摘要 |
<p>This invention relates to Streptomyces avermitilis lacking branched-chain amino acid transaminase activity, branched-chain 2-oxo acid biosynthetic activity and, optionally and preferably, avermectin B-O-methyl transferase activity, methods for preparation thereof, and use thereof to produce natural and non-natural avermectins from branched-chain fatty acid or branched-chain 2-oxo acid precursors. Such avermectins are useful as parasiticides.</p> |