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Table 2 Hydrogen production rate (mmol/h), specific production rate (mmol/h/OD600), yield (H2 mmol/CO mmol) and growth rates for the individual and combined parameters

From: Effects of different operating parameters on hydrogen production by Parageobacillus thermoglucosidasius DSM 6285

Parameter

Production rate

Specific production rate

Yielda (H2 mmol/CO mmol)

Aerobic growth phase

Maximum (mmol/h)

Time (h)

Maximum (mmol/h * OD600)

Time (h)

∆OD600 (t12 − t0)

µ (1/h)

Control: 60 °C; pH 7.0; 0.04 mM Fe2+; no Ni2+; 50% CO; 12 h pre-culture; 2% inoculum

0.094 ± 0.016

35–48

0.163 ± 0.054

35–48

0.763 ± 0.026

0.467 ± 0.073

0.14

50 °C

0.055 ± 0.027

73–82

0.144 ± 0.06

73–82

0.698 ± 0.068

0.647 ± 0.044

0.163

55 °C

0.098 ± 0.006

34–48

0.124 ± 0.001

34–48

0.783 ± 0.014

0.716 ± 0.059

0.172

pH 5.5

0.06 ± 0.025

72–82

0.358 ± 0.103

72–82

0.606 ± 0.168

0.127 ± 0.035

0.128

pH 8.5

0.122 ± 0.005

59–72

0.294 ± 0.028

59–72

0.786 ± 0.018

0.348 ± 0.006

0.127

0.3 mM NiSO4·6H2O + 0.04 mM FeSO4·7H2O

0.078 ± 0.015

48–58

0.192 ± 0.035

48–58

0.716 ± 0.032

0.36 ± 0.056

0.122

0.08 mM FeSO4·7H2O

0.115 ± 0.020

25–35

0.24 ± 0.052

25–35

0.782 ± 0.012

0.442 ± 0.052

0.127

36:64 CO:air

0.073 ± 0.006

34–48

0.104 ± 0.016

34–48

0.748 ± 0.006

0.256 ± 0.042

0.095

75:25 CO:air

0.138 ± 0.009

34–48

0.351 ± 0.038

34–48

0.807 ± 0.022

0.136 ± 0.083

0.064

4 h pre-culture

0.129 ± 0.018

35–49

0.303 ± 0.046

35–49

0.796 ± 0.029

0.491 ± 0.015

0.372

24 h pre-culture

0.115 ± 0.025

34–48

0.27 ± 0.098

34–48

0.779 ± 0.013

0.316 ± 0.027

0.132

10% inoculum

0.101 ± 0.022

25–35

0.137 ± 0.025

25–35

0.806 ± 0.025

0.425 ± 0.063

0.052

20% inoculum

0.068 ± 0.023

59–73

0.108 ± 0.029

59–73

0.741 ± 0.028

0.151 ± 0.131

0.013

Combined: 55 °C, pH 7.0, 0.08 mM Fe2+, no Ni2+, 75% CO; 4 h pre-culture; 10% inoculum

0.182 ± 0.009

34–58

0.566 ± 0.024

34–58

0.808 ± 0.01

0.323 ± 0.02

0.32

  1. aCalculated between 24 h and 72 h cultivation time