Physiology of a wild strain and high yielding mutants of Streptomyces rimosus, producing oxytetracycline.

A wild-type Streptomyces strain, yielding 1 g/L of oxytetracycline was compared with mutants giving up to 7 g/L, using complex media in stirred and shaken culture. Increased production of oxytetracycline was associated with high specific production rates and a longer production period. The superiority of the mutants was associated with changes in morphological behaviour during growth in submerged culture, and in their patterns of growth and respiration, coupled with increased resistance to the product. The productivity of the mutants was sensitive to the rate of stirring, the type of calcium carbonate used in the medium and the type of inoculum. Careful control of these factors was necessary to obtain high yields of oxytetracycline. With the exception of acetyl-CoA carboxylase, the levels of enzymes measured and of amounts of adenylates in the mycelium did not appear to be related to the degree of antibiotic production.