On May 16, 2019 (April 12, 2019 in the lunar calendar), the first organism to completely synthesize and completely change the DNA code was born. According to a study published in Nature on May 16, Beijing time, scientists at the University of Cambridge in the United Kingdom have successfully created the world's first fully synthetic and completely changed DNA code in the laboratory. It is Escherichiacoli, a bacterium ubiquitous in soil and the human gut that is similar to its natural relatives but survives on a smaller set of genetic instructions. The existence of this bacterium proves that life can exist in a limited genetic code, and paves the way for biosynthetic drugs, materials, or the addition of new properties such as virus resistance. After two years of work, researchers at the University of Cambridge's Molecular Biology Laboratory read and redesigned the DNA of E. coli and then created cells from synthetic versions of the altered genome. The artificial genome contains 4 million base pairs, and the genetic code consists of the letters G, A, T and C. The base pairs, if printed in their entirety on A4 paper, would be 970 pages long. It is the largest genome scientists have built to date. Jason Chin, a synthetic biology expert who led the project, said: "It is completely unclear whether it is possible to make a genome this big, and whether it is possible to change it that much." The DNA coiled inside the cell holds the instructions the cell needs to function. For example, when a cell needs more protein to grow, it reads the DNA that encodes the correct protein. DNA letters are made up of three triplets called codons, such as TCG and TCA. Nearly all life, from jellyfish to humans, uses 64 codons, but many of them do the same job. In total, 61 codons give rise to 20 natural amino acids. These amino acids can be strung together like beads to build various proteins found in nature. The other 3 codons are actually stop signals, and they tell the cell when the protein is done, like a period at the end of a sentence. New synthetic biology EscherichiacoliSyn61 The research team redesigned the genome of E. coli by removing some of the extra codons. Working on the computer, they scrutinized E. coli's DNA. Whenever they encountered TCG (an amino acid codon that makes serine), they rewrote it to AGC, and so on, they systematically replaced the other two codons. Image credit: Nature After 18,218 edits, scientists have removed three codons from the bacterium's genome for each occurrence. The redesigned genetic code was then chemically synthesized and added to E. coli piece by piece, replacing its natural genome. Scientists say it is a microbe with a fully synthetic and radically altered DNA code. The synthetic organism, Syn61, is slightly longer than normal and grows at a slower rate, but still survives. "It's incredible! When the bacteria was created shortly before Christmas, the research team took a picture in the lab recreating the birth of Jesus with a plate of microbes as the central figure," says Chin. Sooner or later, Chin believes, such engineered life forms will come in handy. Because of their different DNA, invading viruses will have difficulty spreading within their bodies, making them actually resistant to viruses. Today, E. coli is used by the biopharmaceutical industry to make insulin for diabetes and other pharmaceutical compounds that treat cancer, multiple sclerosis, heart disease and eye diseases. But when bacterial cultures are contaminated with viruses or other microbes, the entire production process can be disrupted. But that's not all. In future work, these released genetic codes could be repurposed to allow cells to mass-produce designer enzymes, proteins and drugs. In 2010, US scientists announced the creation of the world's first synthetic genome. The bacteria, called Mycoplasma genitalium, has a genome smaller than E. coli, about 1 million base pairs, and has not undergone a complete redesign. Credit: "Science" Commenting on the latest work, Clyde Hutchison of the US research team said that the scale of this genome replacement is larger than any complete genome reported so far. "This research takes the field of synthetic genomics to the next level," says Tom Ellis, a synthetic biology researcher at Imperial College London. "Not only has it succeeded in building the largest synthetic genome to date, but it has also achieved the highest level of coding changes to date." But those records may not last long. Ellis and other scientists are building a synthetic genome for baker's yeast, while Harvard scientists are creating more bacterial genomes with coding changes. "It's not surprising that the redesigned E. coli can't grow like a natural strain," adds Ellis. "If there's anything amazing, it's that it's still growing after so many changes." China Biotechnology Network sincerely invites scientists in the field of biology to publish and introduce original scientific research results at home and abroad on our platform.