Green alga produces hydrogen under aerobic conditions

Strains of the microscopic alga Chlorella vulgaris discovered in a South Korean lake have brought us one step closer to a sustainable biofuel. In a study published in Nature Communications, an international team of researchers describe how these strains can produce hydrogen without the need for an oxygen-free environment.

Most of the world's demand for hydrogen is currently met by fossil fuels. Photosynthetic hydrogen production offers a promising alternative, but hydrogenases, the crucial enzymes which produce molecular hydrogen by electron transfer, are inactivated by oxygen. Biohydrogen production is therefore limited by its need for anaerobic conditions.

The research team, which included R.A.I. Abou-Shanab of the City of Scientific Research and Technology in Alexandria, Egypt, discovered two strains of C. vulgaris that can produce hydrogen via photosynthesis even under aerobic conditions thanks to an oxygen-tolerant hydrogenase. The team measured hydrogenase activity and the amount of hydrogen produced by the algae under various atmospheric conditions. Hydrogen production occurred even at oxygen concentrations similar to Earth's atmosphere, a promising advance in biohydrogen production research.

"This has a big impact on applications like biomimetic catalysis and biomimetic photovoltaics, along with direct photosynthetic biohydrogen production," says Byong-Hun Jeon of Yonsei University in South Korea, who led the study, although first "it will be necessary to fully characterize the oxygen-tolerating enzymes."

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