Interspecific protoplast fusion in Streptomyces--selection of thermotolerant antibiotic-producing recombinant.

The thermotolerant fusants were obtained after interspecific protoplast fusion between S. qingfengmyceticus M15S (SMr, stop growth at 39 degrees C, producing qingfingmycin with wide antimicrobial spectrum) and S. hygroscopicus var. jinggangensis *75 (SMs, grow well at 42 degrees C, producing jingganmycin of antifungus) by directly selecting from the regeneration plates containing SM 100 micrograms/ml and incubated at 42 degrees C. The fusion frequency was about 10(-5) -10(-4). The stable thermotolerant recombinants with antimicrobial activity were obtained. The properties of their products were quite different from that of the parents (Qm, Jm). The antimicrobial substance produced by recombinant F6-6 consists of two components: one has acid-alkaline indicator property; the other is fluorescent under UV light. The antimicrobial products of F1-16, F1-38 and FM3-32 have absorption peaks at 274nm, which suggests that a cytosine moiety may be present in their molecules.