The complex of macrotetrolide pesticides produced by Streptomyces griseus 34/249 under standard growth conditions consisted of nonactin, monactin, dinactin and trinactin in the ratio of 8:27:57:8 (by wt). After supplementing with sodium propionate (500 mg/60 mL of medium) at the beginning of cultivation, a mixture of nonactin, monactin, dinactin, trinactin and tetranactin (3:9:32:56:traces) was formed. Supplementing with sodium propionate and K2HPO4 (500 and 46 mg, respectively, per 60 mL of medium) resulted in the production of dinactin, trinactin and tetranactin (2:26:72). The addition of sodium acetate or sodium succinate was ineffective in this respect.