According to a report on the website of Le Monde on March 27, biotechnology experts are using greenhouse gas carbon dioxide to produce bioplastics. A team led by Li Xiangye and Li Xianzhu of the Korean Academy of Science and Technology reported in the Journal of the National Academy of Sciences that polyester produced through this technology is compatible with biological tissues and can be biodegradable.
"If a biotechnology factory relies on renewable energy for electricity, the production of plastics is climate neutral.". "The use of renewable energy to convert carbon dioxide generated by humans into value-added products to achieve a sustainable carbon cycle has received widespread attention," the researchers wrote
It has been known that the copper voracious bacteria can produce polyhydroxybutyrate (PHB). However, previous yields were small. The research team has now found that electrochemical conversion of carbon dioxide and production of PHB in two separate containers can optimize this biotechnology process.
In a container, carbon dioxide is reduced to formic acid on a gas diffusion electrode. However, this process generates electrical currents and oxides and nitrides that are harmful to bacterial cells. The researchers created better growth conditions for the bacterium by transferring its fermentation to another container. However, for this reason, they must develop an electrolyte that can both electrochemically react with carbon dioxide and enable bacterial cells to mass-produce bioplastics.
The team successfully developed such an electrolyte that it was possible to establish a cycle in which formic acid was continuously generated in the container of a carbon dioxide electrolysis device and flowed into the fermentation container along with the electrolyte, while filtering out substances harmful to the bacteria. In a fermentation vessel, bacteria use formic acid as a food source to produce PHB, which continuously accumulates in bacterial cells. Biotechnology experts have achieved PHB production equivalent to 83% by mass of bacterial solid components.
The insecticidal copper greedy bacteria removed from the fermentation vessel will be replaced by newly cultured bacteria. After the bacterial cells are filtered out, the electrolyte will also flow back into the container of the carbon dioxide electrolysis device.
The author of the study wrote, "This work provides an unusual strategy for reducing carbon dioxide emissions and producing environmentally friendly bioplastics." The process has been running steadily for 18 days, with formic acid and PHB concentrations consistently unchanged. Therefore, the researchers believe that they can expand the process to commercial production scale of PHB.
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