Abstract

Streptomyces antibioticus ETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual for Streptomyces spores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions.