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Table 2 pH-controlled batch fermentations of C. celer on 10 g/l of glucose at pH 7 and 6, with and without N 2 sparging

From: Assessment of metabolic flux distribution in the thermophilic hydrogen producer Caloramator celer as affected by external pH and hydrogen partial pressure

  pH 7 pH 6
N2sparging ( Case I) No sparging ( Case II) N2sparging ( Case III) No sparging ( Case IV)
P H2max (kPa) 8 69 6 74
μ max (h-1) 1.09 ± 0.09 1.09 ± 0.08 0.43 ± 0.03 0.38 ± 0.05
Biomass concentration (g/l) 0.99 ± 0.03 1.13 ± 0.01 1.02 ± 0.03 1.01 ± 0.01
YX/ATP (gCDW/mol ATP) 11.5 ± 0.3 9.3 ± 0.1 6.3 ± 0.4 7.9 ± 0.2
YATP/S (mol ATP/mol glucose) 3.24 ± 0.03 3.18 ± 0.02 3.4 ± 0.08 3.48 ± 0.17
Q H2 (mmol H2/l/h) 27.1 ± 1.5 33.0 ± 0.1 19.9 ± 0.8 20.6 ± 0.5
Product yield (mol/mol glucose)     
   YX a 0.71 ± 0.01 0.75 ± 0.03 0.72 ± 0.01 0.75 ± 0.01
   YH2 a 2.32 ± 0.13 2.06 ± 0.13 3.10 ± 0.06 2.60 ± 0.03
   YA a 1.24 ± 0.01 1.28 ± 0.01 1.47 ± 0.07 1.35 ± 0.02
   YF a 0.37 ± 0.02 0.71 ± 0.12 0.14 ± 0.07 0.33 ± 0.06
   YE a 0.27 ± 0.01 0.37 ± 0.01 0.10 ± 0.01 0.39 ± 0.03
RVEP b 2.87 ± 0.11 2.8 ± 0.12 3.31 ± 0.08 3.39 ± 0.03
HAc/EtOH 4.5 ± 0.2 3.5 ± 0.1 14.2 ± 1.0 3.4 ± 0.3
Carbon recovery (%) 92.6 ± 0.6 94.0 ± 0.7 94.8 ± 4.2 100.3 ± 1.9
Redox recovery (%) 90.0 ± 0.6 97.5 ± 0.6 93.2 ± 4.1 102.3 ± 2.2
  1. aY indicates the yield of product (where x=biomass, H2=hydrogen, A=acetate, F=formate and E=ethanol) per mole of glucose consumed.
  2. bTotal molar reduction values of reduced end-products (RVEP = YH2 + 2 * YE) [19].