Remarks about UV regularization of basic commutators in string theories

The zeta regularization of basic commutators in string theories, recently proposed by Hwang, Marnelius and Saltsidis, is generalized to the string models with non-trivial vacuums. It is shown that implementation of this regularization implies the cancellation of dangerous terms in the commutators between Virasoro generators, which break the Jacobi identity.