4D homogeneous isotropic cosmological models generated by the 5D vacuum

4-dimensional homogeneous isotropic cosmological models obtained from solutions of vacuum 5-dimensional. Einstein equations are considered. It is assumed, that the G(55)-component of the 5D metric simulates matter in the comoving frame of reference. The observable 4D metric is defined up to conformal transformations of the metric of the 4D section <(g)over tilde (mu nu)> with a conformal factor as a function of the component G(55) It is demonstrated, that the form of this function determines the matter equation of state. Possible equations of state are analyzed separately for flat, open and closed models.