THE INDUCTION OF ANTIBIOTIC-SYNTHESIS IN SACCHAROPOLYSPORA-ERYTHRAEA AND STREPTOMYCES-HYGROSCOPICUS BY GROWTH-RATE DECREASE IS ACCOMPANIED BY A DOWN-REGULATION OF PROTEIN-SYNTHESIS RATE

The relationship between antibiotic production and culture growth rate in Saccharopolyspora erythraea and Streptomyces hygroscopicus was man ipulated by changing the growth-limiting substrate. Carbon- and nitrog en-limited cultures were studied and antibiotic synthesis was obtained in both cases in Saccharopolyspora erythraea cultures and in nitrogen -limited Streptomyces hygroscopicus cultures. In all cultures where an tibiotic was detected, onset of antibiotic production coincided with t he minimal protein synthesis rate. Further investigation in Saccharopo lyspora erythraea cultures indicated that this corresponded to minimum ratio of charged to uncharged tRNA, i.e. when uncharged tRNA accumula ted. This latter phenomenon was investigated in the presence of a prot ein synthesis inhibitor.