Rare genera of actinomycetes as potential producers of new antibiotics.

A literature survey covering more than twenty-three thousand bioactive microbial products including eight thousand antiinfectives demonstrated the increasing relevance of the so called 'rare' actinomycetes as a source of new antibiotics. Past and present efforts in the isolation of rare actinomycetes have enriched the Biosearch Italia Strain Collection with more than twenty thousand strains, showing that, when selective isolation methods are developed and extensively applied, some genera, such as Actinomadura, Actinoplanes, Micromonospora, Microtetraspora, are not rare at all and can be recovered from many soil samples. The current focus is on the isolation of members of Streptosporangiaceae family, given their promising chemical diversity.

Rare genera of actinomycetes as potential producers of new antibiotics.

A literature survey covering more than twenty-three thousand bioactive microbial products including eight thousand antiinfectives demonstrated the increasing relevance of the so called 'rare' actinomycetes as a source of new antibiotics. Past and present efforts in the isolation of rare actinomycetes have enriched the Biosearch Italia Strain Collection with more than twenty thousand strains, showing that, when selective isolation methods are developed and extensively applied, some genera, such as Actinomadura, Actinoplanes, Micromonospora, Microtetraspora, are not rare at all and can be recovered from many soil samples. The current focus is on the isolation of members of Streptosporangiaceae family, given their promising chemical diversity.

Antibiotic GE37468A: a new inhibitor of bacterial protein synthesis. III. Strain and fermentation study.

GE37468A is a new thiazolyl peptide antibiotic acting on Elongation Factor Tu, produced by fermentation of Streptomyces sp. ATCC 55365. The low (< 10 mg/liter) and poorly reproducible antibiotic productivity of the original soil isolate hampered the development of a scalable fermentation process. A tenfold increase of GE37468A productivity was achieved by selection of spontaneous morphochromatic variants, which appeared at high frequency in the wild type population. The higher producing ATCC 55365/O/5 colony was tyrosinase defective and blocked in the aerial mycelium differentiation (Amy-Mel- phenotype). The fermentation process of this stable and purified strain was rapidly optimized to achieve a further fourfold improvement in a fed-batch process.

Antibiotics A21459 A and B, new inhibitors of bacterial protein synthesis. I. Taxonomy, isolation and characterization.

Novel cyclic peptide antibiotics A21459 A and B are produced by a member of the genus Actinoplanes sp. These antibiotics inhibit bacterial protein synthesis and have selective antimicrobial activity against clostridia, mycoplasma and some Gram-negative bacteria.