Sponges are sources of various useful natural products. The natural compounds derived from sponges are mostly complex polyketide. The polyketide synthase genes (PKS) is responsible for the biosynthesis of complex polyketides. During this research, we detected ketosynthasc (KS) gene domain from 10 species of marine sponges, collected from Mediterranean Sea (Aplysina aerophoba, Petrocia ficiformi…