PRODUCTION OF GLUTAMYL POLYPEPTIDE BY BACILLUS SUBTILIS

Abstract

Static and shake cultures were used. Yields of 2 to 3 mg. of peptide/ml. occur on modified Sauton''s medium in static cultures. Highest yields of peptide result when the organism is grown in shaken flasks on the following medium: glycerol, 80 g.; citric acid, 12 g.; L-glutamic acid, 20 g.; NH4Cl, 7.0 g.; MgSO4, 0.5 g.; FeCl3 6H2O, 0.04 g.; K2HPO4, 0.5 g.; and tap water to 1000 ml., pH 7.4 with NaOH. Under these conditions, yields in excess of 15 mg./ml. are obtained in 3 to 4 days. The amt. of D-glutamic acid in peptide samples varies from approx. 20% to approx. 80% of the total. Peptide produced in static cultures usually contains a higher % of D-glutamic acid than prepns. from shaken cultures. Highly purified prepns. are obtained in good yield by precipitation with CuSO4 or ethanol. Peptide in the form of the free acid is insoluble in water, but the Na salt is very soluble. Culture filtrates contain an enzyme system capable of degrading the peptide. Free glutamic acid and compounds which are composed of glutamic acid and presumed to be peptides of molecular wt. lower than the original peptide are formed when the enzyme soln. is incubated with peptide.