共查询到20条相似文献,搜索用时 31 毫秒
1.
Oxygen-transfer demand of Bacillus lichenioformis under conditions of submerged cultivation
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have studied the influence of oxygen transfer in the biosynthesis of bacitracin. The intensity of oxygen transfer within the range of 0.37 to 2.43 ml of O(2) per ml per hr during growth of the inoculum has no effect. The production of bacitracin is very important in the actual fermentation phase. Oxygen transfer must not fall below the lowest limit; in the case of fermentation medium with 5 and 6% peanut meal, 0.97 and 1.39 ml of O(2) per ml per hr, respectively, are the limits. Increased oxygen-transfer above the optimal value does not lead to a reduced production of bacitracin. 相似文献
2.
Whole cells of Bacillus sp., a bacitracin-producing bacteria, were immobilized in polyacrylamide gel. The continuous production of bacitracin by an immobilized whole-cell-containing air-bubbled reactor was examined with 0.5% peptone solution. The bacitracin productivity (28 units/ml/hr) obtained with this system was higher than that with a batch system. The effluent bacitracin concentration increased with increasing aeration rate and reached a steady-state maximum above the aeration rate of 3.0 liter/min. A high bacitracin productivity was retained for at least eight days when the gel was washed with sterilized saline at a flow rate of 250 ml/hr for 2 hr once a day. The half-life of the immobilized whole-cell system was about 10 days. Bacitracin productivity by the immobilized whole-cell reactor was higher than that by a conventional continuous fermentation process at high dilution rates. 相似文献
3.
Gas Exchange with Mass Cultures of Algae: I. Effects of Light Intensity and Rate of Carbon Dioxide Input on Oxygen Production 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The performance of a small photosynthetic gas exchanger is described in which simultaneous measurements of suspension density, O2 production, and CO2 absorption are readily accomplished. The volume of suspension was 6200 ml. With the Sorokin strain of Chlorella pyrenoidosa 7-11-05, this unit produced 4500 cc of O2 per hr at a light intensity of 34,000 ft-c from each of six Quartzline lamps. At any given light intensity, the O2 production was proportional to the rate of CO2 input up to a maximum. The impetus for this study was the consideration of the algal system as a means of oxygen generation in a submarine. Based on the performance of this unit, the power requirement per man for a system having the geometry described would be 52 kw, but reasons are given for the hope that this may be reduced to less than 5 kw. 相似文献
4.
This investigation used the glucose oxidase system to simulate oxygen transfer rate in fermentation broths. It was demonstrated that the fungal preparation contained sufficient lactonase activity so that D -glucono-δ-lactone did not accumulate and that the rate of production of gluconic acid was proportional to the oxygen uptake rate. Enzyme concentrations of 1.5–2 g/1 were found adequate to determine oxygen absorption rates in shake flasks while maintaining the dissolved oxygen concentration of low levels. The apparent Michaelis constant for oxygen, Km(O2), was found to be 27% saturation with air; this value along with experimentally determined uptake rates could be used to calculate dissolved oxygen concentration in lieu of using a dissolved oxygen probe. Enzyme concentrations of 5 g/l were sufficient to give linear acid production and low dissolved oxygen concentrations in a bench-scale fermenter with no foaming or enzyme deactivation. The method is considered more valid and easier to employ than previously utilized techniques such as sulfite oxidation. Extension of the system to evaluating aeration effectiveness and scaleup of fermentation equipment is discussed. 相似文献
5.
《Bioscience, biotechnology, and biochemistry》2013,77(9):1608-1612
This work was designed to examine culture variables influencing the production of uridine by the Bacillus subtilis mutant No. 556. A combination of corn steep liquor (4%) + corn gluten meal (0.7%) + urea (2%) was the most suitable nitrogen source for the production of uridine; a high level of ammonium ions in the medium brought about abundant cell growth in the early stage of incubation and was detrimental to the fermentation. The addition of calcium salts, such as CaCO3 and CaCl2, was also essential for obtaining high yields of uridine. Among the carbon sources tested, glucose gave the best result. The optimum temperature and oxygen transfer rate for producing uridine were around 38°C and 20 × 10?7 mol O2/min/ml, respectively. Under optimum conditions in a 6000-liter fermentor, strain No. 556 produced 65mg/ml of uridine from 18% glucose. 相似文献
6.
The role of aeration and agitation in the production of glucose oxidase in submerged culture. II 总被引:1,自引:0,他引:1
K Z Zetelaki 《Biotechnology and bioengineering》1970,12(3):379-397
The main purpose of the work reported here was to establish the effectiveness of aeration and agitation, and to determine the best conditions of aeration for the growth and production of glucose oxidase of Aspergillus niger, on a semi-industrial scale. Concentration of dissolved O2, O2 consumption and CO2 production were measured. It was found that the rate of growth and the activity of glucose oxidase per gram mycelium increased with the increase of speed of agitation. The concentration of dissolved oxygen of the fermentation broth, as well as the rate of respiration (O2 consumption and CO2 production) increased in direct proportion to the increase of speed of agitation, while assimilation of sugars was accelerated. The values of the respiratory ratio showed a fluctuation according to the presence or absence of sugar in the medium. 相似文献
7.
Oxygen poisoning in Drosophila 总被引:1,自引:0,他引:1
Fruit flies live longer at the partial pressure of oxygen found in air than at either larger or smaller partial pressures. Flies exposed to 1 atm of oxygen for 8 hr every day do not recover completely in the remaining 16 hr. In general, intermittent exposures to 1 atm of oxygen are better tolerated than continuous exposure to the same average oxygen concentration per day, but exposures to higher pressures of 2–5 atm of oxygen for as little as a half hour every two days markedly shorten the life-span. Older flies consume more oxygen per minute and are more sensitive to oxygen poisoning than young flies, and the rate of dying in 6 atm of O2, or the reciprocal of the survival time, is a linear function of the age. The oxygen pressure-time curve can be well expressed by the general empirical equation (POO2)2 x time = 120 where P is in atmosphere and survival time in hours. The progress of oxygen poisoning appears to be linear with time rather than exponential. 相似文献
8.
The hyperthermophilic bacterium, Thermotoga neapolitana, has potential for use in biological hydrogen (H2) production. The objectives of this study were to (1) determine the fermentation stoichiometry of Thermotoga neapolitana and examine H2 production at various growth temperatures, (2) investigate the effect of oxygen (O2) on H2 production, and (3) determine the cause of glucose consumption inhibition. Batch fermentation experiments were conducted at temperatures of 60, 65, 70, 77, and 85°C to determine product yield coefficients and volumetric productivity rates. Yield coefficients did not show significant changes with respect to growth temperature and the rate of H2 production reached maximum levels in both the 77°C and 85°C experiments. The fermentation stoichiometry for T. neapolitana at 85°C was 3.8 mol H2, 2 mol CO2, 1.8 mol acetate, and 0.1 mol lactate produced per mol of glucose consumed. Under microaerobic conditions H2 production did not increase when compared to anaerobic conditions, which supports other evidence in the literature that T. neapolitana does not produce H2 through microaerobic metabolism. Glucose consumption was inhibited by a decrease in pH. When pH was adjusted with buffer addition cultures completely consumed available glucose. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
9.
A rapid and internally consistent technique has been developed to measure the volumetric oxygen transfer coefficient, kLa, in fermentation systems. The method consists of tracing the dissolved O2 concentration of the fermentation broth during a short interruption of the aeration. The O2 concentration trace thus obtained can be analyzed to determine the values of kLa. Additional experiments on prolonged O2 starvation, carried out to find the limitation of the technique, suggest that O2 uptake rate will vary if a prolonged (2–10 min.) O2 starvation occurs. 相似文献
10.
Arthur K. Balin David B. P. Goodman Howard Rasmussen Vincent J. Cristofalo 《In vitro cellular & developmental biology. Plant》1976,12(10):687-692
Summary We have investigated the atmospheric stability in polystyrene and glass cell culture vessels by measuring the dissolved O2 and CO2 in the media of both seeded and unseeded culture vessels incubated at 37°C. There was no diffusion of either O2 or CO2 through glass vessels. At low partial pressures of oxygen (PO
2), oxygen diffused into the polystyrene flasks at a rate of 1 to 2 mm Hg per 24 hr, and at high PO
2, oxygen diffused slowly out of polystyrene flasks. CO2 diffused out of polystyrene flasks with a half-time of 260 hr resulting in a considerable elevation in pH. In seeded polystyrene
flasks with the PO
2 ⩽ room air, cellular oxygen consumption was masked by the inward diffusion of oxygen. In addition, the fall in pH due to
metabolic CO2 and organic acid production during cell growth in polystyrene flasks was buffered by the diffusion of CO2 out of the vessels.
Presented, in part, by Dr. Arthur Balin in partial fulfillment of the requirements for the Ph.D.
This work was supported by USPHS grants AG-00378 from the National Institute of Aging and CA-14345 from the National Cancer
Institute and NR 202-005 from the Office of Naval Research. A.K.B. is a trainee of the Medical Scientist Training Program,
National Institutes of Health (GM 02046). 相似文献
11.
Results of pilot plant studies using an external-loop airlift bioreactor (170 l fermentation volume, liquid height-to-riser diameter: 27, loop-to-tower cross-section-area: 0.1225) have proven the relative merits of such a system in the bacitracin biosynthesis produced by the Bacillus licheniformis submerged aerobic cultivation. The results were compared to those obtained in a pilot-scale stirred-tank bioreactor with the same values of kLa. Excepting the aeration rate of 0.2 vvm, the fermentation process performed at 0.5 vvm and 1/0 vvm, respectively, unfolded similarly in the two fermentation devices with respect to the cell mass production, substrate utilization and bacitracin production during the fermentation process. In the riser section of the airlift bioreactor, the dissolved oxygen levels were higher, while in the downcomer section they were lower than those realized in the stirred tank bioreactor. Power requirements of the airlift fermenter were by 17–64% lower than those for a mechanically agitated system, depending on the aeration rates, which led to an important energy saving. Moreover, the lack of mechanical devices in the airlift system provides safety and a more gentle environment for the cultivation of microorganisms. 相似文献
12.
Observations on quantitative relationships between oxygen diffusion rate and product formation were made with penicillin, bacitracin, and gluconic acid. For penicillin and gluconic acid formation, no toxic oxygen concentration could be achieved in the broth, whereas concentration above approximately 7 mg. O2/l. suppressed the bacitracin yield to an ever increasing extent. The intensity of mixing was measured by means of distributing a dye. With penicillin formation as an example, it was shown that the antibiotic yield is not only dependent on maintenance of a certain oxygen diffusion rate, but also on ensuring a necessary minimal mixing. 相似文献
13.
《Comparative biochemistry and physiology. A, Comparative physiology》1981,68(1):103-106
- 1.1. Healthy 6- to 12-day-old Heliothis zea (bollworm) larvae showed a mean oxygen uptake of 3.1 μl O2/mg body wt per hr.
- 2.2. Similar larvae infected with the fungus Nomuraea rileyi had a mean uptake of 4.01 μl O2/mg per hr.
- 3.3. The weights of the two groups of insects did not differ.
- 4.4. T-test showed a significant (P < 0.01) difference in oxygen uptake between healthy and infected larvae.
14.
Production of 2-ketogluconic acid from glucose by fermentation with Serratia marcescens NRRL B-486 was studied in 20-liter stainless-steel fermentors. Conditions for 2-ketogluconic acid production included the following: glucose-salt medium, aeration rate of 0.75 volumes per volume per minute, agitation rate of 400 rev/min, temperature of 30 C, CaCO3 to neutralize the acid formed, and a 5% (v/v) inoculum. Foaming was controlled with an antifoam agent added at intervals during the fermentation. When 120 g per liter of glucose were supplied, 95 to 100% yields of 2-ketogluconic acid were obtained in 16 hr. Larger amounts of glucose could be used in the fermentation provided that the carbohydrate was fed continuously. Continuous feeding of glucose to a total amount of 180 g per liter gave 95 to 100% yields of 2-ketogluconic acid in 24 hr; feeding glucose to a total amount of 240 g per liter gave 85 to 90% yields in 32 to 40 hr. 相似文献
15.
Summary Parallel bench-scale activated sludge systems were operated using air or hydrogen peroxide as oxygen source. The use of H2O2 resulted in a temporary decrease of COD reduction, an increase of the catalase activity of the activated sludge, a depression of the nitrification, and a marked decrease of some filamentous organisms. Enumeration of some microbiologic groups indicated that the counts of enterobacteria, coliforms, staphylococci, and streptococci were lower in the H2O2 unit than in the parallel air unit. Also the use of H2O2 did not induce the selection of bacterial species that are more resistant to H2O2. The increase in catalase activity after H2O2 addition might be the result of a stimulation of catalase synthesis in catalase positive microorganisms.List of Abbreviation COD
chemical oxygen demand, mg O2/1
- CODeff
chemical oxygen demand of the effluent, mg O2/1
- DO
dissolved oxygen, mg O2/1
- MLSS
mixed liquor suspended solids, g dry weight/1
- SVI
sludge volume index, ml settled sludge per liter/MLSS (ml/g)
- F:M
sludge loading factor or the Food to Microorganisms ratio, g COD/g MLSS.day 相似文献
16.
J. Feng A. H. Melcher D. M. Brunette H. K. Moe 《In vitro cellular & developmental biology. Plant》1977,13(2):91-99
Summary The method of Deutsch and Weeks was modified to provide a reliable and reasonably quick method for assaying the L-ascorbic
acid content of culture medium. The modified method was used to determine the decay of L-ascorbic acid under various conditions
of culture and the concentration of the vitamin in commercially prepared media. The half-life of L-ascorbic acid in a modified
New circulator gassed with 95% O2+5% CO2 was 1.5 hr.; and when gassed with 20% O2+5% CO2+75% N2, about 2 hr. In Petri dishes gassed with 20% O2+5% CO2+75% N2, the half-life of L-ascorbic acid was 0.9 hr. About 4% of the L-ascorbic acid was lost per day when medium was stored at
0°C and about 9% per day when stored at 5°C. When medium with an initial content of 300 μg per ml was stored at room temperature,
the half-life was found to be 15.5 hr. The L-ascorbic acid in five commercially available media, which contain the vitamin
in their formulations, was assayed immediately after their delivery to the laboratory. The values of L-ascorbic acid measured
in these media were in all cases far lower than prescribed. A continuous-flow organ culture system has been designed which
allows the provision of a relatively constant level of L-ascorbic acid to an explant by taking advantage of the slow oxidation
of L-ascorbic acid at 0°C. 相似文献
17.
A mixed methane-oxidizing bacterial culture capable of stable and predictable growth in continuous culture was isolated. The culture consisted of two types of gram-negative nonsporulating rods resembling pseudomonads. The culture grew well at 45 C on an inorganic medium without asepsis. Specific metal requirements for Ca2+, Cu2+, MoO42−, Zn2+, Mn2+, Mg2+, and Fe3+ (or Fe2+) were shown. The cells grown in continuous culture contained 11.7 to 12.1% total nitrogen. From an animal nutrition standpoint, the distribution of amino acids was satisfactory. The continuous fermentation was operated over a range of steady-state dilution rates from 0.085 to 0.301 hr−1. The maximum specific growth rate for the culture, μmax, was 0.303 hr−1 (doubling time 2.29 hr). The average yield for all fermentations analyzed was 0.616 g (dry weight of cells per g of methane used and 0.215 g (dry weight) of cells per g of oxygen used. The yields on both methane and oxygen were higher for the oxygen-limited than for the methane-limited fermentations. The maximum productivity attained in the fermentor was 2.39 g (dry weight) of cells per hr per liter at a dilution rate of 0.187 hr−1 and a cell concentration of 12.8 g (dry weight) of cells per liter. The limit on maximum cell productivity was determined only by the mass transfer rate of oxygen in the fermentor. The simultaneous volumetric mass-transfer coefficients (kLa in hr−1) for oxygen and methane were determined. The results appear to indicate an oxygen to methane mass-transfer coefficient ratio of approximately 1.4. 相似文献
18.
Oxygen metabolism of mammalian spermatozoa. Generation of hydrogen peroxide by rabbit epididymal spermatozoa 总被引:7,自引:0,他引:7
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rabbit spermatozoa from the cauda epididymis produced 0.7–0.8nmol of H2O2/min per 108 cells at cell concentrations below 107 cells/ml with linear dependence on cell concentration. Above 2 × 107 cells/ml, the rate again became linear with cell concentration but decreased to 0.1–0.2nmol/min per 108 cells. Spermatozoa treated with amphotericin B, which makes the plasma membrane highly permeable to low-molecular-weight compounds, showed a similar dependence of H2O2 production rate on cell concentration; below 107 cells/ml the rate was 0.3–0.4nmol/min per 108 cells; above 2 × 107 cells/ml, the rate was 0.1–0.2nmol/min per 108 cells. Hypo-osmotically treated rabbit epididymal spermatozoa, a preparation useful for studying mitochondrial function in sperm [Keyhani & Storey (1973) Biochim. Biophys. Acta 305, 557–565] produced 0.1–0.2nmol/min per 108 cells in the absence of added substrates. The dependence of rate on cell concentration was linear from 107 to 2.2 × 108 cells/ml. This endogenous rate was unaffected by rotenone, but stimulated 4-fold by antimycin A. Addition of the mitochondrial substrates lactate plus malate increased the rate of H2O2 production to 0.3nmol/min per 108 cells. The decreased rate of H2O2 production observed with intact sperm at high cell concentrations is attributed to reaction of H2O2 with the cells, possibly with the plasma membrane, which is lost after hypo-osmotic treatment. Rabbit spermatozoa have glutathione peroxidase and glutathione reductase activities, but these seem to play little role in removal of H2O2 generated. The rate at low cell concentration is taken to be the unperturbed rate. The sources of H2O2 production in rabbit spermatozoa have been tentatively resolved into a low-molecular-weight component, lost after amphotericin treatment, a mitochondrial component and a rotenone-insensitive component that has not been identified. 相似文献
19.
Hydrogen peroxide metabolism in soybean embryonic axes at the onset of germination 总被引:18,自引:4,他引:14
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hydrogen peroxide steady state levels of 5 micromolar were determined in soybean (Glycine max) embryonic axes incubated for 2 hours and in axes pretreated with aminotriazole or cyanide, where these levels were 50 and 1 micromolar, respectively. The activities of catalase (105 picomoles H2O2 per minute per axis), peroxidase (10-44 picomoles H2O2 per minute per axis), glutathione peroxidase (3 picomoles H2O2 per minute per axis) and superoxide dismutase (3.5 units per axis), were also determined. Catalase seems to be the most important H2O2 consuming enzyme at the physiological concentration of H2O2. A short treatment with aminotriazole, while substantially increasing H2O2 level, did not affect the growth of the axes. The production of superoxide anion by the mitochondria isolated from soybean axes was measured from the superoxide dismutase-sensitive rate of adrenochrome formation in the presence of NADH or succinate as substrate and amounted to 1.3 and 0.8 nanomole O2− per minute per milligram protein, respectively. According to the stoichiometry of O2− and H2O2 dismutation reactions, it is apparent that about 0.9 to 1.5% of the total oxygen uptake proceeds through the formation of the free intermediates of the partial reduction of oxygen. 相似文献
20.
Summary The influence of the oxygenation level on glucose alcoholic fermentation by free- and immobilized-cell batch cultures ofSaccharomyces cerevisiae (CBS 1200) was investigated. Ethanol production by suspended cultures was stimulated by moderate oxygen flow rates (OFRs) but inhibited by higher OFRs (1.25 mol O2 h–1 dm–3). On the contrary, agar-entrapped yeasts displayed the best fermentation performance under strict anaerobiosis and were less affected than free cultures by high OFRs. These results are dicussed by referring to the substrate mass transfer limitations inherent in immobilized-cell systems. 相似文献