Abstract
Biofilm models are commonly used as simulation tools in engineering applications and as research tools to identify and fill gaps in our knowledge of biofilm processes. While models used in engineering applications rely on simplifying assumptions to make them practical, recent experimental evidence of biofilm heterogeneity questions the validity of these assumptions. On the other hand, research models are becoming more complex and use advanced computational tools to mathematically investigate which factors determine the structural heterogeneity and the population dynamics of biofilms. One of the goals of advanced models is to evaluate the relevance of three-dimensional heterogeneities to the predictive capability of traditional biofilm models. In addition, biofilm models are used to evaluate experimental observations when studying a diversity of biofilm-related phenomena. Given the variety of applications of biofilm models and the different approaches that modelers have taken in recent years, a specialist group was convened to evaluate the present status and determine future directions of biofilm modeling research. The education of scientists and engineers on the fundamentals of biofilm models, the development of mathematical models for real-time control of biofilm processes, and the ability to "engineer" the biofilm structure and function (or performance) were identified as the most important objectives 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 microorganisms, the elucidation of attachment and detachment mechanisms, the determination of mechanical properties of exopolymeric substances, and the study of ecological interactions among different microorganisms. The need to evaluate parameter sensitivity in the different models was identified as an essential component of modeling research. A group decision from this meeting was to initiate a collaborative effort to identify similarities and differences among current modeling approaches. Such comparative analysis will enhance our understanding of biofilm processes and mathematical approaches, and will facilitate the future use of biofilm models by scientists and engineers involved in biofilm research.