Rare genera of actinomycetes as potential producers of new antibiotics

A literature survey covering more than twenty-three thousand bioactive micr obial products including eight thousand antiinfectives demonstrated the inc reasing relevance of the so called 'rare' actinomycetes as a source of new antibiotics. Past and present efforts in the isolation of rare actinomycete s have enriched the Biosearch Italia Strain Collection with more than twent y thousand strains, showing that, when selective isolation methods are deve loped and extensively applied, some genera, such as Actinomadura, Actinopla nes, Micromonospora, Microtetraspora, are not rare at all and can be recove red from many soil samples. The current focus is on the isolation of member s of Streptosporangiaceae family, given their promising chemical diversity.