  The confinement/deconfinement transition described the
Polyakov-Nambu-Jona-Lasinio (PNJL) model is extended to be operative at zero
temperature regime. In this study, the scalar and vector channel interaction
strengths of the original PNJL model are modified by introducing a dependence
on the traced Polyakov loop. In such a way the effective interactions depend on
the quark phase and in turn provides a backreaction of the quarks to the
gluonic sector, also at zero temperature. On general grounds from quantum
chromodynamics this is an expected feature. The thermodynamics of the extended
model (PNJL0) is studied in detail. It presents along with a suitable choice of
the Polyakov potential, a first order confined/deconfined quark phase
transition even at $T=0$. We also show that the vector channel plays an
important role in order to allow $\Phi\ne0$ solutions for the PNJL0 model.
Furthermore, the sensitivity of the combined quarkyonic and deconfinement
phases to the vector interaction strength and the proposed parametrization of
the Polyakov-loop potential at $T=0$ allowed to set a window for the bulk
values of the relevant parameters.
