  We investigate the quark backreaction on the Polyakov loop and its impact on
the thermodynamics of quantum chromodynamics. The dynamics of the gluons
generating the Polyakov-loop potential is altered by the presence of dynamical
quarks. However, this backreaction of the quarks has not yet been taken into
account in Polyakov-loop extended model studies. In the present work, we show
within a 2+1 flavour Polyakov-quark-meson model that a quark-improved
Polyakov-loop potential leads to a smoother transition between the
low-temperature hadronic phase and the high-temperature quark-gluon plasma
phase. In particular, we discuss the dependence of our results on the remaining
uncertainties that are the critical temperature and the parametrisation of the
Polyakov-loop potential as well as the mass of the sigma-meson.
