Ultrafiltration associated with microporous resin decolorizing the Bacillus subtilis fermentation broth for the production of γ-polyglutamic acid

Abstract Currently, the industrial production of γ-polyglutamic acid (γ-PGA) was mainly based on microbial fermentation, but the decolorization technology still needs to be improved. Therefore, in this study, the optimal decolorization conditions and efficiencies were investigated. As the result, D4006 was an ideal resin for the decolorization of γ-PGA fermentation broth. The optimal decolorization pH value and temperature were pH 3 and 40 °C, respectively; ultrafiltration differential pressure, temperature and time were 0.2 MPa, 40 °C, and 6 h, respectively. Moreover, the combination of D4006 (3 %) resin on the basis of ultrafiltration had a better decolorization effect on γ-PGA fermentation broth, and the decolorization rate reached 96.8 %.