摘要:

AbstractA growth model forClaviceps purpureain submerged batch culture is presented. In developing the model, the basic principles of the growth and the morphological properties ofC. purpureaare considered. The growth ofC. purpureais assumed to occur in a three‐step manner; the first step involves the assimilation and the growth of cells; the second one involves cell division, and the third one involves transformation of the mature cells to a state where they have no ability to divide but do have the ability to produce ergot alkaloids and then they gradually die. Inorganic phosphate is assumed to be the limiting substrate for the first and the second steps in conditions of carbon source being in excess. The model constants are determined by model simulation and graphical searching techniques to find the minimum value of the absolute difference between the experimental and the simulated curves for biomass, alkaloids, and sucros

ISSN:0006-3592    

DOI:10.1002/bit.260220202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractTwo types of polyethylenimine‐coated glass microbeads (13–44 μm) were synthesized and used for the immobilization of glucose oxidase fromAspergillus nigerand catalase fromA. nigerand beef liver. The two types of beads were distinguishable by differences in their surface topography. Immobilizations were performed by adsorption followed by treatment with glutaraldehyde. The immobilized‐enzyme activities per unit support of all of the enzymes tested were compared with and found to be superior to the immobilized activities attainable on aminopropyl‐activated glass microbeads. When enzyme was present in less than saturating amounts, the coated beads were able to remove 100% of the glucose oxidase activity initially present in the immobilization solution, with 78–87% of that activity expressed on the support surface. Bound glucose oxidase was more stable to thermal inactivation than nat

ISSN:0006-3592    

DOI:10.1002/bit.260220203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractUsing continuous and fed‐batch penicillin fermentation systems some important metabolic parameters have been determined for the purpose of achieving process improvement and better process control. The specific uptake rates determined under the optimal conditions are: 0.33 mmol hexose/g cell/hr, 1.6 mmol oxygen/g cell/hr, 2mg NH3‐nitrogen/g cell/hr, 0.6 mg PO4‐phosphorus/g cell/hr, 2.8 mg SO4‐sulfur/g cell/hr, 1.8 mg phenyl acetic acid/g cell/hr. It was also found that during the production phase, or idiophase, the specific growth rate should be maintained at about 0.015 hr−1in order to support the maximum penicillin productivity of the given strain. Based on the results of this study a significant process improvement has been achieved through proper control of the supply and demand of the important nutrients a

ISSN:0006-3592    

DOI:10.1002/bit.260220204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractAn enzyme electrode is described for quantitative determination of phenol at micromolar concentrations. Immobilized phenol hydroxylase is attached to the surface of a Clark oxygen electrode. The Maximum rate of oxygen consumption is linearly dependent on phenol concentration over the 0.5–50μMrange. The electrode can be used for at least 150 assays without an activity loss. Readout is very rapid—within 30 sec of sample addition. The electrode response is independent of pH between pH 6.5 and 9.5. The response increases linearly with temperature in the interval 10–40°C. It is necessary to incubate the enzyme electrode in a buffer containing NADPH for a few minutes before the addition of sample. This is to make the electrode response independent of the diffusion rate of this cosubstrate. This and other diffusional effects on the performance of the phenol electrode are di

ISSN:0006-3592    

DOI:10.1002/bit.260220205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

Abstractβ‐Galactosidase and other enzymes were immobilized onp‐amino‐carbanilated derivatives of cellulose and methylol cellulose using the diazo method and through glutaraldehyde. The optimum conditions for coupling cellulose tri‐(p‐amino‐carbanilate) (CTAC) to β‐galactosidase were established. The diazo coupling method with CTAC gave greater activity than with glutaraldehyde when coupled to β‐galactosidase (Escherichia coli). The stability of the CTAC–β‐galactosidase system was examined. The disubstitutedp‐amino‐carbanilate derivative (CDAC) gave a lower activity, whereas the methylol analog (MCTAC) gave slightly greater activity. The CTAC was also used to immobilize glucose oxidase,

ISSN:0006-3592    

DOI:10.1002/bit.260220206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractEnzyme stability studies have been reinvestigated under the conditions used for cellulose hydrolysis (pH 4.8, 50°C, 24 hr). The cellobiohydrolase (CBH) component as measured on Avicel is less stable than other enzymes of the cellulase complex, and is 60% inactivated bymerthiolate(and other Hg compounds) under the above conditions. Endo‐β‐1,4‐glucanase is much more stable, and more resistant to merthiolate and other compounds. Under unshaken conditions the Avicelase of the Rutgers strain C 30 shows greater stability to heat than that of other available strains. Biocides must be selected not only for their ability to prevent contamination, but also for their compatibility with cellulases. Tetracycline and chlortetracycline are inexpensive, effective in very low concentrations, have no harmful effect on the enzymes, and are compatible with the yeasts that subsequently grow on the sugar solutions to produce alcohol. Attempts have been made to stabilize the enzymes by chemical modification in such a way as to maintain their solubility. Glutaraldehyde treatment greatly increased the enzyme size, lowered the pIvalues, and gave a slight shift in the pH activity curve. There was, unfortunately,noincrease in enzyme stability, and the activity of enzymes on solid celluloses was adversely affected. Shaking greatly reduced the hydrolysis of Avicel byTrichoderma reeseiC 30 enzyme. The adverse effect was accompanied by a decrease in recoverable enzyme and

ISSN:0006-3592    

DOI:10.1002/bit.260220207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractChemostat cultures of carrot suspension cultures, where growth was limited by the concentration of phosphate in the input medium, were achieved by replacing a fixed proportion of the culture with fresh medium at daily intervals. In the range 0.05–0.30mMphosphate in the input medium and at a specific growth rate of 0.357 days−1, steady‐state culture density but not anthocyanin in the cells was strictly proportional to the input phosphate concentration with no intercept. At a phosphate concentration of 0.10mMand growth rates from 0.105 to 0.430 days−1, the steady‐state culture density could not be described by Monod's model of chemostat cultures, but could be described by Nyholm's model. The steady‐state levels of anthocyanin were not strictly proportional to the steady‐state biomass under all conditions, showing that anthocyanin production is not completely grow

ISSN:0006-3592    

DOI:10.1002/bit.260220208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractBacteria grown on methanol exhibit a poor efficiency of energy conservation, which is mainly due to the low P/O ratio of 1 associated with methanol oxidation. Thermodynamic considerations indicate that a P/O ratio of at least 2 is possible for this step in substrate oxidation. This low efficiency of energy conservation is reflected in the yield values on methanol, which are very important in the consideration of biomass production from methanol. Unfortunately in continuous culture there is no obvious way to select for organisms with a greater efficiency of energy conservation.

ISSN:0006-3592    

DOI:10.1002/bit.260220209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractWhite‐rot fungi, which have the ability to degrade all the wood components including lignin, are of great interest in biotechnological processes based on wood and other lignocellulosic materials. It was demonstrated earlier that enough lignin can be degraded to cause a decrease in the energy demand for production of thermomechanical pulp if wood chips are pretreated by cellulaseless mutants of white‐rot fungi. This paper concerns the growth conditions in wood for three white‐rot fungi and their cellulaseless mutants in order to determine optimal conditions for such pretreatment processes. The pH and temperature optima have been determined as well as the growth rate in wood. The results show that the growth rate in wood. at least for Cel 44 (a cellulaseless mutant ofSporotrichum pulverulentum), is not the rate‐limiting step in delignification. From different mixtures of urea and NH4H2PO4the optimal nitrogen source was determined for the mutants. The optimal C/N ratio was found to vary between 160/1 and 400/1. It is suggested that the lower the C/N ratio, the faster the growth. It was also demonstrated that both water‐ and acetone‐extractable substances in wood supported the growth of cellulaseless mutants. When some glucose was added to the wood, the weight loss caused by Cel 44 increased. All these observations support earlier findings that lignin in wood cannot be degraded by white‐rot fungi unless a more easily metabolizable carbon source is used s

ISSN:0006-3592    

DOI:10.1002/bit.260220210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe hydrophobic interaction of β‐galactosidase with Sepharose 4B substituted with 3,3′‐diaminodipropylamine was studied in both batch and column experiments. The equilibrium and the binding rate constants were determined for different phosphate buffer concentrations. The equilibrium constants exhibit a hysteresis effect, i.e., desorption constants are less than adsorption constants, and the higher the ionic strength to start the desorption, the larger the effect. The rate data are not satisfactorily described by a simple reversible first‐order model. The column chromatographic data are semiquantitatively described by a local equilibrium theory without axial dispersion or intraparticle d

ISSN:0006-3592    

DOI:10.1002/bit.260220211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY