Cell: genetically engineered E.coli can also grow through carbon dioxide

In a new study, researchers from the weizman Institute of Science in Israel genetically engineered E.coli to grow by absorbing carbon dioxide The relevant research results were recently published in the journal Cell, and the title of the paper is "conversion of Escherichia coli to generate all biomass carbon from CO2" Picture from cell, 2019, DOI: 10.1016/j.cell.2019.11.009 E.coli is usually heterotrophic, that is, taking glucose and other organic compounds as food organics, but this new study shows that they can be transformed into autotrophs, absorbing carbon dioxide from the atmosphere and converting it into biomass Dave savage, a biochemist at the University of California, Berkeley, who was not involved in the new study, said, "it's amazing how quickly and thoroughly an organism that has been heterotrophic for billions of years can be transformed into an autotroph This suggests that metabolism is highly plastic " According to Ron Milo, a systems biologist at the Weizmann Institute of science and technology, the process of using inorganic carbon to produce biomass is called carbon fixation, which can be used to solve some of the biggest challenges facing mankind today For example, increasing carbon fixation in plants can produce more biomass, which may increase the world's food supply Milo said his team set out to get E.coli, a model organism with a high degree of genetic plasticity, to fix carbon as a step toward a sustainable industrial process (making biofuels) E.coli usually does not use the molecular mechanism of carbon dioxide, so these researchers introduce carbon fixing genes into Pseudomonas according to its gene sequence which can fix carbon These changes are not enough to force E.coli to become an autotroph, so they also disable three genes involved in heterotrophic metabolism in the bacteria, and put them into a growth chamber with limited sugar content, which makes them starve In this environment, E.coli, which uses carbon dioxide instead of a limited sugar supply, has an advantage The researchers wanted to know if E coli could evolve to use only carbon dioxide These genetically modified E coli grow on the basis of sodium formate Sodium formate is a carbon molecule that provides the necessary electrons in the process of energy generation, but does not contribute to biomass The air in the growth chamber is also rich in carbon dioxide After about 200 days, the genetically engineered E coli relies entirely on carbon dioxide in the air to produce biomass, while using formate as an essential component of the chemical reaction When the researchers analyzed the E coli genome, they found that the bacteria evolved into carbon dioxide - only autotrophs after at least 11 mutations Some of these mutations occur in genes related to carbon fixation, while others occur in genes known to have mutations in other laboratory evolutionary experiments or to have no known role in the production of biomass using carbon dioxide Tobias Erb, a synthetic biologist at the Institute of terrestrial microbiology in Max Planck, Germany, published a review of the new study "It's a proof of concept in this area that you can really reinvent the metabolic characteristics of living organisms from scratch," he said This is an exciting step forward " But, he said, "if they build a strain that has biotechnological significance in the future.. I think it's open to question." For example, autotrophic E coli currently produces more carbon dioxide as a byproduct than they absorb This can be solved by using carbon dioxide to produce formates in the future, so as not to generate net carbon dioxide emissions In addition, the researchers used high levels of carbon dioxide - about 10% of the atmosphere in the growing chamber, but only 0.04% of the earth's atmosphere "We would like to know if we can reduce it to the level of carbon dioxide in the environmental atmosphere, which means that people can use the environmental atmosphere with a much lower carbon dioxide content (400 ppm)," Milo said "Today, it's an interesting concept," said Patrik Jones, who conducted research on microbial metabolic engineering at Imperial College in the UK, who was not involved in the new study This is definitely a step in that direction But I think it's important to recognize that more research is needed to use it "