High-performance bioreactors: a new generation

Compact loop bioreactors with a total volume of 4 l were equipped with electrically controllable valves and pumps, most of the currently available on-line sensors, direct digital control systems and a process minicomputer; complete automatic operation was thus achieved. These reactors perform excellently: the mixing time is <1 s, oxygen transfer is not a limiting factor and the precision of control of more than 10 process variables is much better than so far reported on other systems. Such high-performance bioreactors were used in investigating the stable synchronous oscillations of Saccharomyces-type yeasts and the reduction of slightly soluble organic compounds with biocatalysts. The inherent advantages of on-line measurement (and control) are discussed.