摘要:

AbstractExperimental runs on the inversion of sucrose by means of immobilized β‐fructooxidase are reported. External mass‐transfer and axial dispersion phenomena have been analyzed. It has been observed that external mass‐transfer plays a significative role in the overall kinetics, while axial dispersion phenomena are negl

ISSN:0006-3592    

DOI:10.1002/bit.260250602

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

年代:1983

数据来源: WILEY

摘要:

AbstractMicrobiological transformation of benzaldehyde accomplished by the fungusRhodotorula mucilaginosaimmobilized in the ultrafiltration cell was studied. A polysulfone membrane formed on a sintered PVC support was used for the separation of the transformation product from the cellular material. Kinetic investigations have led to results which are typical of continuously fed stirred tank reactors (CFSTR)—the value of the maximum reaction rate (Vmax) and apparent Michaelis constant (K′m) are practically independent of the substrate retention time (calculated in terms of the flow intensity value). A strong relationship was found to occur betweenVmaxand biomass concentration in the reactor. Study of the apparent enzyme stability shows that the decrease in the biocatalyst activity is chiefly caused by penetration of the cells through the membrane. The experimental results were approximated in terms of the adopted mathematical model. Based on this model, the half‐lives (t1/2) of enzyme activities were determined. Thet1/2value varies from 35 to 82 days and depends both on the permeate flux through the membrane and on the separation properties of the mem

ISSN:0006-3592    

DOI:10.1002/bit.260250603

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis article deals with the effects of the initial concentration of effector (inhibitor or activator) on the steady‐state approximation of enzyme kinetics. The results could be summarized as follows: (1) In competitive inhibition, the increase in the initial concentration of inhibitor led to the reduction of steady state time. (2) In noncompetitive and uncompetitive inhibitions, the steady state time was not changed with the increase in the initial concentration of inhibitor. (3) In nonessential activation, the increase in the initial concentration of activator led to the reduction of steadystate time. (4) It was specially noted that in nonessential activation, even if the reaction is in the steady‐state, activation constant (KA) can not be determined exactly unless the initial concentration of activator is very sm

ISSN:0006-3592    

DOI:10.1002/bit.260250604

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

年代:1983

数据来源: WILEY

摘要:

AbstractA mathematical model is proposed for the elution of proteins on ion exchange columns by a linear gradient increase and stepwise increase of ionic strength in order to predict relationships between the elution characteristics (the peak position, the peak width, etc.) and the operating conditions (the flow rate, the slope of gradient, etc). This model is in principle based on the continuous‐flow plate theory, in which the protein concentration and ionic strength dependent distibution coefficient between proteins and ion exchangers and zone sperading effects are taken into consideration. The advantage of this model is its simplicity since it requires only two parameters: The distribution coefficient and the number of plates. Since the distribution coefficient of proteins depends on both the protein concentration and ionic strength of the elution buffer, the number of plates should vary with time. However, it is extremely difficult to take into consideration the time‐dependent number of plates. Therefore, we assume that the number of plates is constant and related to that number derived from a mass balance model which includes longitudinal dispersion and gel phase diffusion. On the basis of these assumptions, a method for determining the number of plates by the moment method is presented. Although the dependencies of the peak position and peak width on the slope of linear gradient are predictable by numerical calculations of the present model, simpler methods for prediction of these dependencies are desirable. A graphical method is proposed for prediction of the peak position. For prediction of the peak width, an asymptotic solution is derived from a quasi‐steady‐stat

ISSN:0006-3592    

DOI:10.1002/bit.260250605

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

年代:1983

数据来源: WILEY

摘要:

AbstractA sequential model which describes the kinetic behavior of multilayer immobilized‐enzyme filter reactors for systems obeying the Michaelis‐Menten scheme and various types of inhibition by product and by substrate is proposed. The model was varified experimentaly using a single enzyme‐filter‐substrate system—urease bound to nylon‐filter disks acting on urea—in different buffers to obtain the various inhibi

ISSN:0006-3592    

DOI:10.1002/bit.260250606

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

年代:1983

数据来源: WILEY

摘要:

AbstractAn amount of α‐L‐fucosidase fromT. cornutusliver was copolymerized with glutaraldehyde using bovine serum albumin as the carrier protein. The properties of the native, the soluble enzyme polymer complex, and the insoluble enzyme polymer complex were studied and compared under various conditions of pH, temperature, substrate, and inhibitor concentration. Native α‐L‐fucosidase was heat labile and lost more than 85% of its activity when incubated at 55°C for 5 min. In contrast, under equivalent incubation conditions, both the soluble and the insoluble enzyme polymer complexes exhibited enhanced resistance to thermal inactivation and after 5 min lost only 65 and 40% of their original activity, respectively. Polymerzation also resulted in the shift of pH optima towards the acidic range, a decrease in activation energy and a change in the apparentKmvalues towards thep‐nitrophenyl‐α‐L‐fucop

ISSN:0006-3592    

DOI:10.1002/bit.260250607

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

年代:1983

数据来源: WILEY

摘要:

AbstractCellulose fermentation studies were conducted with a thermotolerant strain ofAspergillus terreus. Batch cultivation ofA. terreususing purified or complex cellulose showed that 80–88% of the available cellulose was utilized in 30–36 h with an average doubling time of 7.5–8.3 h. The protein content in the biomass ranged from 23 to 38%. Semicontinuous cultivation studies, in which 90% of the biomass was withdrawn at the end of growth cycle, indicated that 84% of added cellulose was utilized with the biomass containing 32% crude protein. No loss in cellulose consumption, growth rate, or protein production occurred through two growth cycles. Continuous cultivation ofA. terreusshowed that 78–84% cellulose consumption occurred over growth temperatures ranging from 35 to 45°C. Maximum specific growth rates (0.14 h−1) occurred at 40 and 45°C with a minimum doubling ti

ISSN:0006-3592    

DOI:10.1002/bit.260250608

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

年代:1983

数据来源: WILEY

摘要:

AbstractA biological treatment model with ecosystem adaptation (ESA model) is proposed as a means of describing multicomponent sewage treatment. The distribution of microorganisms which oxidize different components of the pollutant is strongly dependent on organic loading. The model can be used to compute multistep treatment systems with specific microflora at each step.

ISSN:0006-3592    

DOI:10.1002/bit.260250609

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

年代:1983

数据来源: WILEY

摘要:

AbstractTraditional biological treatment models are “deduced” from formal chemical kinetics or dynamics of pure microorganism cultures growth. The best formal models give reasonable approximations of the biological treatment model with an ecosystem adaptation (ESA model). The model presented here explains some features of the biological treatment mechanism that cannot be described by formal mod

ISSN:0006-3592    

DOI:10.1002/bit.260250610

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

年代:1983

数据来源: WILEY

摘要:

AbstractCellulose degradation to methane under continuous fermentation conditions was compared using fully mixed, fully mixed with solids return, sludge‐blanket, and fixed‐film fermenters. In fully mixed fermenters, a decrease in hydraulic retention time (HRT) of two weeks or less caused the wash out of anaerobes capable of converting volatile fatty acids to methane, while at increased feeding rates over 1 g/L day the rapid growth of cellulolytic anaerobes upset the balance between acid formation and its conversion to CH4. Circulation of cellulose and difficulty in settling of cellulose with attached bacteria imposed problems in the use of other types of fermenters. On the basis of information obtained from this study, a fermenter which combined a fully mixed phase for cellulose degradation and a fixed‐film phase with pre‐immobilized bacteria for converting fatty acids to CH4in one vessel, was devised. Using this fermenter, a mixed culture converted cellulose to CH4at 4.8 g/L day at a HRT of six days as compared to 0.7 g/L day at a HRT of 28 days in the fully mixed fe

ISSN:0006-3592    

DOI:10.1002/bit.260250611

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

年代:1983

数据来源: WILEY