By overexpressing the positive regulatory gene, the silent gene cluster tjh in Streptomyces aureus SP-371 was successfully activated. The mutant strain could produce compounds with two distinct core strucutures which are pentacyclic and tetracyclic structures. It was speculated that these two types of skeletons might be derived from the same intermediate through two different post-modified pathways. These two tailoring pathways were intercepted by the double gene knockout, and aureuspiro was successfully accumulated in the mutant. Aureuspiro is a new natural product with a novel spiro-naphthoquinone structure. Despite aureuspiro is not a true intermediate in the biosynthesis of final products, it could support the hypothesis about structure of the common intermediate.

Key words: genome mining, biosynthesis, type II polyketides natural product, spiro ring