MINI-REVIEW Modeling of enzyme production kinetics Mani Thilakavathi & Tanmay Basak & Tapobrata Panda Received: 12 July 2006 / Revised: 30 August 2006 / Accepted: 5 September 2006 / Published online: 23 November 2006 # Springer-Verlag 2006 Abstract Models of single cells, cell populations, and cultures can be most useful in organizing information in a comprehensive system description, as well as in optimizing and controlling actual production operations. Models discussed in this article are of various degrees of biological structure and mathematical complexity. The models are developed based on the biomass formation, substrate consumption, and product formation. The potentials and the limitations of all the models have been reported. The parameter estimation by different methods has been discussed in this communication. These parameters will be helpful to explore the areas where future-modeling studies may be especially valuable. Keywords Enzyme kinetics . Modeling . Parameters estimation . Sensitivity function . Structured model Introduction The analyses of huge amounts of fermentation data are very important. A lot of data are still being added hereto. Data from fermentation studies are highly complex in nature. Hence, the need for methods and tools for data analysis is obvious, both in academic research and in industry where data analysis may be carried out in an inefficient manner. The mathematical treatment of the processes encountered in bioengineering is cumbersome due to the complexity of living systems and the segregated nature of microbial life. Models derived from first engineering principles are potentially important and indispensable in bioreaction engineering. By combining experimental work with math- ematical modeling, it is possible to provide meaningful interpretations of the experimental results to analyze new aspects of microbial physiology. The model can then be used for designing new and more focused experiments (Hjortso and Bailey 1984; Kompala et al. 1986; Nielsen et al. 1991; Seo and Bailey 1985). The modeling of enzyme production kinetics is very difficult and challenges exist at all stages of model development, i.e., model formulation, identification and estimation of the parameters, and solution of the equations (Coppella and Dhurjati 1989). Models of single cells, cell populations, and cultures can be most useful in organizing information in a comprehensive system description, as well as in optimizing and controlling actual production oper- ations (Curien et al. 2003; Grosz and Stephanopoulos 1990a; Rizzi et al. 1996). A few review papers have been published on structured models (Fredrickson et al. 1970; Nielsen and Villadsen 1992; Tziampazis and Sambanis 1994). However, this article reviews the important models used for enzyme production kinetics such as structured model, unstructured model, dynamic model, and cybernetic model. This article focuses on the recent development of models and their applications. Various methods of strategies for solving the model equations are highlighted in this communication. Appl Microbiol Biotechnol (2007) 73:991–1007 DOI 10.1007/s00253-006-0667-0 M. Thilakavathi : T. Panda (*) Biochemical Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600 036 Tamil Nadu, India e-mail: pandaiitm@yahoo.co.in T. Basak Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600 036 Tamil Nadu, India