Researchers at the University of Edinburgh have demonstrated a microbial process that uses waste bread to generate hydrogen for industrial hydrogenation, potentially reducing reliance on fossil fuels across food, pharmaceutical and materials production.
The humble breadcrumb could help reduce fossil fuel use in one of the chemical industry’s most widely deployed reactions, according to new research from the University of Edinburgh.
Scientists at the university’s Wallace Lab have developed a one-pot microbial system that uses waste bread to generate hydrogen gas for hydrogenation – a reaction central to the manufacture of foods, pharmaceuticals, plastics, fuels and fine chemicals.
Hydrogenation is widely used in both food processing and industrial chemistry. In the food sector, it converts liquid vegetable oils into more stable solid fats. In industrial applications, it is a key step in synthesising pharmaceuticals, polymers and specialty chemicals, typically using metal catalysts such as nickel, palladium or platinum.
Currently, hydrogenation depends almost entirely on hydrogen gas produced from fossil fuels. Producing this hydrogen is energy-intensive and often requires high temperatures and pressures.
In the new study, published in Nature Chemistry, researchers showed that hydrogenation can instead be powered by hydrogen generated naturally by living bacteria.
Hydrogenation underpins huge parts of modern manufacturing, but it still relies almost entirely on hydrogen made from fossil fuels.
A common laboratory strain of E. coli was fed sugars extracted from waste bread and cultivated in oxygen-free conditions. Under these conditions, the bacteria produced hydrogen gas as part of their metabolism. When a small amount of palladium catalyst and a target chemical were added to the same sealed flask, the hydrogen generated by the microbes was sufficient to drive hydrogenation under near-room temperature conditions.
The entire process took place in a single sealed vessel, without the need for externally supplied hydrogen gas or fossil fuel inputs.
According to a life-cycle analysis conducted by the team, the system can be carbon-negative when waste bread is used as the feedstock. By avoiding fossil-derived hydrogen and diverting food waste from landfill or incineration, the process removes more greenhouse gases than it emits.
Professor Stephen Wallace, Personal Chair of Chemical Biotechnology at the University of Edinburgh’s School of Biological Sciences, said: “Hydrogenation underpins huge parts of modern manufacturing, but it still relies almost entirely on hydrogen made from fossil fuels. What we’ve shown is that living cells can supply that hydrogen directly, using waste as a feedstock, and do so in a way that can actually be carbon-negative.
“This approach isn’t limited to food chemistry either. Hydrogenation is used across pharmaceuticals, fine chemicals and materials. Being able to run these reactions using microbial hydrogen opens up new possibilities for sustainable manufacturing at scale.”
The research team plans to expand the system to a wider range of commercially relevant products and to investigate alternative microbial hosts that could potentially remove the need for metallic catalysts altogether.
The study was funded by UK Research and Innovation, the European Research Council, the Industrial Biotechnology Innovation Centre and the High-Value Biorenewables Network.
Dr Susan Bodie, Director of Innovation Development and Licensing at Edinburgh Innovations, said the work formed part of a broader programme using engineering biology to add value to waste materials.
“Professor Wallace is one of several researchers at the University of Edinburgh using innovative and sustainable engineering biology techniques to valorise waste,” she said. “These techniques could help bring about a green revolution in industrial manufacture in the UK and beyond, and we would urge companies interested in working with us to get in touch.”
Douglas Martin, Founder and CEO of MiAlgae, said biotechnology had the potential to transform industrial production.
“MiAlgae is using advanced biotechnology techniques to sustainably produce Omega 3s for the aquaculture and pet feed industries. Having recently broken ground on our new plant at Grangemouth, we believe biotechnology can transform industrial processes and build a more sustainable future,” he said.
The University of Edinburgh has stated that tackling climate and environmental emergencies is central to its mission to become carbon neutral by 2040, with sustainable research and innovation forming a key part of that strategy.
