Scientists have developed droplet-based microbial factories that synthesize hydrogen when exposed to sunlight and air. The microbial factories could make hydrogen-based alternative fuels more economical.
Hydrogen has been promised as the remedy for the world's addiction to fossil fuels. But the fuel isn't cheap or easy to make -- at least not cheap enough to make it an economical substitute for traditional oil and gas fuels.
In addition to being relatively expensive, current methods for hydrogen production are energy intensive and yield unwanted byproducts.
Cleaner, more efficient hydrogen-producing technologies, however, could help make a hydrogen economy a reality.
For the new study, published Wednesday in the journal Nature Communications, researchers hijacked the synthesizing abilities of algae cells.
Typically, algae cells generate oxygen via photosynthesis, but when starved of oxygen, algae cells start producing hydrogenases, special enzymes that alter the photosynthetic pathway to generate hydrogen.
Scientists were able to limit the algae cells' access to oxygen by burying them deep inside sugary droplets. Using osmotic compression, researchers were able to pack more than 10,000 cells into each sugary droplet.
The researchers then coated the droplet in a film of oxygen-eating bacteria to boost the aerobic conditions and trigger the production of hydrogenases.
As result, the oxygen-starved algae cells started generating lots and lots of hydrogen.
"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," study co-author Stephen Mann said in a news release.
Mann is co-director of the Max Planck Bristol Center for Minimal Biology at the University of Bristol.
In followup studies, researchers plan to test their ability to scale production of the hydrogen-making droplets.
"Our methodology is facile and should be capable of scale-up without impairing the viability of the living cells," said study co-author Xin Huang.
"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," said Huang, a professor at the Harbin Institute of Technology in China.