**5. Conclusions**

*Streptomyces* has various systems in order to produce polyketides with different structures and functions. Knowing the polyketide structures, activities, producing enzymes, starter units, extender units, and the structural genes are very important in the development of new drugs. Some mechanisms of polyketide biosynthesis in *Streptomyces* that have been reported previously could provide strong basic knowledge not only for the biosynthesis investigation of the new polyketides, but also engineering the producing system in the future.

**Acknowledgments:** The authors gratefully acknowledge support from German Federal Ministry of Education and Research (BMBF) under the German-Indonesian anti-infective cooperation (GINAICO) project, a fellowship awarded by the German Academic Exchange Service (German: Deutscher Akademischer Austauschdienst or DAAD), and The President's Initiative and Networking Funds of the Helmholtz Association of German Research Centres (German: Helmholtz Gemeinschaft Deutscher Forschungszentren or HGF) under Contract Number VH-GS-202.

**Conflicts of Interest:** The authors declare no conflict of interest.
