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Table 1 Experimental growth parameters, PHB cell content, product yields and productivities by using different stirring speed

From: Enhancement of biohydrogen production rate in Rhodospirillum rubrum by a dynamic CO-feeding strategy using dark fermentation

Variable Stirring speed (rpm)
250 400 600 1000
µmax (h−1) 0.057 ± 0.005 0.056 ± 0.006 0.055 ± 0.005 0.057 ± 0.007
CX (g l−1) 1.46 ± 0.08 1.51 ± 0.06 1.57 ± 0.15 1.65 ± 0.11
PHB (% w w−1) 30.4 ± 2.4 25.7 ± 1.7 18.5 ± 1.6 17.1 ± 1.5
Batch time (h) 140 ± 5 134 ± 6 101 ± 4 94 ± 3
YX/CO (g g−1) 0.021 ± 0.004 0.022 ± 0.005 0.019 ± 0.002 0.023 ± 0.007
YX/AC (g g−1) 1.57 ± 0.33 1.48 ± 0.21 1.29 ± 0.26 1.03 ± 0.19
YPHB/CO (g g−1) 0.008 ± 0.0011 0.007 ± 0.0023 0.003 ± 0.0007 0.001 ± 0.0004
YPHB/AC (g g−1) 0.84 ± 0.08 0.78 ± 0.05 0.18 ± 0.01 0.13 ± 0.02
\(Y_{{{\text{H}}_{2} /{\text{CO}}}}\) (g g−1) 0.071 ± 0.006 0.069 ± 0.005 0.07 ± 0.008 0.067 ± 0.007
\(Y_{{{\text{CO}}_{2} /{\text{CO}}}}\) (g g−1) 1.01 ± 0.11 0.99 ± 0.14 1.03 ± 0.16 1.02 ± 0.24
PPHB × 103 (g l−1 h−1) 3.68 ± 0.18 3.09 ± 0.15 2.31 ± 0.14 1.08 ± 0.10
\(P_{{{\text{H}}_{2} }}\) (g l−1 h−1) 0.038 ± 0.005 0.036 ± 0.004 0.031 ± 0.006 0.033 ± 0.008