Models for Genetic Manipulation of Actinomycetes

The actinomycetes comprise a large diverse group of mycelial bacteria of both economic and medical importance. More than three thousand antibiotics, including most of those of clinical utility, are produced by this group of organisms. While thirty-four genera of actinomycetes are known to elaborate antimicrobial substances, the majority of antibiotics are produced by the genera Micromonospora, Nocardia, Streptoverticillium, Streptosporangium, and Streptomyces. Over 60% of known antibiotices are produced by the latter genus (3) in which more than 900 antibiotic-producing species have been described. Until recently, genetic exchange has been difficult to demonstrate in the actinomycetes. There has thus been little practical application of directed genetic recombination in this group. With the development of methodologies and techniques for DNA cloning in actinomycetes however, our ability to genetically manipulate these industrially important microorganisms should increase dramatically.