摘要:

AbstractContinuous protein separations were performed using a magnetically stabilized fluidized bed (MSFB) and a commercially available affinity adsorption resin that contained no magnetically susceptible material. These nonmagnetic materials can be stabilized at relatively low fields (<75 G requiring<30 W) if sufficient magnetically susceptible particles are also present in the stabilized bed. The minimum amount of magnetic particles necessary to stabilize the bed is as low as 20% by volume and is a function of various parameters including the size and density of both particles, the magnetic field strength, and the fluidization velocity. Advantages of these beds for performing separations include true continuous, countercurrent liquid‐solids contact, mass‐transfer efficiencies nearly equal to that of packed beds, and the ability of handle suspended cells or cell debris. A variety of commercially available affinity, ion‐exchange, and adsorptive supports can be used in the bed for continuous separations; results are presented for the adsorption and recovery of lysozyme from an aqueous mixture of lysozyme and myoglobin using an affinity

ISSN:0006-3592    

DOI:10.1002/bit.260380902

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

年代:1991

数据来源: WILEY

摘要:

AbstractA clonal derivative of a transfectant of the SP2/O myeloma cell line producing a chimeric monoclonal antibody was maintained in steady‐state, continuous culture at dilution rates ranging from 0.21 to 1.04 day−1. The steady‐state values for nonviable and total cell concentrations increased as the dilution rate decreased, while the viable cell concentration was roughly independent of the dilution rate. At steady state, the specific growth rate increased and the specific death rate decreased as the dilution rate increased. The maximum specific growth rate was 1.15 day−1. Antibody production was growth associated and the specific rate of antibody production increased linearly as the specific growth rate in

ISSN:0006-3592    

DOI:10.1002/bit.260380903

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

年代:1991

数据来源: WILEY

摘要:

AbstractA novel method has been developed for the separation of bioproducts from yeast cells. The method uses a combination of physical, chemical, and biological agents such as lytic enzymes, osmotic supports, and spheroplast stabilizers. Using this technique, products (proteins and enzymes) can be released from specific cell locations at different process states; it has thus been celled differential product release (DPR). The wall‐associated proteins are released first and the lytic enzyme is removed together with the wall proteins at this stage. Secondly, the cytosol products are released by a mild procedure during which the organelles remained intact. Finally, the organelle proteins are solubilized. In each stage, specific proteins are released while others are kept inside the different cell compartments. This method can be used with relatively high yeast concentrations (up to 145 g dry wt/L) and gives higher product recoveries and much higher selectivity than mechanical disruptio

ISSN:0006-3592    

DOI:10.1002/bit.260380904

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

年代:1991

数据来源: WILEY

摘要:

AbstractWe report the partition coefficient,Kp′at the isoelectric point of lysozyme, chymotrypsinogen A, albumin, transferrin, and catalase in 64 different polyethylene(PEG)/ dextran(Dx)/water systems. We study the trends of the partition coefficient with protein type, polymer concentration, and polymer molecular weight. We find that the partition coefficient decreases with increasing tie line length for lysozyme, albumin, transferrin, and catalase for whichKpis less than 1, but increases for chymotrysinogen for whichKpis larger than 1. The effect of the tie line length on the partition coefficient is larger for the large proteins than for the small proteins. The partition coefficient decreases with increasing protein molecular weight except for lysozyme suggesting that lysozyme is present as a dimer or a trimer. The partition coefficient decreases with increasing PEG molecular weight, but the magnitude of the increase is larger for the smaller PEG molecular eights and tends to level of at high PEG molecular weight. The partition coefficient increases with increasing dextran (Dx) molecular weight for chymotrypsinogen but decreases for catalase. The partition coefficients of lysozyme, albumin, and transferrin increase with increasing Dx molecular weight from Dx 104to Dx 1.1 × 105and then slightly decrease from Dx 1.1 × 105to Dx 5 × 105. The experimental results are analyzed using a statistical thermodynamics model. The experimental results are analyzed using a statistical thermodynamics model. The experiments suggest that protein partitioning at the isoelectric point in aqueous two‐phase systems is strongly related to the size of the proteins and polymers. Finally, the impossibility of obtaining data completely independent of polymer concentration is emph

ISSN:0006-3592    

DOI:10.1002/bit.260380905

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe profiles of photon flux density incidented on a tubularloop photobioreactor in the day could be altered by inclining the bioreactor at an angle with the horizontal. The photon flux density at noon decreased with increasing angle of inclination, whereas the photon flux density in the early morning and late afternoon increased with increasing angle of inclination. The overall photosynthetic radiance received by the bioreactor inclined at 0, 25, 45, and 80° was 1:0.89:0.77:0.62. Regardless of the angle of bioreactor inclination, the overall biomass output rate of a fed‐batch culture over an 8‐h/day period was comparable (26–36 g‐biomass m−2bioreactor surface area day−1). As a bioreactor inclined at an angle occupied smaller land area, and daily biomass output rate per land area of a bioreactor inclined at 80° (130 g‐biomass m−2land) was about six times of that obtainable at horizontal position (21‐g biomass m−2land). The bioenergetics growth yield from the absorbed photosynthetic radiance was not a constant but an inverse function of the photon flux density. The quasi‐steady state chlorophyll content of theChlorellacells varied between 36 and 63 mg g−1cells. Photoinhibition of the maximum photosynthetic capacity was n

ISSN:0006-3592    

DOI:10.1002/bit.260380906

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe stability of the serine proteases fromBacillus amyloliquefaciens(subtillisin BPN') andBacillus licheniformis(subtilisin Carlsberg) was investigated in various anhydrous solvents at 45°C. The half‐life of subtilisin BPN' in dimethyl‐formamide dramatically depends on the pH of the aqueous solutions from which the enzyme was lyophilized, increasing from 48 min to 20 h when the pH is raised from 6.0 to 7.9. Both subtilisins exhibited substantial inactivation during multihour incubations intert‐amylalcohol and acetonitrile when enzymatic activities were also measured in these solvents; however, when the enzymes were assayed in water instead, hardly any loss of activity was detected. This surprising difference appears to stem from the partitioning of the bound water essential for catalytic activity from the enzymes into the solvents. When assayed in organic solvents, this time‐dependent stripping of water results in decay of enzymatic activity; however, when assayed in water, where the dehydrated subtilisins can undergo rehydration thereby recovering catalytic activity, little inactivation is observed. In agreement with this hypothesis, the addition of small quantities of watertert‐amylalcohol stabilized the subtilisins in it even when enzymatic activity was measured in the nonaqueous solvent. Ester substrates (vinyl butyrate and trichloroethyl butyrate) greatly enhanced the stability of both subtilisins in organic solvents possibly because of the formation of the ac

ISSN:0006-3592    

DOI:10.1002/bit.260380907

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

年代:1991

数据来源: WILEY

摘要:

AbstractContinuous monitoring of concentration is important in the optimal control of bioreactors. Spectrophotometry provides a simple, accurate, and rapid way for measuring cell concentration of unicellular microorganisms, based on either Beer's law or calibration curves prepared using standard solutions. However, this method is limited to a low range of microbial concentrations, because Beer's law deviates significantly at high concentrations. In the present investigation, based on experimental work, a new technique is posed to monitor the concentration of microbial cells as high as 100 g DW/L. this is achieved by using a mixture of known concentration as reference, rather than the “ideal blank” with zero concentration of analyte. As a result, a new equation is developed that, although applied here only to microbial concentration, in principle can be used for monitoring the concentration of any optically sensitive mater

ISSN:0006-3592    

DOI:10.1002/bit.260380908

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

年代:1991

数据来源: WILEY

摘要:

AbstractIn connection with our work on polyelectrolyte complex formation with polyampholytes, the interaction between invertase and several linear polyelectorlytes has been investigated by means of turbidimetry, light scattering measurements, and determination of the enzyme activity. Polyelectrolyte complex formation of invertase was shown to occur with cationic polyelectrolytes only. The light‐scattering data yield information on aggregation and desegregation processes in complex formation. As indicated by our results, only a part of the protein molecules is engaged in this Coulombic interaction, and this part shows a rather small enzyme activity only. Thus, a direct interaction between invertase and a cationic polyelectrolyte is no effective approach to enzyme binding, but a complete immobilization of invertase can be achieved via an “inclusion flocculation” with a symplex formed by interaction between an anionic and a cationic linear polyelectrolyte or via immobilization in symplex microcap

ISSN:0006-3592    

DOI:10.1002/bit.260380909

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

年代:1991

数据来源: WILEY

摘要:

AbstractA hybridoma cell line, AFP‐27‐P, was cultivated in continuous culture under glucose‐limited conditions. The viable cell concentration, dead‐cell concentration, and cell volume all varied with the dilution rate. A model previously developed for a nonproducing clone of the same cell line, AFP‐27‐NP, was extended to describe the behavior of the cells. The relationship between the specific growth rate and glucose concentration is described by a function similar to the Monod model. A threshold glucose concentration and a minimum specific growth rate are incorporated; the model is meaningful only at glucose concentration and a minimum specific growth rate are incorporated; the model is meaningful only at glucose concentrations and specific growth rates above these levels. The relationship between the death rate and the glucose concentration is described by an inverted Monod‐type function. Furthermore, the yield coefficient based on glucose is constant in the lower range of specific growth rates and changes to a new constant value in the upper range of specific growth rates. No maintenance term for glucose consumption is used; in the plot of specific glucose consumption rate vs. specific growth rate, the line intercepts the specific growth rate at a value close to the minimum growth rate. The productivity of antibody as a function of the specific growth rate is described by a mixed type model with a noon‐growth‐associated term and a negative‐growth‐associated term. The values for the model parameters were determined from regression analysis of

ISSN:0006-3592    

DOI:10.1002/bit.260380910

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

年代:1991

数据来源: WILEY

摘要:

AbstractNorlaundanosoline is a key intermediate in the synthesis of the benzylisoquinoline alkaloids providing the upper isoquinoline portion of the morphinanskeleton. This study evaluates the feasibility of usingAspergillus nigeras an in situ biotransformation system to produce norlaudanosoline from dopamine.A. nigerwas chosen because monoamine oxidase can be readily induced in this organism. Monoamine oxidase catalyzes the conversion of dopamine to 3,4‐dihydroxyphenylacetaldehyde. In the presence of dopamine, this aldehyde will then undergo a spontaneous Picket‐Spengler condensation to form norlaudanosoline. Fermentation condition to form norlaudanosoline. Fermentation conditions were optimized for the production monoamine oxidase by using a two‐stage process consisting of a growth stage and an induction stage. pH control was found to be important, and at pH 4.5 dopamine accumulation in the cells was high as was the level of monoamine oxidase. With pH control at 4.5, up to 21% of the cellular dopamine was converted to norlaudanosoline. It is proposed that with further protein engineering improvements, this system may prove suitable for the in situ bio‐transformation of dopamine to norlaudan

ISSN:0006-3592    

DOI:10.1002/bit.260380911

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

年代:1991

数据来源: WILEY