Biofilm modeling: Present status and future directions

Biofilm models are commonly used as simulation tools in engineering applica tions and as research tools to identify and fill gaps in our knowledge of b iofilm processes. While models used in engineering applications rely on sim plifying assumptions to make them practical, recent experimental evidence o f biofilm heterogeneity questions the validity of these assumptions. On the other band, research models are becoming more complex and use advanced com putational tools to mathematically investigate which factors determine the structural heterogeneity and the population dynamics of biofilms. One of th e goals of advanced models is to evaluate the relevance of three-dimensiona l heterogeneities to the predictive capability of traditional biofilm model s. In addition, biofilm models are used to evaluate experimental observatio ns when studying a diversity of biofilm-related phenomena. Given the variet y of applications of biofilm models and the different approaches that model ers have taken in recent years, a specialist group was convened to evaluate the present status and determine future directions of biofilm modeling res earch. The education of scientists and engineers on the fundamentals of bio film models, the development of mathematical models for real-time control o f biofilm processes, and the ability to "engineer" the biofilm structure an d function (or performance) were identified as the most important objective s for the practical application of biofilm models. As mathematical research tools, biofilm models are directed towards gaining a better understanding of biofilm structure and population dynamics. Specific topics identified as priorities on biofilm research include the behavior of specialist microorg anisms, the elucidation of attachment and detachment mechanisms, the determ ination of mechanical properties of exopolymeric substances, and the study of ecological interactions among different microorganisms. The need to eval uate parameter sensitivity in the different models was identified as an ess ential component of modeling research. A group decision from this meeting w as to initiate a collaborative effort to identify similarities and differen ces among current modeling approaches. Such comparative analysis will enhan ce our understanding of biofilm processes and mathematical approaches, and will facilitate the future use of biofilm models by scientists and engineer s involved in biofilm research. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.