A New Method to Purify Poly-γ-glutamic Acid Using Gemini Quaternary Ammonium Salts and Characterization of its Ionic Complex

Poly-gamma-glutamic acid (γ-PGA) is a water-soluble, nontoxic biodegradable polymer. It is extensively utilized in medicines, foodstuffs, and cosmetics, as well as in water treatment. Highly pure γ-PGA is required for various purposes. In many cases, γ-PGA is produced by microbes of Bacillus sp. However, an increase in the viscosity of the culture broth is one of the major problems of γ-PGA production, as higher viscosity makes the separation...