Control of avermectin biosynthesis in Streptomyces avermitilis for the selective production of a useful component.

I. Biosynthesis of Avermectins A. Incorporation of Labeled Precursors B. Biosynthetically Blocked Mutants and Characteristics of Each Step in Avermectin Biosynthetic Pathway 1. aveA {aveAI and aveAIh step for polyketide synthase) 2. aveB (step for glycosylation) 3. aveC (step for C22~23-dehydration) 4. aveD (step for C5 O-methylation) 5. aveE (step for furan ring formation at C6 to C8a) 6. aveF (step for C5 keto reduction) 7. aveR (step for regulation of biosynthesis) 8. X (step concerning selective incorporation of branched-chain fatty acid into avermectin aglycones) C. Genetic Background of Avermectin Biosynthesis II. Application to the Selective Production of Useful Components(s) A. Production of Specific Component(s) 1. Selective Production of Avermectins Bla and B2a 2. Selective Production of 5-Oxoavermectins Bla and B2a 3. Selective Production of Avermectin B2a 4. Suppression of the Accumulation of Useless Toxic Compound, Oligomycin III. Conclusion