  In this paper, we show that there exists a nonconstant CR holomorphic
function of polynomial growth in a complete noncompact Sasakian manifold of
nonnegative pseudohermitian bisectional curvature with the CR maximal volume
growth property. This is the very first step toward the CR analogue of Yau
uniformization conjecture which states that any complete noncompact Sasakian
manifold of positive pseudohermitian bisectional curvature is CR biholomorphic
to the standard Heisenberg group.
