  Recently, X. Qi and J. Hou [Phys. Rev. A 85, 022334 (2012)] provided optimal
entanglement witnesses without the spanning property. These witnesses are
associated to indecomposable positive linear maps, but it is not checked
whether partial transposes of these witnesses are also optimal. We show that
partial transposes of these entanglement witnesses have spanning property, and
these witnesses are indeed optimal PPTES witnesses (non-decomposable optimal
entanglement witnesses).
