Scientists have created microbial “factories” for hydrogen

Hydrogen is considered one of the alternative fuels capable of powering a wide range of machines and technologies in the future.

Although the combustion of hydrogen itself produces no emissions, its production is energy-intensive and most of its current production depends on fossil fuels. Some microorganisms may be a much purer source of hydrogen.

A British-Chinese team of scientists from the University of Bristol and the Harbin Institute of Technology (Charbine Institute of Technology) has managed to produce miniature bioreactors filled with algal cells that produce hydrogen instead of oxygen.

The research results were published in the scientific journal Nature Communications.

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Algal cells normally bind carbon dioxide by releasing oxygen during the photosynthesis process. However, the algae themselves need oxygen for normal functioning.

If they are denied access to oxygen, the hydrogenase enzyme is activated in their cells, which causes them to start producing molecular hydrogen (H₂).

The authors of the new study used this principle. Nearly 10,000 chlorella algae cells were “forced” into a drop of sugar with dextran (a type of polysaccharide) with a diameter of several tens of micrometers.

The droplets were then hyperosmotically compressed, so that the “trapped” cells formed a compact spherical structure. Since the cells inside the “sphere” had limited access to oxygen, the dehydrogenase was activated and the cells started producing hydrogen.

To increase the production of molecular hydrogen, the droplets were coated with a thin film of bacteria that consumed even more oxygen. This activated the hydrogenase in more algal cells.

Small organisms with great potential

In one milliliter of water it is possible to prepare about a quarter of a million such microscopic bioreactors. The technology is still in the early stages of development, but the authors promise great things from it.

“The use of simple droplets as vectors to control cell organization and photosynthesis in artificial microspaces offers a potentially ecological approach to hydrogen production, which we want to develop further in future work,” advises one of the authors Stephen Mann.

Droplet “factories” with algae and bacteria could therefore be a valuable and “green” source of hydrogen-based hydrogen for a wide range of applications.

Another study author, Xin Huang, adds that they can use this method to create other types of living microreactors that could produce different chemicals. For example, alcohol.

“Our method is accessible and should be able to increase without compromising the viability of living cells. It also appears flexible. For example, we have recently captured a large number of yeast cells and used microbial reactors to produce ethanol,” concludes Huang.