Enhanced production of antibiotics by Pecilomyces lilacinus under alkaline conditions associated with morphological change.

The production of the group of peptide antibiotics called No. 1907 by Paecilomyces lilacinus was stabilized and enhanced by mono-spore isolation followed by strain improvement, and the production seemed to be related to a morphological change of the strain. Unstable and a low productivity (below 10 micrograms/ml) of the antibiotics No. 1907 by P. lilacinus was greatly improved up to 140 micrograms/ml by successive mono-spore isolation along with mutagenization. Alkaline conditions caused by adding Na2CO3, K2CO3, NaHCO3 or KHCO3 were essential to obtain high production of the antibiotics following simultaneous morphological change of the cells from filamentous mycelia to round arthroconidia. Resting cell experiments showed that a significant amount of antibiotics (213 micrograms/ml) was synthesized by the filamentous cells along with their morphological change to arthroconidia in the presence of glucose under the alkaline conditions.