Detection of γ-Polyglutamic Acid (γ-PGA) by SDS-Page

γ-Polyglutamic acid (γ-PGA) produced by Bacillus suhtilis (natto) was detected by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and basic dye staining. Using this method, the molecular weight of γ-PGA was estimated at 275,000. This value was almost the same in all bacterial strains tested. As other applications of this SDS-PAGE method, degradation of γ-PGA by acid and heat treatment and a cross-linking reaction with carbodiimide and ethylenediamine were made visible in acrylamide gel. In the growth curve of the bacteria, γ-PGA production was detected in early stationary phase by SDS-PAGE.