Section: Overall Objectives

Introduction

Natural or reconstituted microbial ecosystems are often very complex (high diversity, interactions within and between species, coupling with spatial processes: niches, aggregation, biofilm...) [83] .

We bet that simple models (in the sense that they are manageable analytically and/or in a computer) of these ecosystems can explain their main functions, mainly concerning degradation and conversion. For this purpose, we investigate population models both deterministic (differential equations) and stochastic (stochastic differential equations, death-birth processes), as well as individual-based models.

Another challenge is to develop, from expert knowledge and experimental observations, models that are simple enough (i.e. without an exhaustive description of all microbial actors) to carry out model identification and selection as well as the determination of “control laws”, but realistic enough to be validated on real processes within a decision-making perspective (i.e. bioprocess control).

One of the main difficulties is to identify the limits of the validity of these models (especially in terms of population size, and of prediction of the coexistence of species). This requires a proper mathematical analysis as well as the development of adapted simulation tools.