The effects of constant temperature fermentation time on poly-γ-glutamic acid (γ-PGA) production by B. amyloliquefaciens YP-2 was investigated under different temperatures (31 °C, 33 °C, 35 °C, 37 °C and 39 °C). The scheme of step-wise temperature control (0 ~ 4 h, 35 °C ; 4 ~ 7 h, 31 °C ; 7 ~ 10 h, 33 °C ;10 ~ 26 h, 37 °C ;26 ~ 60 h, 31 °C) was formulated following the kinetic analysis of γ-PGA fermentation. Under the variable temperature fermentation condition, the maximum cell productivity and γ-PGA yield reached 1.66 g/(L ⋅ h) 1 and 29.50 g/L, respectively, which was 4.4% and 11.8% higher than those in optimal constant temperature at 37 °C. The results indicated the variable temperature fermentation effectively improved the γ-PGA production by B. amyloliquefaciens YP-2 comparing with constant temperature fermentation. [ABSTRACT FROM AUTHOR]