Biochemical Reaction Networks
127
Table
5.1 Experim entally determ ined values o f TxATP and /ns for various m icroorganism s grow n under
anaerobic conditions w ith glucose as the energy source.
M icroorganism
T iA T P
/Идтр
R e fere n ce
(mmoles ATP
(mmoles ATP
(s
DWVh
(2 DW hV'l
Aerobacter aerogenes
71
6.8
S toutham er and B ettenhaussen (1976)
57
2.3
S toutham er and B ettenhaussen (1976)
Escherichia coli
97
18.9
H em pfling and M ainzer (1975)
Lactobacillus casei
41
1.5
de V ries
et al.
(1970)
Lactobacillus delbruckii
72
0
M ajor and B ull (1985)
Lactococcus cremoris
73
1.4
O tto
etal.
(1980)
53
-
B row n and C ollins (1977)
B enthin
et al.
( 19 94)rf
15-50
7-18
Lactococcus diacetilactis
47
-
B row n and C ollins (1977)
Saccharomvces cerevisiae
71-91
< 1
V erduvn
et al.
(1990)
1
In their analysis, Benthin
et al.
(1994) found a large variation in the energetic parameters depending on the
medium composition, see Example 5.2.
ГЛТР
У xATP
A "b
m ATP
(5-6)
Here rATp specifies the total formation rate of ATP in catabolic pathways (different from the net
formation rate o f ATP, which is implicitly assumed to be zero in the equation). From precise
measurements of the metabolic products of the anaerobic metabolism it is possible to calculate the
specific formation rate of ATP, i.e., rAXP. This may be used to find experimental values for TxAPP and
mATP, as shown in many studies, e.g., Benthin
et al.
(1994) for lactic acid bacteria. In aerobic
processes a major part of the ATP formation originates in the respiration, and the yield of ATP in
this process is given by the P/О ratio. As discussed in Section 4.3 it is difficult to estimate the
operational value of the P/О ratio. Detailed empirical studies, e.g., van Gulik and Heijnen (1995).
have indicated an operational P/О ratio of 1.2-1.3, but this will depend on the microorganism and
perhaps also on the environmental conditions. The ATP production can therefore not be calculated
with the same accuracy in organisms that gain ATP by respiration as for organisms that are only
able to produce ATP in fermentative pathways (substrate level phosphorylation).
In Table 5.1 experimentally determined values for 7xAT? and mATP are collected for a number of
microorganisms growing at anaerobic conditions where /*ATP could be precisely determined. There is
a large variation in the experimentally found values. This is explained by the fact that УхДТР depends
both on the applied medium and on the macromolecular composition of the biomass, as illustrated
by the lower values obtained with growth on a complex medium compared with growth on a
minimal medium.
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