Although high concentration KCl (>67.1 mM) suppressed cell growth, the maximum biomass with 201.2 mM had been brought forward to 16 h and had a
marked effect in prolonging cell viability. Metabolic flux and key enzyme activities analysis indicated that
enhanced GDH, GOGAT and GLR are important for γ -PGA production. Specifically, the expression of pgsB
was improved 9.6-fold by KCl added, which might be another reason for enhanced γ -PGA production.
In addition, that modulation of the D/L-glutamate ratio in γ -PGA and molecular weight could also be
accomplished by variation of KCl concentrations. This work provided a simple control strategy for γ -PGA
production, and it will be applied to γ -PGA production on a large scale in the future.