[en] We investigate the possible range of the isotopic ratios of carbon and nitrogen in the mixture of different layers of supernovae with Z Z_[odot] and Z = 0.1Z_[odot]. We carry out the postprocessing nucleosynthesis calculations using the evolution profile of 4 M_[odot] He stars and that of the following supernova explosions to obtain abundance distributions. Main difference due to the metallicity is found in the range of the isotopic ratios of the mixture between the He/C-layer and the He/N-layer. Most of the isotopic ratios of SiC type X grains are inside the range of the isotopic ratios of the mixture between the He/C-layer and the He/N- or Si/S-layer of the supernova models