Th. Bley

A modular approach to situation identification of the dynamics of bacterial populations synthesizing poly-β-hydroxybutyrate

Abstract Biotechnological processes involving bacteria are strongly nonlinear. Therefore, both their productivity and the final product quality may be considerably improved by applying appropriate control strategies to modulate behavior of the bacteria during transitional states. This requires advance identification of indicative signals by off-line investigation (i.e. experimental analysis) and on-line monitoring, (i.e. real time evaluation). A modular scheme is presented for doing this, which incorporates an Extended Kalman Filter and a prediction filter. If this is based on a suitable process-feature vector, which must be chosen in advance, the system can provide sufficient information to trigger appropriate feedback signals. Thus, it can provide a key element in modular situation control, allowing continuously periodic process management. In this publication the individual modules involved, and their assembly into an integrated system are described. Potential problems concerning selection of the feature vector, and experimental results are also discussed.

How Should Microbial Life be Quantified to Optimise Bioprocesses

Quantification of microbial life is necessary for optimising bioprocesses. The scientific background of biologists, chemists and engineers, who are engaged in this field, is very specific and therefore the approaches to quantification are extremely different as well. The roots for quantification and the constraints of microbial performance are discussed, and it is shown that only a holistic approach, the approach of systems biology, can lead to satisfactory results. The essential contribution of Wolfgang Babel to this holistic approach is emphasised.