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Soil bacteria produce proteins and pharmaceuticals from carbon dioxide

23 December 2022

A bacterium that can grow on a mixture of carbon dioxide, oxygen, and hydrogen can be persuaded to produce various useful products, such as amino acids, milk proteins, and building blocks for pharmaceuticals. Sandy Schmidt, a biochemist at the University of Groningen, wants to grow this bacterium in a bioreactor that is fed waste gases from factories, to turn carbon dioxide into valuable molecules.

The bacterium Cupriavidus necator was originally isolated from soil near the German town of Göttingen and was, so far, famous for its ability to produce bioplastics. Sandy Schmidt, an Assistant Professor at the Groningen Research Institute of Pharmacy (University of Groningen, the Netherlands) wants to use this microorganism in a different way. ‘It usually grows on sugar, but it can be fed a mixture of carbon dioxide, oxygen, and hydrogen gases,’ explains Schmidt. ‘My idea is to grow it on waste gases from the chemical industry or steel works and to make it produce various useful molecules.’

Sandy Schmidt| Photo Reyer Boxem
Sandy Schmidt| Photo Reyer Boxem

Cheese

By tweaking the bacterium’s metabolic pathways, it is possible to overproduce, for example, the amino acid lysine, an important component of animal feed. ‘And we are conducting research for a company that wants to make vegan cheese,’ says Schmidt. ‘For this, our bacterium must make milk proteins.’ She has already achieved some milk protein production; however, new genetic tools are needed for the lysine project. ‘Cupriavidus necator is not widely used in science and, therefore, very few tools to adapt its genome have been developed.’

Schmidt has been working on these projects for about two years and expects some tangible results in the next two to three years. ‘By then, we should have strains that produce large quantities of the required products. However, the next step—upscaling the bioreactors to industrial size—might take another five years.’ Apart from the upscaling, the gas mixture she wants to feed the bacteria contains oxygen and hydrogen–a very explosive combination. ‘Solutions to do this safely are being investigated at the moment’

Waste gases

If all goes well, bioreactors could be placed next to steel works or chemical plants, such as Tata Steel or BASF. Schmidt: ‘The waste gases of these factories may also contain sulphur or heavy metals, but our bacterium is fairly resistant against such pollutants, so we don’t have to purify the gases very much.’ One downside to her superbug is that it smells horrible. ‘Students who first get to work with it are really put off by that smell.’

The microorganism Cupriavidus necator can grow on a mixture of oxygen (O2), hydrogen (H2) and carbon dioxide (CO2). It uses an enzyme called RuBisCo to fix CO2, and an enzyme called hydrogenase to generate energy for its growth. By adapting its genome and metabolism, and adding additional enzymes (biocatalysts) to the cells, valuable chemicals can be produced by the microorganism directly from CO2. | Illustration Sandy Schmidt
The microorganism Cupriavidus necator can grow on a mixture of oxygen (O2), hydrogen (H2) and carbon dioxide (CO2). It uses an enzyme called RuBisCo to fix CO2, and an enzyme called hydrogenase to generate energy for its growth. By adapting its genome and metabolism, and adding additional enzymes (biocatalysts) to the cells, valuable chemicals can be produced by the microorganism directly from CO2. | Illustration Sandy Schmidt

Pharmaceuticals

Despite these drawbacks, Cupriavidus necator appears to have the potential to be a goose with golden eggs. Apart from amino acids and proteins, it can produce building blocks for pharmaceuticals. It is also used to make compounds that are labelled with the carbon-13 isotope, which can be used in medical diagnostics and magnetic resonance studies.

Schmidt is keeping an eye on FutureCarbonNL (a collaboration of Dutch universities, including the University of Groningen, knowledge institutes, chemical and other industries, SMEs, and start-ups), which has submitted a multi-million Euro proposal to the Dutch Nationaal Groeifonds, money that is to be used for investment in carbon capture research. With this proposal is funded, she might be able get extra funding for her work to produce cheese and drugs from factories’ waste gases.

Last modified:23 December 2022 11.37 a.m.
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