Impact of formate on the growth and productivity of Clostridium ljungdahlii PETC and Clostridium carboxidivorans P7 grown on syngas

Autores/as

  • Sara Ramió-Pujol 1. LEQUIA, Institute of the Environment, University of Girona, Girona. 2. Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona.
  • Ramon Ganigué LEQUIA, Institute of the Environment, University of Girona, Girona.
  • Lluís Bañeras Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona.
  • Jesús Colprim LEQUIA, Institute of the Environment, University of Girona, Girona.

Palabras clave:

Clostridium carboxidivorans, Clostridium ljungdhalii, syngas fermentation, biofuels, formate

Resumen

The current energy model based on fossil fuels is coming to an end due to the increase in global energy demand. Biofuels such as ethanol and butanol can be produced through the syngas fermentation by acetogenic bacteria. The present work hypothesizes that formate addition would positively impact kinetic parameters for growth and alcohol production in Clostridium ljungdahlii PETC and Clostridium carboxidivorans P7 by diminishing the need for reducing equivalents. Fermentation experiments were conducted using completely anaerobic batch cultures at different pH values and formate concentrations. PETC cultures were more tolerant to formate concentrations than P7, specially at pH 5.0 and 6.0. Complete growth inhibition of PETC occurred at sodium formate concentrations of 30.0 mM; however, no differences in growth rates were observed at pH 7.0 for the two strains. Incubation at formate concentrations lower than 2.0 mM resulted in increased growth rates for both strains. The most recognizable effects of formate addition on the fermentation products were the increase in the total carbon fixed into acids and alcohols at pH 5.0 and pH 6.0, as well as, a higher ethanol to total products ratio at pH 7.0. Taken all together, these results show the ability of acetogens to use formate diminishing the energy demand for growth, and enhancing strain productivity. [Int Microbiol 2014; 17(4):195-204]

Keywords: Clostridium carboxidivorans · Clostridium ljungdhalii · syngas fermentation · biofuels · formate

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Número

Vol. 17 Núm. 4 (2014)

Sección

Research Articles

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