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