  The path integral formulation is given to obtain quark and antiquark
distribution functions in the nucleon within the flavor SU(3) version of the
chiral quark soliton model. The basic model action is a straightforward
generalization of the corresponding SU(2) one, except for one distinguishable
feature, i.e. the presence of the SU(3) symmetry breaking term arising from the
sizably large mass difference $\Delta m_s$ between the strange and nonstrange
quarks. We treat this SU(3) symmetry breaking effect by relying upon the first
order perturbation theory in the mass parameter $\Delta m_s$. We also address
to the problem of ordering ambiguity of the relevant collective space
operators, which arises in the evaluation of the parton distribution functions
at the subleading order of $1/N_c$ expansion.
