On the Microbiological Activity of a Plasma-peptide Fraction.

Abstract
A peptide fraction from calf''s plasma affects growth of Streptococcus faecalis R (8043), S. lactis (9790), and several Lactobacillus strains in a manner differing somewhat from Woolley''s strepogenin effect. While vit. B12 is apparently absent from the peptide fraction, the fraction appears to act synergistically with vit. B12- The peptide fraction does not replace amino acids, so that the effect is related to unhydrolyzed or partly hydrolyzed molecules. The peptide fraction contains considerable amts. of basic amino acids and little glutamic acid.