Tokyo, Japan – A genomic study of hydrogen-producing bacteria has revealed entirely new gene clusters capable of producing large volumes of hydrogen.

Vibrionaceae, a family of marine bacteria, are known for their bioluminescence and for including the cholera pathogen. They have not been key players in biofuel production until now. Their ability to generate hydrogen gas by breaking down formate into carbon dioxide and hydrogen through fermentation has emerged as a green energy solution.

A team including Professor Tomoo Sawabe from Hokkaido University, Ramesh Kumar Natarajan from India’s National Institute for Interdisciplinary Science and Technology, and Fabiano Thompson from Brazil’s Federal University of Rio de Janeiro used genome sequencing to study this process. Their findings appeared in Current Microbiology.

The researchers analyzed all 16 known Vibrionaceae species, often found living with deep-sea animals. They studied the Hyf-type formate hydrogenlyase (FHL) gene cluster, which helps break down formate into hydrogen and carbon dioxide. This enzyme complex also exists in Escherichia coli, but Vibrionaceae produce much more hydrogen.

“These analyses reveal unexpected diversity of FHL gene clusters and relationships between gene clusters and function in hydrogen production ability,” Sawabe said.

The team identified two new FHL gene clusters, raising the total to six in Vibrionaceae. They believe this variety reflects how the bacteria evolved to fit different ecological niches.

The study showed that Vibrio tritonius and Vibrio porteresiae produced the most hydrogen, while Vibrio aerogenes and Vibrio mangrovi produced the least. Hydrogen production levels tied closely to how well the bacteria reabsorbed formate.

Sawabe noted that these traits suggest formate metabolism is key to hydrogen production in some Vibrionaceae species. The findings back the idea that some evolved higher hydrogen output to detoxify formate from their surroundings.

This research could also clarify hydrogen fermentation in bacteria like E. coli, opening doors to new green energy options.

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