The ability to predict the behavior of fermentation systems enhances the possibility of optimizing their performance. Mathematical equations of model systems represent a tool for this and the most recent advances in computer hardware and software have made the approach more effective than previous simplistic attempts. The current knowledge of biochemical microbial pathways and the experience in optimization of chemical reactors combined with extremely powerful and accessible computers, loaded with easy to use software and mathematical routines, are changing the way processes are being developed and operated. This book has been written for all those who work with microbial cultures, providing a useful, quick and contemporary re-education for practitioners and students alike, breaking through interdisciplinary barriers. Biologists, engineers and biochemists will benefit from the methods of microbial process description and optimization based on mathematical equations. The basic techniques of modeling the bio-system are summarized in Part I. The useful concept of mass balancing is introduced in Part II for those who are not used to this simple and very useful engineering tool. An extensive and descriptive case study of a selected fermentation bio-process in Part III elucidates further the concepts of very pragmatic mathematical modeling of bioreactor systems. The volume outlines how to simply develop mathematical models of microbial systems and demonstrates their power to: guide and minimize the experimental work; check the consistency of experimental results; predict the behavior of the bio-system and analyze biocatalytic processes; diagnose the anomalies in the microbial culture behavior and optimize the performance of bioreactors.