Phthoxazolin, a specific inhibitor of cellulose biosynthesis, produced by a strain of Streptomyces sp.

involved in humanand animal cells, it provides a promising target site for safe and non-selective herbicides of a novel class. Inhibitors of cellulose biosynthesis of microbial origin have not been documented, although a recent article3) from our laboratories suggested phthoramycin as a nonspecific inhibitor of polysaccharide biogenesis, probably acting on cellulose synthesis as well. We described here the discovery of a specific inhibitor of cellulose biosynthesis produced by Streptomyces sp. OM-5714.