Sugary droplets turn algal cells into miniature hydrogen factories

Hydrogen holds great potential as a clean energy source, largely because it produces no CO2 and only emits water vapor when used in a fuel cell. Most production, however, requires the use of fossil fuels, which has motivated much research into cleaner methods. A research team working in this area has made a discovery that could help these efforts along, demonstrating how algal cells can be turned into tiny hydrogen-producing factories by immersing them in sugary droplets.

Scientists are exploring all kinds of avenues in an effort to make hydrogen production greener. One pathway involves algae, which naturally produces the gas albeit in small amounts. Genetic modification, harnessing certain algal proteins or attempting to recreate this process artificially are approaches that have shown promise, and now scientists from the UK and China have uncovered another technique with plenty of potential.

The research team, made up of scientists from the University of Bristol and the Harbin Institute of Technology, began by looking at the way algal cells absorb carbon dioxide and produce oxygen through photosynthesis. It found that by trapping around 10,000 algal cells deep inside sugary droplets, the oxygen levels within them plummeted.

This had the effect of activating enzymes called hydrogenases, which in turn hijacked the process of photosynthesis and had the cells make hydrogen instead of oxygen. The team found it could supercharge this process by coating the droplets in a thin film of bacteria, which itself scavenged for oxygen and boosted activity of the hydrogenases.

“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,” says Professor Stephen Mann, from the University of Bristol.

These little creations measure just one-tenth of a millimeter in size, and the team says around a quarter of a million of these “microbial factories” could be squeezed into one milliliter of water. While it is very early days for the technology, the team believes there is plenty of potential to scale it up, or event adapt it for other purposes.

“Our methodology is facile and should be capable of scale-up without impairing the viability of the living cells,” says Professor Xin Huang from the Harbin Institute of Technology. “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.”

The research was published in the journal Nature Communications.

Source: University of Bristol

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