INFLUENCE OF NUTRIENT EXCESS ON INTRACELLULAR PROTEINS COMPOSITION INRELATION TO SPIRAMYCIN PRODUCTION, IN STREPTOMYCES-AMBOFACIENS

The protein profile on media favouring or reducing spiramycin biosynth esis in S. ambofaciens, was examined using SDS-polyacrylamide gradient gel electrophoresis over a time course of 144 h. Changes in the patte rn of protein synthesis were observed which varied according to the nu trient medium conditions and appeared to suggest the presence of prote in subsets specific to the production phase, which were probably invol ved in the switch to secondary metabolism and the onset of antibiotic synthesis. Excess of ammonium, glycerol or phosphate provoked the pers istence of a protein band during the whole culture period, which was d etected only during growth phase in the control producer culture. In a ddition, the nutrient excess caused the suppression of spiramycin prod uction and the absence of two protein bands which appeared only in pro duction phase in the control producer culture.