Closing the 1,3-propanediol route enhances hydrogen production from glycerol by Halanaerobium saccharolyticum subsp. saccharolyticum

The effect of vitamin B₁₂ on hydrogen (H₂) and 1,3-propanediol (1,3-PD) production in glycerol fermentation of Halanaerobium saccharolyticum subsp. saccharolyticum was studied in batch cultivations. In addition, the effect of vitamin B₁₂ on glucose fermentation of H. saccharolyticum subsp. saccharolyticum and on glycerol fermentation of H. saccharolyticum subsp. senegalensis, that is a non-1,3-PD producing bacterium, and of Clostridium butyricum, that is known for vitamin B₁₂-independent 1,3-PD production, were studied for comparison. 1,3-PD production of H. saccharolyticum subsp. saccharolyticum was observed to be vitamin B₁₂-dependent and the H₂ production in glycerol fermentation was remarkably enhanced when 1,3-PD production was blocked by the lack of vitamin B₁₂ supplementation. The highest H₂ yield obtained by H. saccharolyticum subsp. saccharolyticum was 2.16 mol/mol glycerol. No significant effects of vitamin B₁₂ on metabolite production in glucose fermentation of H. saccharolyticum subsp. saccharolyticum or in glycerol fermentation of H. saccharolyticum subsp. senegalensis or C. butyricum were observed.