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  • 1
    Electronic Resource
    Electronic Resource
    Xanthan batch fermentations: compared performances of a bubble column and a stirred tank fermentor (1990)
    Springer
    Bioprocess and biosystems engineering 5 (1990), S. 107-114 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Fermentations of Xanthomonas campestris, NRRL B-1459, were carried out in a bubble column fermentor (BCF) and in a stirred tank fermentor (STF) to allow comparison of representative variables measured during the microbial growth and the gum production. The microbial growth phase was described by a logistic rate equation where maximum cell concentration was provided by nitrogenous compounds balance. The average value of the maximum specific growth rate was higher in the bubble column (μ M =0.5 h−1) than in the stirred reactor (μ M =0.4 h−1). The upper values of xanthan yield (Y g-x =0.65 kg xanthan/kg glucose; Y O 2−x xanthan/kg oxygen) and specific production rate (q x =0.26 kg xanthan/kg biomass · h) were measured when the oxygen transfer coefficient was kept up above 80 h−1 in the STF fermentor. In the bubble column the fermentation achieved in the same culture medium lasts two times longer than in the stirred aerated tank; this was attributed to the low value of the oxygen transfer coefficient (K L a =20 h−1) at the beginning of the gum synthesis phase. The results obtained in the stirred tank were the basis to estimate the optimal biomass concentration which enables to achieve a culture in non-limiting oxygen transfer conditions. Nevertheless, the transfer characteristics were more homogeneous in the bubble column than in the stirred tank where dead stagnant zones were observed. This is of primary importance when establishing fermentation kinetics models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388188
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  • 2
    Electronic Resource
    Electronic Resource
    An Improvement of the Cell Diffusion Method for the Rapid Determination of Diffusion Constants in Gels or Foods (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 54 (1989), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A diffusion cell was designed to study the apparent diffusion coefficient of solutes through foodstuffs. The mathematical model corresponding to the experimental setup did not assume quasi-steady state diffusion within the slice of food. It was used to obtain the effective diffusion coefficient of NaCl through 3% Agar gels. The results were compared to those obtained by using two agar gel cylinders at different concentrations. The diffusion coefficient of Cl− in gel at 25°C was obtained with at least the same precision (D = 1.30 × 10−9 m2/sec, SD= 0.03 × 10−9 m2/sec) within less than 110 min compared to a few hours with the two cylinder technique. With the mathematical model used to determine diffusion coefficients, the equilibrium ratio between solute concentration in solution and at the interface of foodstuff can be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1989.tb08593.x
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of the behavior of penicillium roquefortii in solid state cultivation on support by material balances
    Amsterdam : Elsevier
    Journal of Fermentation and Bioengineering 74 (1992), S. 305-311 
    Details
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0922-338X(92)90065-3
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  • 4
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    The Passage of the Sebeto (1838)
    London : Periodicals Archive Online (PAO)
    Bentley's miscellany. 3 (1838) 29 
    Details
    ISSN: 1751-8466
    Topics: Linguistics and Literary Studies
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:8727-1838-003-00-000009
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  • 5
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    The Passage of the Sebeto (1838)
    London : Periodicals Archive Online (PAO)
    Bentley's miscellany. 3 (1838) 29 
    Details
    ISSN: 1751-8466
    Topics: Linguistics and Literary Studies
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:8727-1838-003-00-000009
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  • 6
    Electronic Resource
    Electronic Resource
    Growth and sporulation behaviour of Penicillium roquefortii in solid substrate fermentation: effect of the hydric parameters of the medium (1992)
    Springer
    Applied microbiology and biotechnology 38 (1992), S. 183-187 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Both growth and sporulation increase linearly according to the initial water content of the solid substrate when Penicillium roquefortii is cultivated on buckwheat seeds. This indicates that water is the limiting factor for fungal development since neither carbon nor nitrogen sources were exhausted during these experiments. This feature validates the concept of available water for fungal growth, defined as initial water content of substrate minus its residual water content when vegetative growth stops. An efficient methodology, based on drawing a regression line of mycelium dry weight production as a function of the initial water content of substrate is presented; it allows estimation of both available water and water content of mycelium. Results show that growth stops when the residual water in the substrate is close to 0.52 g H2O/g initial dry matter, corresponding to a water activity (aw) close to 0.96, and that the initial water content in mycelium is near 76%. Thus, both aw and water content of the substrate have to be taken into account during the course of solid-state cultivations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174465
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  • 7
    Electronic Resource
    Electronic Resource
    Fed-batch biotransformation of β-ionone by Aspergillus niger (1995)
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 222-227 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Aspergillus niger IFO 8541 was found to be an efficient biocatalyst for the biotransformation of β-ionone into hydroxy and oxo derivatives. The reaction had to be carried out with an inoculum made of about 4×107 fresh spores/l and with a preliminary growth period giving at least 3 g/l biomass. The fungus developed in the form of pellets when cultivated as free mycelium; entrapment of the microorganism in calcium alginate beads was an efficient way to mimic this feature in an aerated, stirred bioreactor. The biotransformation was carried out using a fed-batch mode of operation involving sequential precursor addition. β-Ionone stopped the fungal growth and was converted into metabolites only when the carbon source remained present in the medium; it was fully oxidized after sucrose exhaustion. These conditions allowed recovery of about 2.5 g/l aroma compounds after 230 h cultivation with a molar yield close to 100%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050394
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  • 8
    Electronic Resource
    Electronic Resource
    Fed-batch biotransformation of β-ionone by Aspergillus niger (1995)
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 222-227 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Aspergillus niger IFO 8541 was found to be an efficient biocatalyst for the biotransformation of β-ionone into hydroxy and oxo derivatives. The reaction had to be carried out with an inoculum made of about 4 × 107 fresh spores/l and with a preliminary growth period giving at least 3 g/l biomass. The fungus developed in the form of pellets when cultivated as free mycelium; entrapment of the microorganism in calcium alginate beads was an efficient way to mimic this feature in an aerated, stirred bioreactor. The biotransformation was carried out using a fed-batch mode of operation involving sequential precursor addition. β-Ionone stopped the fungal growth and was converted into metabolites only when the carbon source remained present in the medium; it was fully oxidized after sucrose exhaustion. These conditions allowed recovery of about 2.5 g/l aroma compounds after 230 h cultivation with a molar yield close to 100%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00172816
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  • 9
    Electronic Resource
    Electronic Resource
    Pyrazine production by Bacillus subtilis in solid-state fermentation on soybeans (1997)
    Springer
    Applied microbiology and biotechnology 47 (1997), S. 489-495 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract 2,5-Dimethylpyrazine (2,5-DMP) and tetramethylpyrazine (TTMP) were produced using Bacillus subtilis IFO 3013 grown on soybeans. Solid-state cultivations were carried out either in 100-ml bottles or in a fixed-bed column reactor, both systems being at 27 °C. Optimization studies showed that the best way to produce the two above aroma compounds involved two separate processes. 2,5-DMP was obtained using soybeans enriched with 75 g threonine/kg initial dry weight (i.d.w.), giving 0.85 g metabolite/kg i.d.w. after 6 days. TTMP production involved addition of 90 g/kg i.d.w. acetoin to soybeans, and 2.5 g/kg i.d.w. was recovered after 14 days. These results demonstrated the suitability of solid-state cultivation for production of high-added-value compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050961
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  • 10
    Electronic Resource
    Electronic Resource
    Sporulation of Penicillium roqueforti in solid substrate fermentation (1984)
    Springer
    Biotechnology letters 6 (1984), S. 97-102 
    Details
    ISSN: 1573-6776
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A study of the influence of temperature, aeration rate, and substrate water content on sporulation of Penicillium roqueforti on buckwheat seeds in a fixed bed reactor is described. Use of an experimental procedure based on a 23 factorial design allowed optimum to be determined as 23.5° C for temperature, 0.48 g/g dry matter for substrate water content and 4.42 VVH for aeration rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00127297
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