  The B-type pulsators known as \beta Cephei and Slowly Pulsating B (SPB) stars
present pulsations driven by the \kappa mechanism, which operates thanks to an
opacity bump due to the iron group elements. In low-metallicity environments
such as the Magellanic Clouds, \beta Cep and SPB pulsations are not expected.
Nevertheless, recent observations show evidence for the presence of B-type
pulsator candidates in both galaxies. We seek an explanation for the excitation
of \beta Cep and SPB modes in those galaxies by examining basic input physics
in stellar modelling: i) the specific metal mixture of B-type stars in the
Magellanic Clouds; ii) the role of a potential underestimation of stellar
opacities. We first derive the present-day chemical mixtures of B-type stars in
the Magellanic Clouds. Then, we compute stellar models for that metal mixture
and perform a non-adiabatic analysis of these models. In a second approach, we
simulate parametric enhancements of stellar opacities due to different iron
group elements. We then study their effects in models of B stars and their
stability. We find that adopting a representative chemical mixture of B stars
in the Small Magellanic Cloud cannot explain the presence of B-type pulsators
there. An increase of the opacity in the region of the iron-group bump could
drive B-type pulsations, but only if this increase occurs at the temperature
corresponding to the maximum contribution of Ni to this opacity bump. We
recommend an accurate computation of Ni opacity to understand B-type pulsators
in the Small Magellanic Cloud, as well as the frequency domain observed in some
Galactic hybrid \beta Cep-SPB stars.
