  Perturbation theory in the nonperturbative QCD vacuum and the non-Abelian
Stokes theorem, representing a Wilson loop in the SU(2) gluodynamics as an
integral over all the orientations in colour space, are applied to derivation
of the correction to the background-induced string effective action. This
correction is due to accounting in the lowest order of perturbation theory for
the interaction of perturbative gluons with the string world sheet. It occurs
that this interaction affects only the coupling constant of the rigidity term,
while its contribution to the string tension of the Nambu-Goto term vanishes.
The obtained correction to the rigid string coupling constant multiplicatively
depends on the spin of the representation of the Wilson loop under
consideration, the QCD coupling constant and a certain path integral, which
includes the background Wilson average.
