摘要:

AbstractAlginates, both commercial and laboratory made, are strongly fluorescent due to small amounts of polyphenolic materials. These contaminants can be detected by fluorescence spectroscopy in concentrations lower than 1 ppm. This technique has been used to measure polyphenols in a wide range of alginates and various procedures for preparation of biotechnological‐grade alginates have been evaluate

ISSN:0006-3592    

DOI:10.1002/bit.260330112

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe breakage of nylon membrane microcapsules is proposed as a new method to study and quantify shear effects in biological systems. A critique of this method shows that a narrower particle size distribution may be an important improvement in the breakage study as well as breakage control in many bioreactor and biotechnological applications. In a turbine reactor, it was shown that the primary process which determines the microcapsule breakage is the shear effect. The breakage kinetics are first order with regard to the microcapsule concentration. The breakage kinetic constant was ob served to be dependent on the temperature and the particle size, and proportional to the average shear rate and the third power of the turbine angular velocity. Decrease of the breakage kinetic constant with temperature can be explained by a decrease of fluid viscosity and a change in nylon membrane properties. An increase in the breakage kinetic constant with the microcapsule diameter can be due to a lowering of internal pressure and a reduction of the membrane resistance with size. Proportionality between the breakage kinetic constant and the shear rate shows that shear is the main process which leads to microcapsule breakage. The additional intervention in the shear rate expression of the turbine angular speed in the form of the turbine and particle velocities, results in the dependence of the breakage kinetic constant on the third power of the angular velocity.

ISSN:0006-3592    

DOI:10.1002/bit.260330113

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

年代:1989

数据来源: WILEY

摘要:

AbstractTwo novel, nitrogen‐limited and oxygen‐limited, perturbed transient experiments were performed to examine the presence of active transport of methanol and study the effect on methanol uptake by a methanol‐utilizing bacterium,L3, in a batch bioreactor. Transient limitations of both ammonium ions and O2in batch cultures were found to cause methanol leakages out of the cells, suggesting the presence of an active transport of methanol inL3. Such experimental results were used to indirectly estimate the intracellular levels of methanol during a batch growth ofL3. The results of our analysis indicate that the intracellular methanol level is high and show an increasing trend during the unbalanced phase, but falls to a constant low level in the balanced phase of a typical batch growth8ofL3. A simple modelling analysis suggests that a four‐parameter “pump‐and‐extrusion” model could be used to adequately describe the transport of methanol between the extra cellular and intracellular phases of batc

ISSN:0006-3592    

DOI:10.1002/bit.260330114

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

年代:1989

数据来源: WILEY

摘要:

AbstractAn algorithm for operating a fed‐batch fermentor at an optimum specific fermentation rate is proposed. It does not require on‐line measurement of nutrient concentration in the culture medium. An on‐line estimate of the specific fermentation rate is sufficient for implementation of this scheme. The algorithm is model independent and works well even with poor estimates of the product yields and the specific fermentation rate. Results of a detailed simulation study are presented for a simple case of optimization of cell‐mass production in a fed‐batch fermentor. The results clearly demonstrate the efficacy of this algorithm under a wide range of fermentation s

ISSN:0006-3592    

DOI:10.1002/bit.260330115

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

年代:1989

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260330116

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

年代:1989

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260330117

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

年代:1989

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260330101

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

年代:1989

数据来源: WILEY