Let (M N , g, e −f dv) be a complete smooth metric measure space with ∞-Bakry-Émery Ricci tensor bounded from below. We derive elliptic gradient estimates for positive solutions of a weighted nonlinear parabolic equationwhere (x, t) ∈ M N × (−∞, ∞) and α is an arbitrary constant. As Applications we prove a Liouville-type theorem for positive ancient solutions and Harnacktype inequalities for positive bounded solutions. 1.2. Smooth metric measure spaces. A smooth metric measure space is denoted by the triple (M N , g, e −f dv), where (M N , g) is an N-dimensional complete manifold with the Riemannian metric tensor g, volume element dv and f is a C ∞ real-valued function on M. Smooth metric measure spaces are naturally endowed with analogue of Laplace-Beltrami operator, called weighted Laplacian and analogue of Ricci tensor, called Bakry-Émery tensor. The weighted Laplacian defined by ∆ f := ∆ − ∇f, ∇· , where ∆ is the Laplace-Beltrami operator, is symmetric and self-adjoint with respect to the weighted measure e −f dv. The m-Bakry-Émery tensor is defined by Ric m f := Ric + ∇ 2 f − 1 m df ⊗ df for some constant m > 0, where Ric is the Ricci tensor of the manifold and ∇ 2 is the Hessian with respect to the metric g. When m is infinite we have the ∞-Bakry-Émery tensor Ric f = lim m→∞ Ric m f := Ric + ∇ 2 f. This tensor is related to the gradient Ricci solitonwhere λ is a real constant. A Ricci soliton is said to be shrinking, steady or expanding depending on whether λ is positive, zero or negative respectively. Ricci