Biomedical Engineering Reference
In-Depth Information
gkg
1
,the
major product was 2,3-butanediol. Therefore, by controlling the DO concentration,
3-hydroxyacetone can convert into 2,3-butanediol or 2,3-butanediol converts into
3-hydroxyacetone in a reversible manner.
Beronio and Tsao [
79
] further studied the effect of oxygen transmission rate
on
K. oxytoca
batch fermentation to produce 2,3-butanediol. The study showed
that the fermentation process can be divided into two stages: the energy-coupling
growth stage and energy-uncoupling growth stage. In the energy-coupling growth
stage, the growth of bacterial cells is coupled with the amount of oxygen; the
maximum yield of 2,3-butanediol could be obtained at this stage, and the energy
growth only occurred when the DO concentration reached a certain limit. By
constantly increasing the partial pressure of oxygen in the gas pass to control the
oxygen mass transfer coefficient, the DO level could be maintained constant, so
the growth of
K. oxytoca
could be maintained in an equilibrium state and the major
by-product of ethanol in 2,3-butanediol production could be suppressed. In addition,
the ventilation quantity not only affected the yield of 2,3-butanediol but also affected
the optical activity of the final product 2,3-butanediol in some certain strains.
Nakashimada et al. [
80
] found that increasing the supply amount of oxygen
reduced the meso-type 2,3-butanediol ratio and thus significantly increased the ratio
of D-type 2,3-butanediol (2R, 3R) in
P. polymyxa
culture. Therefore, the yield of
2,3-butanediol can be controlled by adjusting the amount of oxygen supply in the
fermentation process. The amount of oxygen in the bacterial cells that can be used in
the fermentation process depends on the DO level of the fermentation liquid, while
the DO level can be regulated by the oxygen pressure in the gas phase (oxygen
ratio), so the partial pressure of oxygen can be used as the control parameters in
the fermentation process. Syu and Hou [
81
] predicted the kinetic parameters in the
fermentation process of
K. oxytoca
with the neural network and studied how to
effectively use the neural network to control the fermentation process under different
oxygen pressure conditions.
In short, the discovery and related research of 2,3-butanediol has been conducted
for nearly 100 years around the world. Mainly because of the economic problems
of production costs, most productions remain at the laboratory or pilot stage in spite
of significant progress in all aspects of the production process.
3-hydroxyacetone, and when the DO concentration was below 100
7.4.3.3
Status of Butanediol Fermentation
There are many strains used for 2,3-butanediol fermentation in nature, and that pro-
vides a larger choice of strains. But, because 2,3-butanediol belongs to the primary
product of the bacterial metabolism, its production is limited, and the maximum
theoretical yield is 0.50 g
g
1
glucose. As shown in Table
7.1
, the transformation
the fermentation of many strains has reached a high level, and the 2,3-butanediol
fermentation process basically has reached the level of the alcohol industry interna-
tionally.
