IM2, a new inducer of blue pigment production in Streptomyces sp. MAFF 10-06015

A new autoregulator designated as IM2, which induces blue pigment production in Streptomyces sp. MAFF 10-06015, was discovered. The culture conditions developed here for the production of the pigment by the strain did not require the addition of an artificial inducer such as γ-nonalactone or the autoregulator of S. virginiae MAFF 10-06014, IM, which induces the production of virginiamycin by this microorganism. The major improvements in the culture conditions for spontaneous pigment production included the inoculation conditions and the dilution of the medium. The method of IM2 assay was established and the time courses of IM2 production were followed in the cultures using flasks and a jar fermentor. It was confirmed that IM2 released once into the culture filtrate from the cells was taken up into the cells again. The concentration of IM required to induce pigment production in Streptomyces sp. MAFF 10-06015 was 50 u·ml⁻¹. However a concentration of 200 u·ml⁻¹ of IM2 was unable to induce the production of virginiamycin in S. virginiae MAFF 10-06014.