Genetic Recombination and Transformation in Protoplasts of Thermomonospora fusca.

Protoplasts were produced from the thermophilic actinomycete Thermomonospora fusca and were regenerated to 0.1% of the direct count on regeneration agar. Recombination after protoplast fusion was demonstrated with drug-resistant mutants of T. fusca YX. A single thiostrepton-resistant colony was isolated after transformation of T. fusca YX with the streptomycete vector pIJ702, providing the first evidence for transformation in the genus Thermomonospora and suggesting that some mesophilic streptomycete genes can be expressed in thermophilic actinomycetes. Of 20 thermophilic actinomycete strains isolated from self-heated composts, 3 were found to harbor native plasmid DNA, providing potential sequences for the development of Thermomonospora-Streptomyces shuttle vectors.