CO2 fraction % 0.03 3.32 ± 0.12 8.86 ± 0.24 13.84 ± 0.27
CO2 conc. mmol/L 0.001 ± 0.0006 1.16± 0.07 3.05 ± 0.09 4.81 ± 0.12
Pra ug/L/h 1521.9 2164.2 2279.1 750.0
SPRb ug/g(DCW)/h 45.2 ± 0.9 64.4 ± 2.1 69.4 ± 1.2 23.7 ± 1.6
SGCRc mmol/g(DCW)/h 0.18 0.17 0.14 0.10
?Yp/s ug/mmol 252.9 382.4 480.5 248.3
SCERd mmol/g(DCW)/h 1.03 0.90 0.73 0.54
CO2/Glucose C(mol)/C(mol) % 94.6 ± 2.1 89.2 ± 1.9 85.6 ± 1.5 93.3 ± 1.3
a, Pr: Vitamin B12 production rate
b, SPR: specific vitamin B12 production rate
c, SGCR: specific glucose consumption rate
d, SCER: specific carbon dioxide evolution rate
Table 2: Yield factors of vitamin B12 fermentation under various influent CO2 concentration for 48h with the cultivations of stationary phase biomass transfered from a well cultured 50L fermentor.