Table 3 Comparison of different seed nitrogen sources

Soy peptone by flask

Spent yeast cell dry powder by shaking flask

Soy peptone by 5 L bioreactor

Spent yeast cell dry powder by 5 L bioreactor

Spent yeast cell dry powder by 50 L bioreactor

Fermentation period (h)

56

72

72

70

95

Glucose consumption (g/L)

117

87

112

113

107

Pyruvic acid production (g/L)

42.2

48.3

56.9

63.4

65.1

Yield of pyruvic acids on glucose (g/g)

0.36

0.55

0.53

0.59

0.61

Pyruvic acids productivity (g/L/h)

0.75

0.67

0.79

0.91

0.69