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  • 1
    Electronic Resource
    Electronic Resource
    Interdependence of Gene Expression for Early Steps of Cephalosporin Synthesis in Streptomyces clavuligerus (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 721 (1994), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1994.tb47383.x
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  • 2
    Electronic Resource
    Electronic Resource
    Polystyrene Macroporous Bead Support for Mammalian Cell Culture (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 665 (1992), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1992.tb42581.x
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  • 3
    Electronic Resource
    Electronic Resource
    Transition of outgrowing spores of Bacillus brevis into vegetative cells is not dependent on destruction of gramicidin S (1990)
    Springer
    Applied microbiology and biotechnology 32 (1990), S. 708-710 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Certain Bacillus brevis strains produce gramicidin S (GS) during sporulation, and germination of such spores is delayed at the stage of outgrowth by endogenous or exogenous GS. Claims have been made that the transition from germinating spores into vegetative cells is dependent on GS destruction. We observed no such destruction of either exogenous or endogenous GS. Thus, in our hands, the “recovery” of the inhibited germinating spores must be dependent on something other than GS elimination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164745
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  • 4
    Electronic Resource
    Electronic Resource
    Stimulatory effect of growth in the presence of alcohols on biotransformation of penicillin G into cephalosporin-type antibiotics by resting cells of Streptomyces clavuligerus NP1 (1999)
    Springer
    Applied microbiology and biotechnology 52 (1999), S. 484-488 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Growth of Streptomyces clavuligerus NP1 in the presence of methanol or ethanol resulted in a marked increase in production of cephalosporin(s) from penicillin G by resting cells. The mycelium produced in alcohol-supplemented medium was fragmented and dispersed as compared with growth in control medium. HPLC analysis showed that at least two products were present in the biotransformation supernatant fluid after 1 h incubation. One of them has been identified as deacetoxycephalosporin G (DAOG).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051549
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  • 5
    Electronic Resource
    Electronic Resource
    Production of intracellular serine protease during sporulation of Bacillus brevis ATCC9999 (1983)
    Springer
    Applied microbiology and biotechnology 17 (1983), S. 227-230 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary It has been reported (Slapikoff et al. 1971) that Bacillus brevis ATCC9999, the producer of gramicidin S, makes no extracellular or intracellular protease in complex medium which supports sporulation. We have found that intracellular protease is made by this strain; however, the activity requires the presence of the reducing agent dithiothreitol in the extraction buffer. B. brevis intracellular protease appears at the time that refractile spores are visible in the mother cells. Its pH optimum is 8.0. The enzyme is inhibited by ethylenediaminetetraacetic acid and phenylmethylsulfonylfluoride but not by o-phenanthroline, boronic acids, and only slightly by p-chloromercuribenzoate. This inhibitor pattern is similar to that of intracellular proteases of B. megaterium and B. subtilis, classifying the B. brevis protease as an intracellular seryl protease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00510420
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  • 6
    Electronic Resource
    Electronic Resource
    Cellular determinants affecting the rate of cytokine in cultures of human hematopoietic cells (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 58-66 
    Details
    ISSN: 0006-3592
    Keywords: stem cells ; LTC-IC ; expansion ; cytokine depletion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The present study was undertaken to define parameters that may limit the cytokine-mediated expansion of primitive hematopoietic cells in stirred suspension cultures of normal human marrow cells. In a first series of experiments, parallel measurements of the rate and extent of progenitor expansion and cytokine depletion from the medium were made for such cultures in which the cells were exposed to different cytokine concentrations. Supplementation of the medium with 2 ng/mL of interleukin-3 (IL-3), IL-6 and IL-11 plus 10 ng/mL of Flt-3 ligand (FL) and Steel factor (SF) allowed a 45-fold expansion of directly clonogenic cell (CFC) numbers within 2 weeks along with a 2.5-fold expansion of their precursors, detectable as longterm culture-initiating cells (LTC-IC). The addition of 5-fold higher levels of these cytokines enhanced the 2 week output of both CFC and LTC-IC numbers (to 66-fold and 9-fold above input respectively). However, this was also associated with an increase in the individual average rates of depletion of immunoreactive IL-3, SF and FL. As a result, even biweekly addition of fresh medium supplemented with the highest concentrations of cytokines tested failed to prevent a continuing decline in their levels relative to the input medium levels. A similar dependence of the IL-3 depletion rate on its extracellular concentration was demonstrable in suspension cultures of Mo7e cells, an IL-3-dependent human leukemic cell line.Additional experiments with various highly purified marrow cell fractions showed that the rate of cytokine depletion varied according to the type of responding cell as well as the specific cytokine. CD34+CD38- cells exhibited the greatest average cell-specific cytokine depletion rates (35-fold higher than unseparated bone marrow cells). These findings establish new principles that will be important for the optimization of hematopoietic cell bioreactors. In addition, they suggest that cytokine depletion may provide a novel feedback control mechanism in vivo which would contribute to the control of primitive hematopoietic cell proliferation and differentiation. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 58-66, 1997.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Protein polarization in isotropic membrane hollow-fiber bioreactors (1994)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 40 (1994), S. 321-333 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model has been developed to predict the coupled hydrodynamics and high-molecular-weight protein transport in mammalian-cell hollow-fiber bioreactors (HFBRs). The analysis applies to reactors with isotropic ultrafiltration membranes under startup conditions when the extracapillary space (ECS) is essentially unobstructed by cells. The model confirms the experimental finding that secondary ECS flows, engendered by the primary flow in the fiber lumens, can cause significant downstream polarization of ECS proteins at typical mammalian-cell HFBR operating conditions. It also reveals that the osmotic activity of the proteins, by curtailing transmembrane fluid fluxes, can influence strongly the outcome of the polarization process. In fact, at order-of-magnitude higher protein concentrations and/or lower recycle flow rates, the secondary flow velocities can be reduced by as much as six orders-of-magnitude throughout the ECS, thereby virtually eliminating the polarization problem. This result has important implications for improved reactor startup procedures.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690400211
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  • 8
    Electronic Resource
    Electronic Resource
    Controlled release process to recover heterologous glycosylphosphatidylinositol membrane anchored proteins from CHO cells (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 480-486 
    Details
    ISSN: 0006-3592
    Keywords: CHO ; PI-PLC ; heterologous glipiated proteins ; controlled release ; GPI anchor ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A semicontinuous process has been developed to recover heterologous proteins at increased concentrations and purities. Proteins attached to mammalian cell membranes by glycosylphosphatidylinositol (GPI) anchors can be selectively released into the supernatant by the enzyme phosphatidylinositol-phospholipase C (PI-PLC). Chinese hamster ovary (CHO) cells, genetically engineered to express the GPI anchored, human melanoma antigen (p97), were used as a model system. These cells were grown in protein containing growth medium. During a brief harvesting phase the medium was replaced by phosphate buffered saline (PBS) containing 10 mU/mL of PI-PLC and the GPI anchored protein was cleaved from the cell surface and recovered in soluble form at up to 30% purity. After harvesting, the cells were returned to growth medium where the protein was re-expressed within 40 h. The growth rate, viability, and protein production of cells, repeatedly harvested over a 44-day period, were not adversely affected. This continuous cyclic harvesting process allowed recovery of a heterologous protein at high purity and concentrations and could be applied to the recovery of other GPI anchored proteins and genetically engineered GPI anchored fusion proteins. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420411
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  • 9
    Electronic Resource
    Electronic Resource
    Glycolipid membrane anchored recombinant protein production from CHO cells cultGred on porous microcarriers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 45-54 
    Details
    ISSN: 0006-3592
    Keywords: microcarriers, porous ; melanotransferrin human ; CHO cells ; protein production ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recombinant proteins were harvested from Chinese hamster ovary (CHO) cells by a controlled release process, which increased the purity and concentration of the harvested protein. Recombinant human melano-transferrin (p97) was expressed linked to the outer surface of CHO cells by a glycosyl-phosphatidylinositol (GPI) membrane anchor. Cells were grown to confluence in T-flask culture, and the p97 harvested by replacing the growth medium for 30 min with phosphate-buffered saline (PBS) containing 10 mU/mL phosphatidylinositol-phospholipase C (PI-PLC). The GPI anchor was selectively cleaved by PI-PLC. In fresh medium, the CHO cells regained over 95% of their p97 expression within 40 h. The process was repeated for eight harvests. Harvested protein concentrations varied from 1.5 to 3.8 μg/mL due to difficulties in maintaining stable confluent T-flask cultures. Harvesting from cells growing on porous microcarriers was investigated to increase p97 product concentrations and to overcome culture stability problems. Semicontinuous cultures were maintained in spinners for up to 76 days with average bioreactor cell densities of over 107 cell/mL. The p97 was harvested at up to 100 μg/mL and 30% purity with protein production remaining stable for 4 harvest cycles. Production of high levels of p97 from CHO cells was maintained at 0.5% serum. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440108
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  • 10
    Electronic Resource
    Electronic Resource
    Membrane anchored protein production from spheroid, porous, and solid microcarrier chinese hamster ovary cell cultures (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 550-556 
    Details
    ISSN: 0006-3592
    Keywords: spheroids ; porous and solid microcarriers ; CHO ; controlled release ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of the microcarrier type on the performance of a controlled release process used to produce a recombinant glycosyl-phosphatidylinositol anchored protein was investigated. Chinese hamster ovary (CHO) cells expressing the human melanoma tumor antigen (p97) were cultured in 10% serum on Cultispher-GH porous microcarriers and then, for protein production, maintained in 2% serum. Cells were harvested every 48 h and p97 was recovered at 90 μg/mL and 40% purity. Harvested p97 concentrations were increased by harvestingfrom spheroid (241 μg/mL) and smaller porous microcarrier, Cultispher-G (167 μg/mL) cultures. The low total cell specific p97 production of cells cultured on Cultispher-GH was due to necrosis of cells within the beads, decreased p97 expression of the immobilized cells, dilution by the liquid (up to 40% volume) associated with settled beads, and incomplete recovery of p97 from within the beads. Cells cultured on solid microcarriers, Cytodex-1, had the highest cell viability and cell specific p97 production, It is recommended that a two-stage cyclic harvesting process of cells cultured on small Cultispher-G or on Cytodex-1 beads would minimize protein loss and maximize cell specific protein recovery. © 1995 John Wiley & Sons Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260470507
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