Evaluation of the potential hydrogen production by diazotrophic Burkholderia species

•Two Burkholderia strains were used for hydrogen production.•The culture conditions of both Burkholderia strains were optimized for H2 production.•The hydrogen-production capacity of Burkholderia unamae and Burkholderia tropica was confirmed.

Hydrogen (H2) is considered one of the most promising fuels for sustainable energy. Because nitrogenase produces H2 as a normal by-product, we tested the N2-fixing bacterial strains Burkholderia unamae and Burkholderia tropica to determine their H2 production capacities. To maximize H2 production, several culture conditions were tested and optimized, including atmospheric conditions, carbon sources and chemical compounds such as enzyme cofactors and sugar cane molasses. The results showed that both strains were capable of H2 production. The culture medium with the highest H2 yield was composed of 1% v/v molasses enriched with Na2MoO4 (0.2 g/L), FeSO4 (0.2 g/L) and cysteine (0.02 g/L) under a partial vacuum (air 20% v/v) without Ar final atmosphere. Under these conditions, the highest H2 production rate obtained was 24.64 mmol H2/L for B. unamae. The present study contributes an optimization process for H2 production in N2-fixing Burkholderia species. We propose further research and development to improve H2 production rates in order to make biohydrogen a tangible reality.