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  • 1
    Electronic Resource
    Electronic Resource
    Enzymic hydrolysis of corn gluten meal (1989)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 37 (1989), S. 1188-1192 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00088a081
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  • 2
    Electronic Resource
    Electronic Resource
    Ion exchange immobilization of changed β-galactosidase fusions for lactose hydrolysis (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 745-752 
    Details
    ISSN: 0006-3592
    Keywords: β-galactosidase immobilization ; charged fusions ; whey hydrolysis ; ion exchange ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of charged peptides fused to enzymes for immobilization onto ion-exchange membranes was explored for the enzyme ×-galactosidase. The additional charged peptides, containing 1, 5, 11, and 16 aspartates, fused to ×-galactosidase, for the most part did not interfere with the kinetic behavior for lactose hydrolysis. There was a 2-fold decline in Vm for the 16-aspartate fusion, but the others were quite similar to the wild type enzyme (BGWT). BGWT and the fusions all retained approximately 50% of their activities when adsorbed onto ion-exchange membranes. In contrast to BGWT, the enhanced binding strength of the 11 aspartate fusion provided the ability to hydrolyze whey permeate at 0.3 M ionic strength without enzyme leakage, and to immobilize the enzyme directly from diluted cell extract with 83% purity. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440611
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  • 3
    Electronic Resource
    Electronic Resource
    Broth recycle in a yeast fermentation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1228-1234 
    Details
    ISSN: 0006-3592
    Keywords: broth recycle ; water reuse ; Apiotrichum curvatum ; fermentation ; microbial lipid ; inhibition ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation is a water-intensive process requiring treatment of large amounts of effluent broth. It is desirable to increase the ratio of product produced to the volume of effluent by minimizing the discharge of effluent from the fermentation process. A study of recycling spent fermentation process. A study of recycling spent fermentation broth for the subsequent fermentation was carried out with Apiotrichum curvatum an oleaginous yeast, as the working culture. Spent broth from a defined medium was recycled t replace as much as 75% of the water and salts for subsequent batches and this was repeated for seven sequential batches without affecting cell mass and lipid production. A 64% vlume reduction of wastewater was achieved in this manner. However, when using whey permeate as the medium, lipid production dropped after three consecutive recycle operations at 50% recycle, and after two consecutive recycle operations at 75% and 100% recycle. Accumulation of ions in the broth appeared to be responsible for the inhibition. An ion exchange step was able to eliminate the ion buildup and restore fermentation performance. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260441010
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  • 4
    Electronic Resource
    Electronic Resource
    Genetically engineered charge modifications to enhance protein separation in aqueous two-phase systems: Charge directed partitioning (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 62-68 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; β-galactosidase ; T4 lysozyme ; partitioning ; charge modifications ; genetic engineering ; polymers ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This report continues or examination of the effect of genetically engineered charge modifications on the partitioning behavior of proteins in aqueous two-phase extration. The genetic modifications consisted of the fusion of charged peptide tails to β-galactosidase and charge-change point mutations to T4 lysozyme. Our previous article examined the influence of these charge modifications on partitioning as a function of interfacial potential difference. In this study, we examined charge directed partitioning behavior in PEG/dextran systems containing small amounts of the charged polymers diethylaminoethyl-dextran (DEAE-dextran) or dextran sulfate. The best results were obtained when attractive forces between the protein and polymer were present. Nearly 100% of the β-galactosidase, which carries a net negative charge, partitioned to the DEAE-dextran-rich phase regardless of whether the phase was dextran or PEG. In these cases, cloudiness of the protein-rich phases suggest that strong charge interactions resulted in protein/polymer aggregation, which may have contributed to the extreme partitioning. Unlike the potentialdriven partitioning reported previously, consistent partitioning trends were observed as a result of the fusion tails, with observed shifts in partition coefficient (Kp) of up to 37-fold. However, these changes could not be solely attributed to charge-based interactions. Similarly, T4 lysozyme, carrying a net positive charge, partitioned to the dextran sulfate-containing phase, and displayed four- to sevenfold shifts in Kp as a result of the point mutations. These shifts were two to four times stronger than those observed for potential driven partitioning. Little effect on partitioning was observed when the protein and polymer had the same charge, with the exception of β-galactosidase with polyarginine tails. The high positive charge density of these tails provided for a localized interaction with the dextran sulfate, and resulted in 2- to 15-fold shifts in Kp. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460109
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  • 5
    Electronic Resource
    Electronic Resource
    Genetically engineered charge modifications to enhance protein separation in aqueous two-phase systems: Electrochemical partitioning (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 147-153 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase systems ; β-galactosidase ; T4 lysozyme ; partitioning ; charge modifications ; genetic engineering ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have examined the effect of genetically engineered charge modifications on the partitioning behavior of proteins in dextran/polyethylene glycol two-phase systems containing potassium phosphate. By genetically altering a protein's charge, the role of charge on partitioning can be assessed directly without the need to modify the phase system. The charge modifications used are of two types: Charged tails of polyaspartic acid fused to β-galactosidase and charge-change point mutations of T4 lysozyme which replace positive lysine residues with negative glutamic acids. The partition coefficient Kp for these proteins was related to measured interfacial potential differences Δφ using the simple thermodynamic model, In Kp = In Ko + (F/RT)Zp δφ. The protein net charge Zp was determined using the Henderson-Hasselbalch relationship with modifications based on experimentally determined titration and isoelectric point data. It was found that when the electropartitioning term Zp δφ was varied by changing the pH, the partitioning of T4 lysozyme was quantitatively described by the thermodynamic model. The β-galactosidase fusions displayed qualitative agreement, and although less than predicted, the partitioning increased more than two orders of magnitude for the pH range examined. Changes in the partitioning of lysozyme due to the various mutations agreed qualitatively with the thermodynamic model, but with a smaller than expected dependence on the estimated charge differences. The β-galactosidase fusions, on the other hand, did not display a consistent charge based trend, which is likely due either to the enzyme's large size and complexity or to nonelectrostatic contributions from the tails. The lack of quantitative fit with the model described above suggests that the assumptions made in developing this model are oversimplified. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440202
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  • 6
    Electronic Resource
    Electronic Resource
    Water reuse in the L-lysine fermentation process (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 341-347 
    Details
    ISSN: 0006-3592
    Keywords: water reuse ; fermentation ; lysine ; Corynebacterium glutamicum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: L-Lysine is produced commercially by fermentation. As is typical for fermentation processes, a large amount of liquid waste is generated. To minimize the waste, which is mostly the broth effluent from the cation exchange column used for l-lysine recovery, we investigated a strategy of recycling a large fraction of this broth effluent to the subsequent fermentation. This was done on a labscale process with Corynebacterium glutamicum ATCC 21253 as the l-lysine-producing organism. Broth effluent from a fermentation in a defined medium was able to replace 75% of the water for the subsequent batch; this recycle ratio was maintained for three sequential batches without affecting cell mass and l-lysine production. Broth effluent was recycled at 50% recycle ratio in a fermentation in a complex medium containing beet molasses. The first recycle batch had an 8% lower final l-lysine level, but 8% higher maximum cell mass. In addition to reducing the volume of liquid waste, this recycle strategy has the additional advantage of utilizing the ammonium desorbed from the ion-exchange column as a nitrogen source in the recycle fermentation. The major problem of recycling the effluent from the complex medium was in the cation-exchange operation, where column capacity was 17% lower for the recycle batch. The loss of column capacity probably results from the buildup of cations competing with l-lysine for binding. © 1996 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Propionic acid production by extractive fermentation. I. Solvent considerations (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 454-461 
    Details
    ISSN: 0006-3592
    Keywords: propionic acid ; extractive fermentation ; solvent ; partition ; acid recovery ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Solvent selection for extractive fermentation for propionic acid was conducted with three systems: Alamine 304-1 (trilaurylamine) in 2-octanol, 1-dodecanol, and Witcohol 85 NF (oleyl alcohol). Among them, the solvent containing 2-octanol exhibited the highest partition coefficient in acid extraction, but it was also toxic to propionibacteria. The most solvent-resistant strain among five strains of the microorganism was selected. Solvent toxicity was eliminated via two strategies: entrapment of dissolved toxic solvent in the culture growth medium with vegetable oils such as corn, olive, or soybean oils; or replacement of the toxic 2-octanol with nontoxic Witcohol 85 NF. The complete recovery of acids from the Alamine 304-1/Witcohol 85 NF was also realized with vacuum distillation. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 454-461, 1998.
    Additional Material: 5 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of protein charge to partitioning in aqueous two-phase systems (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 461-470 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase separation ; protein partitioning ; T4 lysozyme ; electrochemical partitioning ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein partitioning in aqueous two-phase systems based on phase-forming polymers is strongly affected by the net charge of the protein, but a thermodynamic description of the charge effects has been hindered by conflicting results. Many of the difficulties could be because of problems in isolating electrochemical effects from other interactions of phase components.We explored charge effects on protein partitioning in poly(ethylene glycol)-dextran two-phase systems by using two series of genetically engineered charge modifications of bacteriophage T4 lysozyme produced in Escherichia coli. The two series, one in the form of charged-fusion tails and the other in the form of charge-change point mutations, provided matching net charges but very different polarity. Partition coefficients of both series were obtained and interfacial potential differences of the phase systems were measured. Multi-angle laser light scattering measurements were also performed to determine second virial coefficients. A semi-empirical model accounting for the roles of both charge and non-charge effects on protein partitioning behavior is proposed, and the results predicted from the model are compared to the results from the experiments. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:461-470, 1998.
    Additional Material: 7 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Charged fusions for selective recovery of β-galactosidase from cell extract using hollow fiber ion-exchange membrane adsorption (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 333-338 
    Details
    ISSN: 0006-3592
    Keywords: purification fusion ; ion exchange ; membrane ; β-galactosidase ; separation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We explored the use of charged fusions for selective recovery of β-galactosidase from cell extract using a low-cost, easily scaled, fast, charge-based separation technique - ion exchange on hollow fiber ion-exchange membranes (HFIEMs). The additional charges carried by a series of anionic fusion tails allowed selective binding and release of β-galactosidase from Escherichia coli cell extract using the HFIEM cartridge. The purification factors increased with fusion length. The β-galactosidase was recovered in active form. For the longest fusion studied, more than sixfold enrichment in specific activity was attained. The specific activity of the recovered fraction is comparable with that of commercial wild-type β-galactosidase and affinity-purified fusion protein. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420310
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  • 10
    Electronic Resource
    Electronic Resource
    The pharmacokinetics of chlortetracycline orally administered to turkeys: Influence of citric acid andPasteurella multocida infection (1985)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 243-264 
    Details
    ISSN: 1573-8744
    Keywords: chlortetracycline (aureomycin) ; citric acid ; pharmacokinetics ; physiological ; turkeys ; fowl cholera ; disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A physiologically based pharmacokinetic model was developed to describe the absorption and disposition of chlortetracyline (CTC) in the healthy and diseased (fowl cholera) turkey. The CTC was given (with and without citric acid) as an oral (15 mg/kg) or i.v. (1 mg/kg) dose. When minerals (0.3 g/LCa2+, 0.1 g/LMg2+) were dissolved in the bird's drinking water, the model indicated that the addition of citric acid (mass ratio of 10 citrate:1 CTC) increased the fraction of dose absorbed from 0.06 to 0.16; once absorbed, the fractions of drug eliminated by renal excretion, biliary secretion, and chemical decomposition were 50, 46, and 4%, respectively. The presence of fowl cholera appeared to increase plasma levels by increasing the intestinal permeability and lowering the hepatic and/or renal clearance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01065655
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