Effect of C, N source and m_C/m_N on hydrogen-producing characteristic of fermentative H₂-producing strain RF-9

The influence of different carbon, nitrogen sources and carbon/nitrogen mass ratio on H₂-producing of strain RF-9 were studied in this work in batch test. The results showed that the composite of glucose, corn starch olquor and yeast extract paste were the optimal carbon and nitrogen sources of H₂-producing strain RF-9. The carbon-nitrogen mass ratio (m_C/m_N) has a significant influence on fermentative hydrogen production capacity of strain RF-9, cell growth and fermentative H₂-producing ability would be improved with increasing m_C/m_N value. When the value of m_C/m_N was 5.5, utilization ratio of glucose, release of H₂ and cell concentration reached maximal value which were 93.3%, 135.9 mmol/L and 0.723 g/L, respectively. Moreover, the total concentration of fermentative liquid end products obtained correspondingly maximal value of 5 850.8 mg/L, among which ethanol and acetic acid were main soluble metabolites, the pH of culture medium dropped to the minimum value of 3.36. When m_C/m_N exceeded 5.5, cell growth and metabolic characteristic of strain RF-9 were restrained and showed dropping tendency.