Effective production of dehydro cyclic dipeptide albonoursin exhibiting pronuclear fusion inhibitory activity I. Taxonomy and fermentation

Strain KO-23, an actinomycete producing albonoursin as well as streptopyron e, was identified as Streptomyces albulus by morphological and biochemical studies. Fermentation conditions for albonoursin, a dehydro cyclic dipeptid e exhibiting a pronounced inhibitory activity toward pronuclear fusion of s ea urchin eggs, were optimized. Under the optimum conditions, the actinomyc ete produced 16 mg/liter of albonoursin, 30 times higher than that in the o riginal culture. The cells cultivated under these conditions highly express biosynthetic enzymes for albonoursin, and thus are available for biosynthe tic studies of dehydro cyclic peptides.