Six novel metabolites containing a lactone moiety as a common structural fe
ature, along with the previously described (-)-blastmycinolactol, have been
isolated from the cultivation broth of a bacterium of the genus Streptomyc
es isolated from marine sediment. On the basis of the results of combined s
pectroscopic analysis, the structures of the new compounds have been determ
ined as butenolides and 3-hydroxy-gamma -butyrolactones.