was due to the change of γ -PGA conformation caused by KCl. Previous studies from He et al. showed that the γ -PGA was in a helical conformation at low ionic strength, while changed to a mixture
of helix and β-sheet at 0.1 M, and adopted predominantly β-sheet
at 0.5 M [20]. These results indicated that KCl can be used to control the viscosity of γ -PGA fermentation broth, thereby improving
γ -PGA production.