Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Publisher
Years
  • 1
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The optimum pH conditions of Pb2+ accumulation in Saccharomyces cerevisiae and Aureobasidium pullulans were 4∼5 and 6∼7, respectively. The initial Pb2+ accumulation rates according to the increase of initial Pb2+ concentration and pH were increased both in S. cerevisie and A. pullulans. And the initial Pb2+ accumulation rate of A. pullulans was much higher than that of S. cerevisiae because of the difference of Pb2+ accumulation mechanism. The Pb2+ accumulation isotherm of S. cerevisae obeyed a fully competitive inhibition, whereas that of A. pullulans showed a mixed inhibition of competition and non-competition associated with the proton (H+) as an accumulation inhibitor.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A perfusion-control strategy based on cellular consumption rates of oxygen and glucose was established for the production of single-chain urokinase-type plasminogen activator (scu-PA). Employing this strategy, the influences of microcarrier types and the culture media on culture performances were evaluated. In the control perfusion culture, which used a solid microcarrier and a 1% fetal bovine serum (FBS) medium, viable cell density reached 3.1 × 107 cells ml−1. However, formation of large, heterogeneous aggregates (500–1,000 μm) resulted in a gradual decrease in viable cell density to less than 1.0 × 107 cells ml−1. Accordingly, declines in the production of urokinase-type plasminogen activator (u-PA) and in the scu-PA portion of u-PA were observed. In the serum-free media, cell growth and u-PA production were suppressed 2–3 times, but were significantly enhanced when a porous microcarrier, Cultispheer G, was used. The cell-growth profile showed a continuous increase in cell density, reaching 5.1 × 107 cells ml−1, and the production of u-PA remained stable throughout the culture (1586 ± 247 IU ml−1). The values of all the parameters associated with cell growth and u-PA production were fairly comparable to or even higher than those in the control culture. Moreover, a 13% higher scu-PA portion of u-PA was observed in the serum-free culture, regardless of the microcarrier type, compared with scu-PA portion of u-PA in the control culture.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Several carrier materials were examined for endoinulinase immobilization. A polystyrene carrier material (UF93®) gave the best immobilization capacity (217 units/g carrier) and operational stability. Carbohydrate compositions in the reaction product were quite similar irrespective of the support materials even though each carrier material has different pore structure associated with diffusional restriction. After immobilization the optimal pH for enzyme activity was shifted from 5.0 to 4.5, whereas optimal temperature (55 °C) was unaltered. Continuous production of inulo-oligosaccharides from chicory juice was carried out using the polystyrene-bound endoinulinase. The recommended operating conditions of the enzyme reactor for maximizing productivity were as follows: feed concentration, 100 g/l chicory juice; flow rate, as superficial space velocity 2.0 h−1; temperature, 55 °C. The enzyme reactor was run for 28 days at 55 °C achieving an oligosaccharide yield of 82% without any significant loss of initial enzyme activity, where the volumetric productivity was 200 g/l · h. Furthermore, there was no marked difference in operational stability between the two reactors fed with pure inulin solution and with chicory juice as a substrate even though chicory juice contains a lot of impurities.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In Pb2+ accumulation by Aureobasidium pullulans, the time to reach an equilibrium state was not dependent on the initial cell dry weight. The Pb2+ accumulation capacity was increased from 56.9 to 215.6 mg Pb2+/g cell dry weight as the biomass was stored from 1 to 53 days, and correlated with the amount of excreted extracellular polymeric substances (EPS). It was observed that Pb2+ accumulated only on the surface of the intact cells of A. pullulans due to the existence of EPS, whereas Pb2+ penetrated into the inner cellular parts of the EPS-extracted cells.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To utilize intracellular endoinulinase for inulo-oligosaccharide (IOS) production from inulin, the endoinulinase gene (inu1) of Pseudomonas sp. was successfully cloned into the plasmid pBR322 by using EcoRI restriction endoinulinase and E. coli HB101 as a host strain. The endoinulinase from E. coli HB101/pKMG50 was constitutively expressed, showing similar reaction modes as compared to those of the original strain. However, some critical differences existed in optimal reaction conditions and oligosaccharide compositions between the two products catalyzed by the native enzyme of original strain and those by intact cells from recombinant cells. The IOS compositions produced by recombinant E. coli were quite different due to the diffusional restriction of the substrate and products within the cell wall. Optimal reaction conditions for batchwise production of IOS were as follow : optimum temperature, 55 °C; pH, 7.5; substrate concentration, 100 g/l inulin; enzyme dosage, 20 units/g substrate. Continuous production of IOS from inulin was also carried out at 50 °C using a bioreactor packed with the recombinant cells immobilized on calcium alginate gel. The optimal feed concentration and the feed flow rate were 100 g/l inulin and 0.6 h−1 as a superficial space velocity, respectively. Under the optimum operation conditions, continuous production of IOS was successfully performed with productivity of 166.7 g/l·h for 15 days at 50 °C without significant loss of initial activity.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In order to increase the synthesis of bovine growth hormone (bGH) using T7 promoter system in E. coli, the artificial AT-rich block was introduced into the upstream region of a consensus Shine-Dalgarno (SD) sequence and the spacer region (between SD and ATG codon) was enriched with A and T nucleotides. The cells harboring pTAJ plasmids with AT-rich block produced bGH in the range of 3% to 25% and the cells harboring pTBJ plasmids with AT-rich sequence in the spacer region from 0.8% to 20% of total cell proteins. This result suggests that AT rich block and AT nucleotides in the spacer region destabilize mRNA secondary structure, depending on the downstream coding information of bGH gene and also, implying that the disruption of mRNA secondary structure might be a major factor for regulating bGH expression in the translational initiation process.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0178-515X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  A new bacterium producing a novel transfructosylating enzyme was isolated from soil and designated as Bacillus macerans EG-6. Various culture conditions for enzyme production were optimized in a flask culture. 1% (w/v) sucrose as a carbon source and a mixed nitrogen source (1% yeast extract, 1% polypeptone, and 0.5% ammonium chloride) gave the best enzyme production. Addition of phosphate and magnesium ion into the medium enhanced the enzyme yield. Optimum culture pH and temperature were 7.0 and 37 °C, respectively. Under optimal culture conditions, transfructosylating enzyme was rapidly produced in the early growth period, thereafter invertase activity was predominant as the culture proceeded. Using the culture filtrate, production of fructooligosaccharides from sucrose was preliminarily carried out. In a low sucrose concentration (200 g/l), transfructosylating activity competes with invertase activity in sucrose utilization. Subsequently, low fructooligosaccharide yield (20%) was achieved due to liberation of high amounts of glucose and fructose. The best oligosaccharide yield (43%) was achieved when 500 g/l sucrose was utilized.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have obtained an overall gene expression profile of a human fetal liver by sequencing the 5′ ends of random cDNA clones from an unbiased cDNA library. As a result, many novel genes that might be related to liver growth and hemopoiesis have been identified. Poly (A)+ RNA was purified from the liver of a human fetus obtained at the 22nd week of gestation, and a directional library was constructed with oligo d(T)-primed cDNAs synthesized without any normalizing procedures. The 5′ end of each randomly chosen clone was sequenced by the dideoxy-chain termination methods, and each sequence was used for homology search in the public databases such as GenBank, SWISS-PROT, and PIR. Of 1231 random cDNA clones analyzed, 697 clones representing 204 different transcripts (57%), were identical to previously known human genes. The spectrum of the genes in this category reflected well the physiological characteristics of the fetal liver, a combination of hepatic and hemopoietic functions. About 4% of the clones represented novel gene transcripts with significant homologies to known genes of human or other organisms. These included several genes that are known to be involved in cellular differentiation and/or proliferation. About 25% of the clones had no statistically significant match to any known genes. In summary, we have identified 546 different gene transcripts consisting of 204 known human genes, 42 homologous genes, and 300 unknown genes. Thus, this approach appears to be a highly efficient way to identify novel genes of biological interest.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...