We derive the evolution of the linear bias factor, b(z), in cosmological models driven by an exotic fluid with an equation of state px = wx, where -1 w < 0 (quintessence). Our aim is to put constrains on different cosmological and biasing models by combining the recent observational clustering results of optical (2dF) galaxies (Hawkins et al.) with those predicted by the models. We find that when fitted to the 2dF clustering results, our bias model predicts different bias evolution for different values of w. The models that provide the weak biasing (b0 1.1) of optical galaxies found in many recent observational studies are flat, m = 0.3 with w -0.9. These models, however, predict a weak redshift evolution of b(z), not corroborated by N-body simulations.