In the fairy tale Hansel and Gretel, the children’s use breadcrumbs to lay a path back out of the woods. That might not have gone as expected, but now breadcrumbs could create a path to free the chemical industry from much of its fossil fuel use.
Researchers at the University of Edinburgh have now developed a technique to cut out fossil fuels from one of the chemical industry’s most widely used reactions. The method, which uses microbes and waste bread, is carbon negative: it removes more greenhouse gases than it produces. The process could open up new routes for bio-based manufacturing using waste feedstocks, the team writes in the journal Nature Chemistry.
The chemical industry uses hydrogenation widely to make food products, pharmaceuticals, plastics and many other everyday products. But the hydrogen needed for this chemical synthesis is currently produced by the steam reforming of coal. The process emits 15–20 kilograms of carbon dioxide equivalent per kg of hydrogen.
Efforts to make chemical hydrogenation greener in recent years have focused on splitting water by electrolysis to free hydrogen. But large-scale electrolysis reactors are energy-intensive and not very energy-efficient.
So the Edinburgh team turned to an age-old route to hydrogenation found in nature. Microbes such as bacteria produce hydrogen when they feed on sugary or waste feedstocks.
The researchers feed a common laboratory strain of E. coli bacteria with sugars extracted from waste bread. They grow the microbes in an environment that lacks oxygen. Under these conditions, the bacteria naturally feed on the bread and produce hydrogen gas.
Then, the researchers add a small amount of palladium catalyst and another chemical to the reaction flask. They found that the hydrogen generated by the microbes was enough to drive hydrogenation reactions. The process occurs at near-room temperature, and does not need any fossil fuels or added hydrogen gas.
Because the process avoids the use of fossil fuels and uses waste foodstuff—keeping it from landfill where it would release methane or from being burned and releasing carbon dioxide—it is carbon negative, the researchers’ detailed analysis shows.
“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,” said lead author and professor of chemical biotechnology Stephen Wallace in a press release.
Source: Mirren F. M. White et al. Native H2 pathways enable biocompatible hydrogenation of metabolic alkenes in bacteria. Nature Chemistry, 2026.
Image: ©Anthropocene Magazine
