Predictive Bioinformatics represents a major field of applications for combinatorial optimization techniques. Very often, an ensemble perspective, which not only consider the optimal solution but also fully embraces the set of suboptimal solutions, needs to be adopted. In this Habilitation à Diriger des Recherches, I present a series of algorithmic and combinatorial contributions, inspired by problems and questions arising in the study of RiboNucleic Acids (RNAs), in particular pertaining to their structural properties at the thermodynamic equilibrium.La bioinformatique prédictive représente un domaine majeur d'application pour les techniques d'optimisation combinatoire. Très souvent, une perspective ensembliste, ne se limitant pas à une so...