Yeast Extract Promotes Cell Growth and Induces Production of Polyvinyl Alcohol-Degrading Enzymes

Table 2

Effects of multiple yeast extract addition on cell growth and PVAases production in fermentor. Number (1) 2 g yeast extract per liter of culture broth added at 18 h with a volume of 96 mL; number (2) 1 g yeast extract per liter of culture broth added at 18 h and 20 h with a volume of 48 mL each time; number (3) 0.67 g yeast extract per liter of culture broth added at 18 h, 20 h, and 22 h with a volume of 32 mL each time; number (4) 0.50 g yeast extract per liter of culture broth added at 18 h, 20 h, 22 h, and 24 h with a volume of 24 mL each time.

No.	Addition time				Experimental results
	18 h	20 h	22 h	24 h	DCW (g/L)	PVAases activity (U/mL)	Specific PVAases activity (kU/g)
	Concentration of yeast extract (g/L)
0	0 (Control)				1.08 ± 0.07	1.23 ± 0.10	1.14 ± 0.10
1	2				1.52 ± 0.06	2.31 ± 0.08	1.52 ± 0.12
2	1	1			1.54 ± 0.05	2.66 ± 0.09	1.73 ± 0.07
3	0.67	0.67	0.67		1.56 ± 0.08	3.27 ± 0.11	2.09 ± 0.13
4	0.5	0.5	0.5	0.5	1.58 ± 0.07	3.41 ± 0.13	2.15 ± 0.09