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.