Poly-γ-glutamic acid produced from Bacillus licheniformis CGMCC 2876 as a potential substitute for polyacrylamide in the sugarcane industry

As an environmentally friendly and industrially useful biopolymer, poly‐γ‐glutamic acid (γ‐PGA) from Bacillus licheniformis CGMCC 2876 was characterized by the high‐resolution mass spectrometry and 1H NMR. A flocculating activity of 11,474.47 U mL−1 obtained with γ‐PGA, and the effects of carbon sources, ions, and chemical properties (D‐/L‐composition and molecular weight) on the production and flocculating activity of γ‐PGA were discussed. Being a bioflocculant in the sugar refinery process, the color and turbidity of the sugarcane juice was IU 1,877.36 and IU 341.41 with 0.8 ppm of γ‐PGA, respectively, which was as good as the most widely used chemically synthesized flocculant in the sugarcane industry—polyacrylamide with 1 ppm. The γ‐PGA produced from B. licheniformis CGMCC 2876 could be a promising alternate of chemically synthesized flocculants in the sugarcane industry. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1287–1294, 2015