Genetic complementation of Streptomyces tendae deficient in nikkomycin production

Streptomyces tendae Tü 901 produces the nucleoside peptide antibiotic nikkomycin. In shot-gun cloning experiments using pIJ699 as vector we isolated a 9.4-kb DNA fragment from S. tendae which complemented the nikkomycin nonproducing mutant NP9 to the formation of nikkomycin C/Cx and Kx. Nikkomycins were identified by HPLC analyses and their characteristic UV spectra. In Southern hybridization experiments the cloned DNA exclusively reacted with S. tendae DNA sequences. As shown by Northern dot blotting, transcripts of the isolated DNA fragment were only detected during stationary growth and correlated with the extent of nikkomycin production. When the recombinant plasmid pNP113 containing the 9.4-kb DNA fragment was transferred into the over-producing mutant Tü901/S2566, transformants exhibited a significantly decreased capacity for forming nikkomycin. Southern analysis of genomic DNA of these transformants revealed that severe rearrangements occurred in DNA sequences homologous to the 9.4-kb insert of pNP113.