A nocardioform actinomycete, SCC 1886, isolated from a soil sample collected in Ohio was found to produce, in fermentation, six novel macrocyclic lactones, the saccharocarcins. The producing culture was identified as Saccharothrix aerocolonigenes subsp. antibiotica based on the formation of fragmenting substrate mycelia, aerial mycelia that coalesce to form aerial colonies, whole-cell hydrolysates that contain meso-diaminopimelic acid, galactose and rhamnose and physiological comparisons to type species of the genus. Peak production of the saccharocarcins occurred after 95 hours of fermentation in a starch rich medium. The compounds were isolated from the fermentation broth by solvent extraction and purified by HPLC. Isolated compounds were active against Micrococcus luteus, Staphylococcus aureus and Chlamydia trachomatis; none were cytotoxic at concentrations up to 1.0 microgram/ml.