Sulfate-reducing bacteria as new microorganisms for biological hydrogen production

• SRB have a very high content of hydrogenases and produce H2 fermentatively.
• We investigated the potential of SRB for H2 production using Desulfovibrio vulgaris.
• Formate was the best substrate for H2 production by D. vulgaris.
• In an ASTR D. vulgaris showed a high specific H2 production rate from formate.
• SRB could be explored for second stage systems or biocatalysts for formate to H2.

Sulfate-reducing bacteria (SRB) have an extremely high hydrogenase activity and in natural habitats where sulfate is limited, produce hydrogen fermentatively. However, the production of hydrogen by these microorganisms has been poorly explored. In this study we investigated the potential of SRB for H2 production using the model organism Desulfovibrio vulgaris Hildenborough. Among the three substrates tested (lactate, formate and ethanol), the highest H2 production was observed from formate, with 320 mL L−1medium of H2 being produced, while 21 and 5 mL L−1medium were produced from lactate and ethanol, respectively. By optimizing reaction conditions such as initial pH, metal cofactors, substrate concentration and cell load, a production of 560 mL L−1medium of H2 was obtained in an anaerobic stirred tank reactor (ASTR). In addition, a high specific hydrogen production rate (4.2 L g−1dcw d−1; 7 mmol g−1dcw h−1) and 100% efficiency of substrate conversion were achieved. These results demonstrate for the first time the potential of sulfate reducing bacteria for H2 production from formate.