Enhanced Production of Acarbose and Concurrently Reduced Formation of Impurity C by Addition of Validamine in Fermentation of Actinoplanes utahensis ZJB-08196

Table 1

The kinetic parameters of acarbose fermentation with different fermentation methods.

Parameter	Cultivation method
	Control	A	B
Maximum acarbose titer (mg/L)	3560	4950	6606
Specific growth rate (1/h)	0.0086	0.0094	0.010
Acarbose productivity (mg/L/h)	21.19	29.46	39.32
Specific maltose consumption rate (1/h)	0.0053	0.0061	0.0103
Specific glucose consumption rate (1/h)	0.0046	0.0048	0.0068
Impurity C concentration (mg/L)	289	107	212
Impurity C productivity (mg/L/h)^a	1.49	0.64	1.26
Acarbose/impurity C^a	12.32	46.26	31.16

aThe value was calculated when acarbose reached its highest titer in the fermentation.
Method A: validamine was added at a final concentration of 20 mg/L in the fermentation medium prior to inoculation in batch culture.
Method B: validamine was added at a final concentration of 20 mg/L in the fermentation medium prior to inoculation in fed-batch culture. Twice feedings of a mixture of 6 g/L glucose, 14 g/L maltose, and 9 g/L soybean flour were performed at 72 h and 96 h.