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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

ParameterProduction rateSpecific production rateYielda (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% inoculum0.094 ± 0.01635–480.163 ± 0.05435–480.763 ± 0.0260.467 ± 0.0730.14
50 °C0.055 ± 0.02773–820.144 ± 0.0673–820.698 ± 0.0680.647 ± 0.0440.163
55 °C0.098 ± 0.00634–480.124 ± 0.00134–480.783 ± 0.0140.716 ± 0.0590.172
pH 5.50.06 ± 0.02572–820.358 ± 0.10372–820.606 ± 0.1680.127 ± 0.0350.128
pH 8.50.122 ± 0.00559–720.294 ± 0.02859–720.786 ± 0.0180.348 ± 0.0060.127
0.3 mM NiSO4·6H2O + 0.04 mM FeSO4·7H2O0.078 ± 0.01548–580.192 ± 0.03548–580.716 ± 0.0320.36 ± 0.0560.122
0.08 mM FeSO4·7H2O0.115 ± 0.02025–350.24 ± 0.05225–350.782 ± 0.0120.442 ± 0.0520.127
36:64 CO:air0.073 ± 0.00634–480.104 ± 0.01634–480.748 ± 0.0060.256 ± 0.0420.095
75:25 CO:air0.138 ± 0.00934–480.351 ± 0.03834–480.807 ± 0.0220.136 ± 0.0830.064
4 h pre-culture0.129 ± 0.01835–490.303 ± 0.04635–490.796 ± 0.0290.491 ± 0.0150.372
24 h pre-culture0.115 ± 0.02534–480.27 ± 0.09834–480.779 ± 0.0130.316 ± 0.0270.132
10% inoculum0.101 ± 0.02225–350.137 ± 0.02525–350.806 ± 0.0250.425 ± 0.0630.052
20% inoculum0.068 ± 0.02359–730.108 ± 0.02959–730.741 ± 0.0280.151 ± 0.1310.013
Combined: 55 °C, pH 7.0, 0.08 mM Fe2+, no Ni2+, 75% CO; 4 h pre-culture; 10% inoculum0.182 ± 0.00934–580.566 ± 0.02434–580.808 ± 0.010.323 ± 0.020.32
  1. aCalculated between 24 h and 72 h cultivation time