Unique hydrogen-making marine bacteria discovered

April 04, 2025

A new genomic study has uncovered previously unknown gene clusters in hydrogen-producing bacteria. This discovery could have significant implications for clean energy production.

Vibrionaceae, a well-known family of marine bacteria, are primarily recognized for their bioluminescence. However, they are also infamous for including the cholera-causing pathogen. Despite their widespread presence in ocean ecosystems, these bacteria have not been considered useful for biofuel production.

Now, researchers have found that some members of this bacterial family have a unique ability to generate large amounts of hydrogen gas. They achieve this by breaking down a compound called formate through fermentation, producing hydrogen and carbon dioxide in the process. This unexpected trait could offer a new path for developing energy solutions.

Unlocking the genetic mechanism behind hydrogen production

An international research 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 the Federal University of Rio de Janeiro, conducted a genomic analysis to understand the genetic basis of this phenomenon. Their study focused on sequencing all 16 known species of Vibrionaceae.

The researchers paid particular attention to the structure and function of the Hyf-type formate hydrogenlyase (FHL) gene cluster. This enzyme complex plays a crucial role in breaking down formate into hydrogen and carbon dioxide. A similar enzyme exists in Escherichia coli, but it produces significantly lower amounts of hydrogen compared to Vibrionaceae.

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

The study identified two previously unknown types of FHL gene clusters, bringing the total number in Vibrionaceae to six. This diversity likely emerged due to the bacteria adapting to different ecological environments over time.

Variability in production among species

The researchers also analyzed variations in hydrogen fermentation across different species. They found that Vibrio tritonius, a marine bacterium, and Vibrio porteresiae, a species living in mangrove-dwelling wild rice, showed the highest levels of hydrogen production. In contrast, Vibrio aerogenes and Vibrio mangrovi produced the least hydrogen.

The study further revealed that hydrogen production was linked to how efficiently the bacteria absorbed formate. Those with better formate uptake capabilities were able to generate more hydrogen.

“These genotypes strengthen formate metabolism as a possible key factor in maintaining fermentative hydrogen production in specific groups of vibrios,” Sawabe explained.

The researchers propose that certain species evolved higher hydrogen production as a mechanism to detoxify formate from their environment, a concept they call the formate detoxification hypothesis.

Their findings could also provide insights into hydrogen fermentation in other bacteria, including E. coli. This research not only enhances our understanding of microbial evolution but also offers new avenues for harnessing bacterial hydrogen production for sustainable energy applications.