New milbemycins from Streptomyces hygroscopicus subsp. aureolacrimosus: fermantation, isolation and strucutre elucidation.

Twelve new milbemycins have been isolated and characterized from some strains derived from Streptomyces hygroscopicus subsp. aureolacrimosus SANK 60286 and SANK 60526. The metabolites 1 approximately 4 and 9 approximately 11 were produced by strain RM28D-688 SANK 60797 as minor products.

Bioconversion of milbemycin-related compounds: isolation and utilization of non-producer, strain RNBC-5-51.

A non-producing strain, the so-called strain RNBC-5-51 SANK 60198, was isolated during a screening program of strain improvement in the milbemycin production. Strain RNBC-5-51 indicated almost the same characteristics as those in the parent strain, that is, the abundant spore formation on agar media and the good growth in liquid media. But it does not produce any kind of milbemycins.

Bioconversion of milbemycin-related compounds: biosynthetic pathway of milbemycins.

Streptomyces hygroscopicus subsp. aureolacrimosus SANK 60286 and SANK 60576 produce many kinds of milbemycins. Among them, milbemycin alpha11, alpha14, A3, and A4 have the most effective acaricidal activity.