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A new antibacterial antibiotic, designated simaomicin a (LL-D42067a) was isolated from the fermentation broth of an actinomycete strain. Based on cultural, physiological, morphological and chemical characteristics, culture LL-D42067was identified as a newsubspecies of Actinomadura madurae. Simaomicin a demonstrated potent activity against Gram-positive bacteria and was active in vivo against a variety of Eimeria species causing coccidiosis in chickens.

Culture LL-F42248, preliminarily identified as an unusual Streptomyces species, was found to produce the novel antibiotic 1, designated LL-F42248a. This compound, which is related to the coproduced pyrrolomycin C (2)i:) is the first tricyclic member of this family and is the only chiral pyrrolomycin reported to date.2) The culture was grown in a 30-liter tank fer

The nitro group of dioxapyrrolomycin (1) was shown to be introduced via direct biochemical nitration in cultures of the producing organism Streptomyces fumanus containing K'5N'803 as the sole source of nitrogen; the nitro group of dioxapyrrolomycin produced under these conditions contained the same ratio of 1 8 0 to 15N as was present in the labelled nitrate precursor, the extent of 1 8 0 enrichment of the nitro group being determined by negative electron impact mass spectrometry and 15N n.m.r. spectroscopy. 353