Table 3.

Comparison of parameters of each cycle for γ-PGA production by B. siamensis IR10 in repeated fed-batch fermentation

Cycle number	1	2	3	4	5	6
Time (h)	24	24	24	20	20	20
Biomass (g/L)	14.88 ± 0.49	15.88 ± 0.52	16.73 ± 0.55	16.77 ± 0.56	17.08 ± 0.57	17.09 ± 0.56
γ-PGA concentration (g/L)	40.06 ± 1.33	44.77 ± 1.39	45.42 ± 1.41	44.10 ± 1.23	44.90 ± 1.26	44.98 ± 1.26
γ-PGA productivity (g/L/h)	1.67 ± 0.05	1.70 ± 0.06	1.71 ± 0.06	1.98 ± 0.06	2.02 ± 0.06	2.02 ± 0.06

The productivity was calculated according to the produced γ-PGA production as follows

Cycle 1: 40.06 ÷ 24 = 1.67; Cycle 2: (44.77 − 4.00) ÷ 24 = 1.70; Cycle 3: (45.42 − 4.40) ÷ 24 = 1.71; Cycle 4: (44.10 − 4.54) ÷ 20 = 1.98

Cycle 5: (44.90 − 4.53) ÷ 20 = 2.02; Cycle 6: (44.98 − 4.53) ÷ 20 = 2.02