摘要:

AbstractThe estimation of the size of each reactor of a series of CSTR's performing a Michaelis–Menten reaction in the liquid phase can be obtained to advantage via an optimization technique leading to the minimum overall capital cost. The cost scaleup is assumed to be described by a power rule on the equipment capacity. Various contributions are lumped into the exponent, thus leading to values above unity. The analytical development leading to the optimal intermediate concentrations of substrate according to the foregoing criterion is presented. A short‐cut method based on an empirical expression that approximates the numerical solution is reported. This correlation is found to be exact at the asymptotic behaviors, and to give accurate results within an acceptable error level for the range with physical interest. Therefore, it is particularly useful during the predesign steps of equipment for the biochemical indus

ISSN:0006-3592    

DOI:10.1002/bit.260330302

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe balance equations for carbon, reduction potential, and energy during cell growth and product formation are rederived in a general form. Cells are treated simply as a very complex product, and theYATPconcept is extended to products. Limitations on the theoretical yield are discussed for different product types. Simple aerobic products cannot be energy limited unless the maintenance requirement is large, while complex products cannot be reduction limited. A maximum yield is defined for products much more oxidized than their substrate (carbon limited) because the theoretical yield conditions may violate the energy balance. For reduced complex products the yield on available electrons is related toYATP, theP/Oratio, and the product composition. Narrow bounds are established on the actual yields in simple anaerobic fermentations, and the significance of the yields in the linear growth equation is discussed.

ISSN:0006-3592    

DOI:10.1002/bit.260330303

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

年代:1989

数据来源: WILEY

摘要:

AbstractWater activity of the substrate is an important and acute factor for growth as well as for metabolic production of microorganisms or for biocatalyst systems. A sensor has been designed in order to control this parameter on‐line during submerged and solid‐substrate fermentations. This sterilizable sensor allows the measurement of the relative humidity of the atmosphere in a small chamber by means of a capacitive element separated from the medium by a thin ethylenepolytetrafluoride membrane. For highawvalues (>0.90) a sequential circulation of a dried gas prevents the sensor saturation. Measurements are rapid and accurate, and control of the water activity of a fermentation medium has been carried out for 5 days using this sen

ISSN:0006-3592    

DOI:10.1002/bit.260330304

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

年代:1989

数据来源: WILEY

摘要:

AbstractA mathematical model describing the dynamics of foreign protein secretion from yeast cells is developed. The secretion events, which are a series of complicated enzymatic reactions and carrier‐involved transport, are lumped to a practically applicable model structure, based on the major interactions between the heterologous polypeptides and the host cell's secretory machinery through the pathway. The developed model structure predicts that the secretion rate constant is represented as a saturated form with respect to the host cell's specific growth rate. The validity of the proposed model structure is tested by generating dynamic response data to a step input of cycloheximide. The model system used in the experiment is SEY2102‐s21, which has an integrated copy of a yeast secretion‐mutant invertase that simulates well typical gene cassettes designed to secrete mature foreign proteins utilizing the yeast cell's secretion signals. Protein quantification is done by gel electrophoresis followed by immuno‐blot on nitrocellulose filters and subsequent scanning with a reflectance densitometer. Experimental data confirm the proposed model st

ISSN:0006-3592    

DOI:10.1002/bit.260330305

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe control of the continuous, competitive mixed culture of the yeastCandida utilis(ATCC 8205) and the bacteriumEscherichia coliB/r (ATCC 12407) was examined. A modified version of the dynamic matrix control (DMC) algorithm was tested in simulation and then was successfully implemented. This represents the first report of the location and stabilization of a competitive mixed culture at a metastable equilibrium point using automatic control.

ISSN:0006-3592    

DOI:10.1002/bit.260330306

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

年代:1989

数据来源: WILEY

摘要:

AbstractA novel technique has been developed to immobilize plant cells. The cells are deposited on a surface of manmade fibrous material that provides for strong binding of the plant tissue biomass growing in the submerged culture. The immobilized plant cells remain fully viable. Relatively uniform biomass loadings of up to 20 mg d.w. plant cells/cm2support material have been attained. All plant cells from the inoculum suspension became attached within the first 24–48 h depending on the support matrix configuration and hydraulic culture conditions. The advantages and scale‐up potential of this technique are discussed and compared to other culturing mo

ISSN:0006-3592    

DOI:10.1002/bit.260330307

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

年代:1989

数据来源: WILEY

摘要:

AbstractA model of contact‐inhibited growth of cells on flat and spherical surfaces is presented. It shows that contact inhibition does not significantly affect the calculated growth rate of cells unless they are allowed to multiply a large amount from the original seeding density. Microcarriers seeded at low densities require long times to reach confluence because contact inhibition becomes important. In systems with both growth and separate cell death, the equilibrium fraction of holes in the confluent monolayer is below 8% if the death rate is less than half the growth rate, but increases rapidly as the death rate increases from that valu

ISSN:0006-3592    

DOI:10.1002/bit.260330308

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

年代:1989

数据来源: WILEY

摘要:

AbstractImmobilization ofAureobasidium pullulansby adsorption on solid supports and entrapment in open pore polyurethane foam were attempted. By adsorption, the highest cell loading of 0.012–0.018 g dry wt/cm2support was obtained in pH 2.0 medium. Under this acidic condition, the net surface charges (zeta potentials) of both the cells and supports were close to zero and no pullulan was synthesized. Cationic coatings of Cytodex and polyethylenimine were not efficient in enhancing the binding strength between the cells and the supports. Surface immobilized cells and polyurethane foam entrapped cells exhibited a similar fermentation characteristics resulting in ca. 18 g/L pullulan and ca. 5 g/L leaked cells. However, cells entrapped in the polyurethane foam were more shear resistant. The immobilized cells thus could be repeatedly used for pullulan biosynthesi

ISSN:0006-3592    

DOI:10.1002/bit.260330309

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

年代:1989

数据来源: WILEY

摘要:

AbstractA simple growth model is proposed for plant cell aggregates which accounts for leakage of a single intermediate metabolite from the aggregates to the medium. This model predicts a lag phase in the growth curve whose extent is determined by the intermediate metabolite leakage coefficient and its equilibrium distribution coefficient between the medium and the cell aggregates, the size of the inoculum relative to the system total water content, and the initial intermediate metabolite content in the medium. The model thus provides for an interaction between growing plant cells and their environment in a way that has heretofore been unquantified. Preliminary validation of the model has been made against literature data ofDioscorea deltoideagrown in batch suspension cell culture on sucrose, yielding a correlation coefficient of 0.997. The predicted glucose + fructose concentration in the medium agrees reasonably well with experimental measurements after ca, 3.5 days of culture, although a discrepancy exists between model prediction and experiment immediately after startup. Further validation of the model is suggested on this and other plant species.

ISSN:0006-3592    

DOI:10.1002/bit.260330310

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

年代:1989

数据来源: WILEY

摘要:

AbstractA successful procedure for attaching cellulase to 45 μm iron oxide particles with a high‐molecular‐weight (1000) ligand has been developed. Mass and activity balances were calculated for immobilized enzymes with different loadings. The highest specific activity of the immobilized enzyme was 5.9 mmol glucose/g bound protein/h. The efficacy of retaining enzymatic activity was 128%. The optimum pH was 5.5 compared to 4.0 of the free enzyme. The half‐life of the IMC was extended to 272 h compared to 0.77 h of the free

ISSN:0006-3592    

DOI:10.1002/bit.260330311

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

年代:1989

数据来源: WILEY