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  • 1
    Electronic Resource
    Electronic Resource
    Glucose as an energy donor in acetate growing Acinetobacter calcoaceticus (1986)
    Springer
    Archives of microbiology 144 (1986), S. 62-66 
    Details
    ISSN: 1432-072X
    Keywords: Acinetobacter calcoaceticus ; Continuous cultivation ; Acetate growth ; Glucose oxidation ; Energy gain ; Maximum carbon conversion efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since glucose can be oxidized but not assimilated by Acinetobacter calcoaceticus 69-V the question arose whether energy generated by glucose oxidation can help incorporate carbon from heterotrophic substrates and, if so, what the efficiency of ATP production is like. For this reason this species was grown in the chemostat on acetate. After having reached steady state conditions an increasing concentration of glucose was added. This led to an increase in the biomass level from about 0.4 g/g for growth on acetate alone to 0.6–0.65 g/g in the presence of glucose, independently of either the growth rate or the steepness of the glucose gradient used. This upper value approximates about the limit of the carbon conversion efficiency calculated for non-glycolytic substrates. Glucose was almost exclusively oxidized to gluconic acid, 2- and 5-ketogluconates, and pentose 5-phosphates were found only in traces. These results demonstrate that glucose functions as an additional energy source in Acinetobacter calcoaceticus 69-V. From the transient behaviour of biomass increase and the mixing proportion at which the maximum growth yield on acetate in the presence of glucose was obtained it followed that two mol of ATP must have been generated per mol of glucose oxidized. This property is discussed in terms of coupling glucose dehydrogenase with the respiratory chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454957
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  • 2
    Electronic Resource
    Electronic Resource
    Improvement of growth yield of yeast on glucose to the maximum by using an additional energy source (1983)
    Springer
    Archives of microbiology 136 (1983), S. 203-208 
    Details
    ISSN: 1432-072X
    Keywords: Maximum growth yield ; Mixed substrate utilization ; Glucose ; Formate ; Transient-state cultivation ; Hansenula polymorpha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The experimentally determined growth yield on glucose under aerobic conditions is approximately 0.5 g/g, but on the basis of the carbon content a value of 0.71 g/g should be the upper limit if carbon conversion is improved by the use of an additional energy source. This assumption was investigated with the methylotrophic yeast Hansenula polymorpha MH 20. Formate served as an additional energy source. The growth yield experiments were performed with a transient-state fermentation technique in which formate was fed via an increasing concentration gradient to a culture growing continuously on glucose. As a result the growth yield on glucose was improve, the extent was dependent on the formate feeding rate, i.e. the slope of this formate gradient. The predicted maximum growth yield of 0.7 g/g was obtained at a slope of the formate gradient of 0.21 g/l·h at a glucose concentration of about 1 g/l. Steeper gradients did not further improve this value, but rather impaired the growth yield due to the appearence of a high residual formate concentration in the fermentation medium. The yield patterns are influenced by the culture pH, a value of at least 4.8 is necessary to achieve the maximum growth yield on glucose. At lower pH formate became increasingly toxic. The ratio of formate to glucose necessary to obtain the maximum yield coefficient was 1...1.6:1 (in grams). On the basis of the energy content of formate a ratio of 1.2...1 (P/O=2) was calculated to substitute the part of glucose which is endoxidized for energy generation. Deviations from this value are explained in terms of the manner of uptake and uncoupling property of formic acid/formate and the existence of a second, formate-“wasting” enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409845
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Flow of 14C-methanol via assimilatory and dissimilatory sequences with yeast in presence of glucose (1985)
    Springer
    Archives of microbiology 143 (1985), S. 77-81 
    Details
    ISSN: 1432-072X
    Keywords: Mixed substrate utilization ; 14C-Methanol glucose ; Efficiency of methanol dissimilation ; Improvement of growth yield ; Hansenula polymorpha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were performed to reveal the extent to which individual heterotrophic substrates of a mixture contribute to the overall carbon and energy metabolism. For this reason Hansenula polymorpha MH 20 was chemostatically (C-limited) cultivated at different growth rates on mixtures of methanol and glucose fed at proportions of 3:1 and 1:3 (in weight units), respectively. The distributions of 14C-carbon from methanol in biomass as well as carbon dioxide (and supernatant) fractions were determined. From these results it followed, firstly, that energy derived from methanol dissimilation was used in part for the incorporation of glucose carbon, resulting in carbon conversion efficiencies for this substrate equivalent to yield coefficients of 0.61–0.69 g/g. Secondly, the growth yield data revealed that the efficiency of methanol conversion had to be increased in order to account for the experimentally determined yield figures. This was further confirmed by theoretical treatment of the growth yield data which showed that these could only be obtained if P/O-quotients for methanol conversion similar to those for glucose, i.e. 2.0–2.5, were considered. The latter property was regarded as the main reason for the observed improvement of growth yield accompanying the simultaneous utilization of methanol and glucose in this yeast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414772
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    Paper (German National Licenses)
    Fulltext
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