Growth Factors for Bacteria

Abstract

Two additional unidentified factors are required by Lado-bacillus casei for growth in a medium containing amino acids and the known growth factors. Both factors are contained in a water extract of yeast and can be separated by adsorption on norite. The adsorbed factor has been considerably purified and certain of its properties ascertained. It is extractable by butyl alcohol (pH 4) but not by ether; is precipitated by base precipitants (e.g., phosphotungstic acid); is fairly stable to acids and alkali, but its activity is destroyed by acetic anhydride and H2O2.