Comment on "Two-loop calculation of the turbulent Prandtl number"

We have revised the value of the turbulent Prandtl number obtained in the model of a passive scalar advected by the velocity field driven by the stochastic Navier-Stokes equation which was calculated by L. Ts. Adzhemyan et al. [Phys. Rev. E 71, 056311 (2005)] by using the field-theoretic renormalization group approach within the two-loop approximation in the corresponding perturbative theory. It is shown that the correct two-loop contribution to the turbulent Prandtl number is essentially smaller than that calculated by Adzhemyan et al. and, as a result, the final two-loop value of the turbulent Prandtl number is Pr-t=0.7051 instead of Pr-t=0.7693. The source of discrepancy between our result and that obtained by Adzhemyan et al. is identified and discussed.