In Israel, scientists at the Weizmann Institute of Science were able to get bacteria to eat carbon dioxide from their environment – essentially building all of their biomass from air. This feat involved nearly a decade of rational design, genetic engineering and a sped-up version of evolution in the lab. The findings point to means of developing, in the future, carbon-neutral fuels.
The study began by identifying crucial genes for the process of carbon fixation – the way plants take carbon from CO2 for the purpose of turning it into such biological molecules as protein, DNA, etc. The research team added and rewired the needed genes. They found that many of the “parts” for the machinery that were already present in the bacterial genome could be used as is. They also inserted a gene that allowed the bacteria to get energy from a readily available substance called formate that can be produced directly from electricity and air and which is apt to “give up” electrons to the bacteria.
Just giving the bacteria the “means of production” was not enough, it turned out, for them to make the switch. There was still a need for another trick to get the bacteria to use this machinery properly, and this involved a delicate balancing act.
“Our lab was the first to pursue the idea of changing the diet of a normal heterotroph (one that eats organic substances) to convert it to autotrophism (‘living on air’),” says Milo. “It sounded impossible at first, but it has taught us numerous lessons along the way, and in the end we showed it indeed can be done. Our findings are a significant milestone toward our goal of efficient, green scientific applications.”