Tiny droplet-based microbial factories that produce hydrogen

Research creates hydrogen-producing living droplets, paving way for alternative future energy sources.


Hydrogen, as a climate-neutral fuel, offers several uses as a future energy source. But, the problem is making hydrogen uses lots of energy.

In collaboration with the Harbin Institute of Technology in China, a discovery by the University of Bristol could hold the key to developing new solutions.

Scientists have developed tiny-droplet-based microbial factories that produce hydrogen when exposed to daylight in the air.

Scientists trapped algal cells, which were then crammed together by osmotic compression. By burying the cells deep inside the droplets, oxygen levels fell to a level that switched on special enzymes called hydrogenases that hijacked the normal photosynthetic pathway to produce hydrogen.

In this way, around a quarter of a million microbial factories, typically only one-tenth of a millimeter in size, could be prepared in one milliliter of water.

To increase the level of hydrogen evolution, the team coated the living micro-reactors with a thin shell of bacteria, which could scavenge for oxygen and therefore increase the number of algal cells geared up for hydrogenase activity.

Although still early, the work provides a step towards photobiological green energy development under natural aerobic conditions.

Professor Stephen Mann, Co-Director of the Max Planck Bristol Centre for Minimal Biology at Bristol, said: “Using simple droplets as vectors for controlling algal cell organization and photosynthesis in synthetic micro-spaces offers a potentially environmentally benign approach to hydrogen production that we hope to develop in future work.”

Professor Xin Huang at Harbin Institute of Technology added“Our methodology is facile and should be capable of scale-up without impairing the viability of the living cells. It also seems flexible; for example, we recently captured large numbers of yeast cells in the droplets and used the microbial reactors for ethanol production.”

Journal Reference:
  1. Xu, Z., Wang, S., Zhao, C. et al. Photosynthetic hydrogen production by droplet-based microbial micro-reactors under aerobic conditions. Nat Commun 11, 5985 (2020). DOI: 10.1038/s41467-020-19823-5
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