Researchers synthesize amino acid without living organism

A lab in Munich has used enzymes to make the amino acid L-alanine without fossil fuels or microorganisms.

Laboratory Microscope Scientist
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Making food or feed from thin air may remain the realm of science fiction, but researchers have begun to remove the need for a living organism from the process.

Researchers at the Technical University of Munich have synthesized the amino acid L-alanine through the use of enzymes, according to a report in the journal Chem Catalysis. Although the technology still needs more work before it will be ready for commercialization, it could one day allow feed producers to create amino acids directly from carbon dioxide and renewable hydrogen and ammonia.

Producers typically rely on fossil fuel resources or microorganisms to make amino acids, says Volker Sieber, a professor at the Technical University of Munich and one of the authors on the Chem Catalysis report. While single-cell protein synthesis is generally considered more sustainable than conventional, fossil fuel-derived amino acids, it still requires glucose to feed the microbes. And creating that glucose biomass still requires acres of land that could otherwise foster greater biodiversity, Sieber said.

“If you want to be really sustainable in what you do ... it’s more important to utilize renewable energy and carbon dioxide,” Sieber said, arguing that a windmill will take up less land than acres of crops.

But if you try to synthesize single-cell proteins using carbon dioxide as a feedstock, the process triggers intermediate chemicals that are toxic to the microorganisms themselves, Sieber said. To get around this barrier, the Technical University of Munich lab removed key enzymes responsible for amino acid synthesis from the microbes to replicate the cellular process outside a living organism.

Using carbon dioxide, hydrogen and ammonia — all preferably from renewable resources, Sieber said — the lab was able to realize a conversion efficiency of nearly 100%. They started with L-alanine on account of its relative simplicity, he said, but have since synthesized other amino acids as well.

Other processes — including microbial synthesis and deriving L-alanine from fossil fuels — remain cheaper than the enzymatic process developed in the lab, Sieber said. But the Technical University of Munich team is now working to refine the process and reduce the cost; Sieber believes if they can speed the action of the enzymes, they will be able to achieve cost parity with other sources of amino acids.

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