Table 1.

Factors and levels of single factor design

Factor	Level
Medium types	LBBMG, LB, TB, SOB, MX, LBBM, TB-GN, LBBSMG and LBBNM
Lactose concentration (g/L)	0, 2, 4, 6, 8, 10 and 12
Incubation size (%, v/v)	0.1, 0.2, 0.4, 0.8, 1.6 and 3.2
Initial pH	4.0, 5.0, 5.5, 6.0, 7.0, 8.0 and 9.0
Post-induction temperature (°C)	16, 20, 24, 28 and 32
Shaker rotational speed (rpm)	80, 120, 160, 200 and 240
Pre-induction period (h)	2, 4, 5, 6, 8 and 10
Medium volume (mL/250 mL)	12.5, 25, 50, 75, 100 and 125
Post-induction period (h)	4, 8, 12, 16, 20, 24 and 28