  It is shown that a Bose-Fermi mixture of a degenerate gas of spin-polarized
fermions, whose number significantly exceeds the number of bosons, embedded in
a strongly anisotropic trap, is described by the one-dimensional coupled
nonlinear Schrodinger equation for the boson component and the wave equation
with external source for the fermion component. Depending on the type of
boson-fermion interaction, the system may display modulational instability and
the existence of solitons in the fermion and boson components respectively.
Such solitons represent either a local decrease (increase) of the density of
both the components or a decrease of the density in one component and an
increase of the density in the other component. It is shown that the type of
the effective interactions can be easily managed by varying the trap geometry
or by means of Feshbach resonance.
