摘要:

AbstractThe use of another air operated extreme pressure hydraulic pump fitted with either a needle valve or a simple microbore tube is described, together with the figures obtained for the soluble protein released from suspensions of commercially obtained baker's yeast (Saccharomyces cerevisiae). The theory of the mechanism is also discussed.

ISSN:0006-3592    

DOI:10.1002/bit.260170402

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

年代:1975

数据来源: WILEY

摘要:

AbstractUsing whole cell invertase ofSaccharomyces pastorianus, entrapped in spherical agar pellets, sucrose hydrolysis was carried out in a continuously fed fluidized bed reactor. The effective rate of reaction determined experimentally for the catalytic pellet was correlated with particle radius (R), intraparticle concentration of enzyme (Ep) and external concentration of substrate (SR).The results were elucidated by theoretical analysis incorporating internal mass transfer resistance. At high degrees of diffusional resistance, the effectiveness factor was successfully estimted from Bischoff's equation. A dimensionless number,mAR(k2Ep/KmD)0.5(Km/(Km+SR)), was used conveniently to predict the effectiveness factor in those cases wher the intraparticle diffusional effect was less significant. This number was employed to determine critical pellet size for an optimal reaction.The relationship between the properties of the pellet (size and intraparticle enzyme activity) and its apparent kinetic constants (k′2andK′m), estimated according to Lineweaver‐Burk, are di

ISSN:0006-3592    

DOI:10.1002/bit.260170403

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

年代:1975

数据来源: WILEY

摘要:

AbstractA modified dynamic method is introduced to determine the oxygen transfer coefficient,KLa, in aerobic fermentation systems which are not mechanically agitated. The dissolved oxygen concentration is measured continuously following a step down or a step up in aeration rate. The response curve is analyzed to obtain the value ofKLaExperiments were carried out at several different air flow rates using mixed culture in concurrent tower fermentors with motionless mixers. The effect of sieve trays and Koch motionless mixers on oxygen transfer was investigated using a 3 in. diameter column. The values ofKLaobtained at the bottom of each column were found to be higher than those obtained at the top. Comparison of the results showed that the values ofKLa were higher when the Koch mixers were used than when the sieve trays were employed.The oxygen uptake rate by the organismsrX, is also calculated by using theKLa values obtained. They compare favorably withthe experimentally measured values.

ISSN:0006-3592    

DOI:10.1002/bit.260170404

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

年代:1975

数据来源: WILEY

摘要:

AbstractElectrochemical regeneration of the cofactor nicotinamide adenine dinucleotide (NAD) from its reduced form (NADH) has been coupled with the alcoholdehydrogenation reaction which consumes NAD and produces NADU using alcohol dehydrogenase bound to alumina. Alcohol (reactant) is added directly to the system while aldehyde (product) leaves the system through an ultrafiltration membrane which prevents loss of the cofactor. This system provides a continuous‐flow process for carrying out a cofactor‐requiring enzymatic reaction with no net loss or consumption of enzyme or cofactor and without the use of reagents for regenerating the cofactor. Although the process shown here is not economically practical, it may be a harbinger of useful and technically feasible chemical reaction systems based on immobilized enzymes requiring cofact

ISSN:0006-3592    

DOI:10.1002/bit.260170405

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe dynamic characteristic of dissolved oxygen probes is usually modeled as being equivalent to a single diffusion layer. Other workers have shown that in response to a downstep in oxygen tension a polarographic probe initially follows single diffusion layer dynamics but that during the last 10% of response the probe deviates significantly from this behavior.Probe response to a series of downsteps of various magnitudes after exposure to calibration gases for 1, 2, and 3 min was recorded. When the probe membrane was new the response behavior was found to be largely independent of the step size as well as the exposure duration.The deviation fro the single diffusion layer model was explained in terms of lateral diffusion of oxygen from the anodic compartment to the cathode. By use of a model incorporating the lateral diffusion, probe response to a general oxygen tension‐time function was calculate

ISSN:0006-3592    

DOI:10.1002/bit.260170406

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

年代:1975

数据来源: WILEY

摘要:

AbstractA nondimensionalized plot, obtained by normalizing the drop‐size distribution in the hydrocarbon phase using the Sauter mean diameter, shows a tendency towards self‐preservation of the distribution. Changes of distribution in time during the course of fermentation, initial dispersed phase fraction, speed of rotation, and reactor size were taken into account. Using this self‐preserving property, an empirical (single parameter) equation has been proposed for drop‐size distribution. Data, available from the literature, are presented for non‐biological and biological systems (gas‐oil,n‐hexadecane, andn‐hexadecane dissolved in dewaxed gas oil as dispersed phases). The parameter, Sauter mean diameter, has been correlated with the operating conditions, and a critical review presented. Cell density was found to have significant effect on Sauter mean diameter. This effect has also been empirically explained. The possibilities of using generalized distribution in predicting the performance of ferment

ISSN:0006-3592    

DOI:10.1002/bit.260170407

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

年代:1975

数据来源: WILEY

摘要:

AbstractOf the experimental methods available for obtaining data to estimate the biological kinetic parameters μm,Ks, andYeach requires considerable experimental effort, yet often yields somewhat imprecise estimates of the parameters, particularlyKs. Therefore it would be worthwhile to seek ways to get parameter estimates of greater precision using less experimental effort. The precision of parameter estimates is strongly dependent, upon the settings of the independent, variables used in the experiments. This dependence is explained and an attempt made to show how experimental settings can be determined that lead efficiently to precise parameter estimates with minimal effort

ISSN:0006-3592    

DOI:10.1002/bit.260170408

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

年代:1975

数据来源: WILEY

摘要:

AbstractBiokinetic parameters are usually calculated from slopes and intercepts taken from plots of experimental data. One response at an item is plotted and used for parameter estimation. Aside from problems that may be caused by transformations made when the data are plotted, this approach has the weakness of not using all the data simultaneously when there is more than one response. This paper shows how multiresponse biological data can be handled to get parameter estimates that are much more precise than those obtained using conventional methods.

ISSN:0006-3592    

DOI:10.1002/bit.260170409

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

年代:1975

数据来源: WILEY

摘要:

AbstractMilk‐clotting enzymes such as pepsin, chymosin, chymotrypsin, andM. mieheiproteases were immobilized on porous, alkylamine glass and incorporated into a fluidized‐bed continuous coagulation scheme. Only pepsin and calf rennet retained sufficient activity towards skim milk to warrant further studies. Comparison of kinetic data with fixed‐bed reactors revealed the overall superior performance of fluidized beds; higher clotting activities were possible while avoiding plugging problems and high pressure drops common to fixed‐bed reactors. Film diffusion and catalyst back‐mixing appear to be significant factors in the overall kinetics.All enzymes lost activity on exposure to skim milk. The inactivation rates were lower at high substrate pH and insignificantly affected by reactor temperature. Nitrogen and sialic acid accumulation on the porous glass paralleled the loss in activity in the initial stages. Attempts to regenerate the immobilized enzymes were partially s

ISSN:0006-3592    

DOI:10.1002/bit.260170410

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

年代:1975

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260170411

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

年代:1975

数据来源: WILEY