In Fig. 3 the variations in the specific growth rates of recombinant E. coli
during cultivation in a 2.5-l stirred tank reactor at different AFA concentrations are shown. With SLM54474 the specific growth rate decreased with
increasing AFA concentration, but with S184, VP1133 and S9 no change of m
was observed below 250 ppm AFA concentration. In addition, the number of
cells which were able to propagate (colony forming units CFU) and the CO 2
production rate CPR were determined as a function of the cultivation time
for all four AFAs. The results of these measurements are in good agreement.
They decrease with increasing SLM54474 concentration and with SE9 their
highest values were obtained for 5000 ppm AFA. The AFA concentration did
not influence them up to 500 ppm AFA with S184 and VP1133, but above
that they decreased. The specific product activity (SPA) was the highest at high
SE9 concentrations. With other AFAs no clear concentration dependence was
observed.
208
K. Schügerl
Fig. 2 c, d c specific gas/liquid interfacial area, and d oxygen transfer rate (OTR) and volumetric mass transfer coefficient k L a of oxygen
c
d