E-Book Overview
The contributions to this special volume were selected in order to show present trends in the field of bioprocess monitoring and estimation. Established conventional methods are critically discussed and non-conventional ones introduced. Two papers focus on more fuzzy approaches such as electronic noses or advanced chemometric techniques. One contribution illustrates the high potential with the example of cephalosporin production. Three contributions dare to "look" inside the cells, one by the analysis of (microscopic) images, one by trying to estimate the so-called physiological state, and the third by analyzing the metabolic network. This shows how sophisticated (bio)chemical as well as mathematical analytical tools result in better understanding of living systems and bioprocesses.
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Laudatio
This volume is dedicated to Dr. Armin Fiechter, Professor Emeritus of Biotechnology at the ETH Zürich and former managing editor of Advances in Biochemical Engineering/Biotechnology and Journal of Biotechnology and editor and member of Advisory Boards of several international periodicals on the occasion of his 75th birthday. Armin Fiechter is one of the pioneers in biotechnology – recognized worldwide for his important contributions to various fields of biotechnology. Professor Fiechter’s research covers a broad area. He carried out pioneering work in several fields. From the beginning, he stressed the necessity of interdisciplinary and international cooperation. He especially promoted cooperation between engineering and biological research groups and helped to overcome the hurdles and borders between these groups. His active role as a teacher of young scientists led to the well known “Fiechter School”. Some well-known researchers in industry and science come from his laboratory. His more than 500 publications document his research activities in different areas of biotechnology. The quantitative evaluation of biological regulation was especially difficult, because reproducibility of the measurement of the dynamical processes was unsatisfactory in the 1960s. One of the first long-term continuous cultivation of baker’s yeast in a chemostat system in combination with aseptic operation and use of pH- redox- and oxygen-electrodes was realized by his group. The sterility was obtained by O-ring sealing. The sterilizable pH-, redox- and oxygen electrodes were developed in the industry with his co-operation. The sealing of the stirrer shaft with a sliding sleeve and the use a marine propeller in combination with a draft tube (compact loop reactor, COLOR) for maintaining ideal mixing and for better mechanical foam control was also developed in cooperation with his group. One of the key issue was the better process control by means of in situ monitored pH- and redox-values and dissolved oxygen concentration in the cultivation medium under aseptic operation.Various instruments (FIA, HPLC, GC, MS) were adapted for on-line monitoring of the concentrations of key components and computer programs were developed for automatic data evaluation and control. In this compact loop reactor and by means of advanced measuring and control systems highly reproducible measurements became possible. Professor Fiechter succeeded to show using the improved chemostat technique that glucose and oxygen influence various yeast stains differently. Beside the catabolite repression (glucose effect) a second regulation type exists which is controlled by the dynamic substrate flux (glucose). This causes different types
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Laudatio
of physiological phenomena such as diauxie, secondary monoauxie or atypical changes in growth and ethanol production continuous cultures. Sonnleitner and Kaeppeli in his group developed an overflow model to explain these phenomena. Overflow reaction is common not only in yeast, but in bacteria as well. In add