Bacteria could become tiny but powerful allies against climate change, a new study shows. Researchers have engineered microbes to produce carbon-based chemicals that are used as a feedstock to make fuels, drugs and industrial chemical products.
The advance, reported in the journal Nature, creates a sustainable path to make these important products with a lower carbon footprint and cost than is possible today using traditional methods.
Nearly half of all greenhouse gas emissions today come from the production of chemicals, iron and steel, and cement. Decarbonizing these big industrial sectors is necessary if we are to limit global warming to 1.5 degrees Celsius above pre-industrial levels.
For the chemical industry, that means coming up with manufacturing processes that do not rely on fossil fuels. Using bacteria to synthesize chemicals is a solution. The concept, called biosynthesis, is an “environmentally benign and renewable approach that can be used to produce a broad range of natural and, in some cases, new-to-nature products,” the team from the University of California, Berkeley and Lawrence Berkeley National Laboratory write in the paper.
Scientists have, for instance, engineered microbes to produce ammonia fertilizer, and key ingredients for making nylon and other plastics. The problem is that biology lacks many of the reactions that are available to synthetic chemists. So using biosynthesis gives a narrower range of products than synthetic chemistry.
One such important product is a family of highly reactive molecules called carbenes. Carbenes are used in catalysts that expedite chemical reactions used to produce pharmaceuticals, fuels and other chemicals. Making carbenes takes a lot of energy and expensive chemical substances, however, and is so far done in small batches.
So the Berkeley team have now coaxed bacteria to produce carbenes. They started with a bacteria called Streptomyces albus and insert a cluster of genes into the microbes. The engineered bacteria digest and convert sugars into a carbene building block. What’s more, the bacteria also expressed an evolved enzyme that used that building block to produce cyclopropanes, high-energy molecules that could potentially be used in the sustainable production of novel bioactive compounds and advanced biofuels.
“We can synthesize everything in this reaction—from natural enzymes to carbenes—inside the bacterial cell,” said Jay Keasling, a principal investigator of the study and CEO of the US Department of Energy’s Joint BioEnergy Institute (JBEI). “All you need to add is sugar and the cells do the rest.”
The work expands the scope of organic products that can be produced by biosynthesis, the researchers write. Plus, said Keasling, “the cells produce all of the reagents and the cofactors, which means you can scale this reaction to very large scales.”
Source: Huang, J., Quest, A., Cruz-Morales, P. et al. Complete integration of carbene-transfer chemistry into biosynthesis. Nature, 2023.
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