The optimization task was performed using the gluconic acid synthesis
by the Acetobacter methanolicus MB 58 strain. The microorganisms were
grown continuously on methanol as the growth substrate. After finishin
g the growth process by the deficiency of N and P, the gluconic acid s
ynthesis was started by adding glucose. The synthesis process was perf
ormed continuously. The oxygen transfer rate depended on the gluconic
acid concentration. During the growth process, the oxygen transfer rat
e reached a value of about 13 g O2 . kg-1 . h-1 using a 30-1 glass fer
menter equipped with a 6 blade stirrer and fully baffled. This rate de
clined to a value of between 2 and 5 g 02 - kg-1 . h-1 in the presence
of gluconic acid concentrations above 150 g gluconic acid - kg-1 medi
um. The yield (g gluconic acid . g-1 glucose) depended on the gluconic
acid concentration and amounted to y = 0.7 in relation to 150 g gluco
nic acid - kg-1 medium and y = 0.8 in relation to 200 g - kg-1 medium,
respectively. The fermenters were coupled with ultrafiltration moduls
(Fa. ROMICON and Fa. SARTORIUS). The biomass concentrations amounted
from 5 to 40 g dry mass kg-1 medium. The ultrafiltration modules retai
ned the biomass within the fermentation system. A glucose solution (30
to 50 weight percent glucose) was continuously dosed into the ferment
er. The retention time was chosen between 2 and 30 h. The gluconic aci
d synthesis rate reached values of up to 32 g gluconic acid . kg-1 - h
-1. Within a range of up to 250 g gluconic acid . kg-1 medium, the aci
d concentration had no influence on the enzyme activity.