon-α (pIFN-α) with recombinant Pichia pastoris was conducted in a bench-scale fermentor using an in situ methanol electrode-based feeding process with the control level of methanol concentration linearly increased to 10 g l?1 for the first 20 h and maintained at 10 g l?1 for the rest of expression phase. With this two-stage control process, the highest pIFN-α concentration reached a level of 1.81 g l?1, which was 1.5-fold of that in the previous constant 10 g l?1 induction experiments. There is an improvement of the pIFN-α productivity from more distribution of carbon flux to protein expression. The pIFN-α expression stability could be further enhanced by a simple on-line fault diagnosis method for methanol overfeeding based on oxygen uptake rate changing patterns. By implementing corrective action of feeding glycerol after fault detection, the production yield increased to twice the amount it would have been without the diagnosis. 相似文献
7.
Abdull Razis AF Ismail EN Hambali Z Abdullah MN Ali AM Mohd Lila MA 《Applied biochemistry and biotechnology》2008,144(3):249-261
Recombinant human epidermal growth factor (EGF) was successfully expressed as a fusion protein in Escherichia coli system. This system was used OmpA signal sequence to produce soluble protein into the periplasm of E. coli. Human EGF (hEGF) synthesized in bacterial cell was found to be similar in size with the original protein and molecular weight
approximately at 6.8 kDa. Cell proliferation assay was conducted to characterize the biological activity of hEGF on human
dermal fibroblasts. The synthesized hEGF was found to be functional as compared with authentic hEGF in stimulating cell proliferation
and promoting growth of cell. In comparison of biological activity between synthesized and commercial hEGF on cell proliferation,
the results showed there was no significant different. This finding indicates the synthesized hEGF in E. coli system is fully bioactive in vitro. 相似文献
8.
Celso Ricardo Denser Pamboukian Maria Câandida Reginato Facciotti 《Applied biochemistry and biotechnology》2004,112(2):111-121
Fed-batch runs were performed in order to correlate the production of retamycin, an anthracycline antibiotic produced by Streptomyces olindensis in submerged cultures, with the specific growth rate. Maximum retamycin production was achieved with an exponential feed
rate, controlling the specific growth rate at a low value (0.03h−1, about 10% of the maximum specific growth rate). Control of the specific growth rate at higher values (0.10 and 0.17 h−1) caused a decrease in antibiotic production. Morphology, assessed by image analysis, was shown to be highly relevant in this
process. Cell growth mainly in the form of clumps (90% clumps and 10% free filaments) led to better results than growth as
clumps (75%) and free filaments (25%). 相似文献
9.
Daniele Misturini Rossi Elisangela Aquino de Souza Marco Antônio Záchia Ayub 《Applied biochemistry and biotechnology》2013,169(6):1952-1964
The metabolism of residual glycerol from biodiesel synthesis by Klebsiella pneumoniae BLh-1 was investigated in this study. Batch and fed-batch cultivations were performed in bioreactors under anaerobic and oxygen limitation conditions. Results of batch cultivations showed that the main product was 1,3-propanediol (1,3-PD) in both conditions, although the higher yields and productivities (0.46 mol mol?1 glycerol and 1.22 g?L?1?h?1, respectively) were obtained under anaerobic condition. Large amounts of ethanol were also produced under batch anaerobic condition, peaking at 12.30 g?L?1. Batch cultivations under oxygen limitation were characterized by faster growth kinetics, with higher biomass production but lower conversions of glycerol into 1,3-PD, with yields and productivities of 0.33 mol mol?1 glycerol and 0.99 g?L?1?h?1, respectively. The fed-batch cultivations were carried out in order to investigate the effects of feeding of raw glycerol on cells. Fed-batch under anaerobiosis showed that 1,3-PD and ethanol concentrations increased with the feeding rate, with maximal productions of 26.12 and 19.2 g?L?1, respectively. The oxygen limitation conditions diverted the bacterium metabolism to an elevated lactic acid formation, reaching 59 g?L?1 in higher feeding rates of glycerol, but lowering the production of ethanol. 相似文献
10.
11.
Optimal design and operation of bioreactors for insect cell culture is facilitated by functional relations providing quantitative
information on cellular metabolite consumption kinetics, as well as on the specific cell growth rates (μG). Initial specific consumption rates of glucose, malate, and oxygen, and associated changes in μG, were measured forSpodoptera frugiperda clone 9 (Sf9) cells grown in batch suspension culture in medium containing 7–35 mM glucose, 0–16 mM malate, and 4–16 mM glutamine.
The initial specific glucose consumption rate (q
G
) could be described by a modified Michaelis-Menten equation treating malate as a “competitive” inhibitorK
1 = 6.5 mM) and glutamine as a “noncompetitive” inhibitorK
I
= 14 mM) ofq
G
, with aK
m
of 7.1 mM for glucose. All three carbon sources were found to increase μG in a saturable manner, and a modified Monod equation was employed to describe this relationship (μGmax = 0.047 h-1). The initial specific oxygen consumption rate (qO2) in Sf9 cells could be related to μG by the maintenance energy model, and it was calculated that, under typical culture conditions, about 15–20% of the cellular
energy demand comes from functions not related to growth. Fitted parameters in mathematical expression for μg: K4, Monod constant for glucose (mM); K5, modified Monod constant for malate (mM); K6, Monod constant for glutamine (mM); mo2, specific consumption rate of oxygen by the cells under zero-growth conditions (nmol/cell/h); qF, initial specific fumarate production rate (nmol/cell/ h);q
G
, initial specific glucose consumption rate (nmol/cell/h); qGmax, maximum initial specific glucose consumption rate (nmol/cell/h);q
M
, initial specific malate consumption rate (nmol/cell/h); qo2, initial specific oxygen consumption rate (nmol/cell/h); Yo2, cell yield on oxygen (cells/nmol); μ, initial specific cell growth rate (h-1); μg, initial specific cell growth rate (h-1); μGmax, maximum initial specific cell growth rate (h-1). 相似文献
12.
Production of indole-containing metabolites (“indoles”) from methanol has been studied using a mutant ofHansenula polymorpha resistant to 5-fluorotryptophan. Whereas the wild-type culture produces only a small amount of indoles, the mutant is partially
deregulated and overproduces indoles. Indoles production was studied in batch and continuous culture and in a washed-cell
system. When the pH was above 4.0, indoles production was growth-associated, in both minimal and complex media, and batch
or continuous culture. When the pH was below or equal to 4.0, a low phosphate concentration was found to improve production.
In a phosphate-deficient washed-cell suspension system, the addition of an amino acid such as methionine at 5 mM increased specific productivity by more than 60%. Addition of cycloheximide at 50 mg/L decreased residual growth and increased
maximum productivity of indoles by more than 60%. When the antibiotic was added at 1000 mg/L, growth was completely inhibited
and indoles production continued for about 35 h. 相似文献
13.
The rate constant of alkaline fading of malachite green (MG+) was studied in alcohol–water binary mixtures. This reaction was studied under pseudo‐first‐order conditions at 283–303 K. It was observed that the reaction rate constants were increased in the presence of different weight percentages of methanol, ethanol, 1‐propanol, 2‐propanol, ethylene glycol, 1,2‐propanediol, and glycerol (up to 19.3%). In aqueous glycerol solutions higher than 19.3%, the rate constant of reaction slightly decreases, which is due to high viscosity values of solvent mixtures. The fundamental rate constants of MG+ fading in these solutions were obtained by using the SESMORTAC model. Owing to the charged character of activated complex, with an increase in the weight percentage of the used cosolvents or temperature, k2 values change according to the trend of hydroxide ion nucleophilic parameter values. Also, using MG+ solvatochromism, a simple test, called MAGUS, is introduced for measuring the glycerol concentration in its aqueous solutions. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 508–518, 2010 相似文献
14.
Kinetics and bioenergetics of Spirulina platensis cultivation by fed-batch addition of urea as nitrogen source 总被引:1,自引:0,他引:1
Sassano CE Carvalho JC Gioielli LA Sato S Torre P Converti A 《Applied biochemistry and biotechnology》2004,112(3):143-150
The cyanobacterium Spirulina platensis was cultivated in bench-scale miniponds on bicarbonate/carbonate solutions using urea as nitrogen source. To minimize limitation
and inhibition phenomena, urea was supplied semicontinuously using exponentially increasing feeding rates. The average growth
rates obtained alternately varying the total mass of urea added per unit reactor volume (275<m
T<725 mg/L) and the total feeding time (9<t
T<15 d) clearly evidenced nitrogen limitation for m
T<500 mg/L and excess nitrogen inhibition above this threshold. The time behavior of the specific growth rate at variable urea
feeding patterns allowed estimation of the time-dependent Gibbsenergy dissipation for cell growth under the actual depletion
conditions of fed-batch cultivations. Comparison of the yield of growth on Gibbs energy obtained using either urea or KNO3 pointed to the preference of S. platensis for the former nitrogen source, likely owing to more favorable bioenergetic conditions. 相似文献
15.
Simultaneous production of citric acid and erythritol from crude glycerol by Yarrowia lipolytica Wratislavia K1 总被引:2,自引:0,他引:2
This study shows a possible microbial process for utilization of crude glycerol generated by the biodiesel industry for citric
acid and erythritol production. Simultaneous production of citric acid and erythritol under nitrogen-limited conditions with
glycerol as the carbon source was achieved with an acetate negative mutant of Y. lipolytica Wratislavia K1 in fed-batch cultivations. The effect of the initial glycerol concentration (from 30–180 g dm−3) on the citrate and erythritol production was investigated. As a result of the experiments, maximum citric acid production
(110 g dm−3) and a very high amount of erythritol (81 g dm−3) were determined after 168 h of fed-batch cultivation with the initial glycerol concentration of 150 g dm−3 and the total glycerol concentration of 250 g dm−3. In addition, the citric acid to isocitric acid ratio of the products from this strain was 35.5:1.
Presented at the 34th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 21–25 May
2007. 相似文献
16.
Darin Phukingngam Orathai Chavalparit Dararat Somchai Maneerat Ongwandee 《Chemical Papers》2011,65(5):644-651
Biodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater
containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic
treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal
and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m−3 d−1 to 3.0 kg m−3 d−1 of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater
was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic
baffled reactor operated at 1.5 kg m−3 d−1 of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical
oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m−3 d−1 of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable
for methanogenesis. The biogas production rate was 12 L d−1 and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen
demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally.
A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external
surface of the granular sludge was Methanosarcina. 相似文献
17.
A mutant strain ofPichia stipitis, FPL-061, was obtained by selecting for growth on L-xylose in the presence of respiratory inhibitors. The specific fermentation
rate of FPL-061, was higher than that of the parent,Pichia stipitis CBS 6054, because of its lower cell yield and growth rate and higher specific substrate uptake rate. With a mixture of glucose
and xylose, the mutant strain FPL-061 produced 29.4 g ethanol/L with a yield of 0.42 g ethanol/g sugar consumed. By comparison,
CBS 6054 produced 25.7 g ethanol/L with a yield of 0.35 gJg. The fermentation was most efficient at an aeration rate of 9.2
mmoles O2 L-1 h-1. At high aeration rates (22 mmoles O2 L-1 h-1), the mutant cell yield was less than that of the parent. At low aeration rates, (1.1 to 2.5 O2 L-1 h-1), cell yields were similar, the ethanol formation rates were low, and xylitol accumulation was observed in both the strains.
Both strains respired the ethanol once sugar was exhausted. We infer from the results that the mutant, P.stipitis FPL-061, diverts a larger fraction of its metabolic energy from cell growth into ethanol production. 相似文献
18.
Pinheiro AD Rocha MV Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2008,148(1-3):227-234
A commercial strain of Saccharomyces cerevisiae was used for the production of ethanol by fermentation of cashew apple juice. Growth kinetics and ethanol productivity were
calculated for batch fermentation with different initial sugar (glucose + fructose) concentrations. Maximal ethanol, cell,
and glycerol concentrations were obtained when 103.1 g L−1 of initial sugar concentration was used. Cell yield (Y
X/S) was calculated as 0.24 (g microorganism)/(g glucose + fructose) using cashew apple juice medium with 41.3 g L−1 of initial sugar concentration. Glucose was exhausted first, followed by fructose. Furthermore, the initial concentration
of sugars did not influence ethanol selectivity. These results indicate that cashew apple juice is a suitable substrate for
yeast growth and ethanol production. 相似文献
19.
T M Chen 《Photochemistry and photobiology》1970,12(2):81-90
Abstract— The electron spin resonances of the metastable triplet states of DL-5-hydroxy-tryptophan, 6-hydroxynicotinic acid, and other related compounds have been observed in various glasses at 77°K. These compounds are biologically interesting in connection with photochemical processes. The Δm= 2 transitions were observed and the spin-spin interaction parameter (D2+ 3E21/2 was determined. However, for indole, it was also able to observe the Δm= 1 transitions from which D and E were determined separately. From the values of (D2+ 3E2)1/2, D and E whenever possible and from the decay times of the triplet states, it was possible to characterize the lowest triplets as π—π* states in all cases. Studies of the pH dependence of DL-5-hydroxytryptophan, 5-hydroxyindole, and 6-hydroxynicotinic acid indicate that the unionized molecule exhibits a resonance different from that of the related ion with a proton removed from the phenolic hydroxyl group. The zero-field splitting parameters D* and the lifetime of the triplet states have also been measured in various glasses and in Lucite. Both temperature and the specific nature of the host media affected the values of these parameters. 相似文献
20.
Three acetate mutants of the yeast species Yarrowia lipolytica were screened using batch cultivation. The strain Y. lipolytica 1.31 was found to be the most suitable for citric acid production from raw glycerol, a by-product of biodiesel production
from rapeseed oil. At the initial concentration of glycerol of 200 g dm−3, the citric acid production of 124.5 g dm−3, yield of 0.62 g g−1, and productivity of 0.88 g dm−3 h−1 were achieved.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献