TY  - RPRT
AU  - Memmert, K.
TI  - Kontinuierliche Xylanaseproduktion mit Bacillus amyloliquefaciens
VL  - 2132
IS  - Juel-2132
CY  - Jülich
PB  - Kernforschungsanlage Jülich, Verlag
M1  - FZJ-2018-02770
M1  - Juel-2132
T2  - Berichte der Kernforschungsanlage Jülich
SP  - VII, 169 p.
PY  - 1987
AB  - Xylanase synthesis in$\textit{Bacillus}$ $\textit{amyloliquefaciens}$ DSM 7 was found to be constitutive but controlled by catabolite repression. This control mechanism caused a declining yield in xylanase production, as soon as the culture reached a steady-state growth in chemostate culture. It could be shown that the catabolite repression of exoenzyme synthesis could be lifted and xylanase production occured, when the bacteria were subject to a defined oxygen limitation. This defined oxygen limitation could be reached by holding the oxygen tension inside narrow limits around 0.5% of saturation. As this range of low oxygen tensions only occured in transient states but never in steady states of continuous cultivation, it had to be fixed by varying the fermenter's stirrer speed thus changing the oxygen transfer rate by an automatic control. As a redox probe generates more accurate values at this range of very low oxygen tensions than a polarographical oxygenelectrode, the culture's redox potential was used as the control signal. Comparative measurements of redox potential and oxygen tension indicated that the redox potential is proportional to the logarithm of the oxygen tension. Holding the redox potential and oxygen tension by control within this unstable non-steady range, a constant high xylanase productivity of about 1000 U/(g$\cdot$h) could be obtained in continuous culture.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)29
UR  - https://juser.fz-juelich.de/record/845543
ER  -