\u2018We wanted to know how deeply you could compress the genetic code, because if you can compress it, you can then free up some of the previously redundant codons to repurpose them for a new application,\u2019 explains Wes Robertson<\/a>, a synthetic biologist at the LMB and co-leader of the project. \u2018The idea is we can then use cells to make things that chemists used to make in a flask, but now we can do it in a more programmable [and] bio-sustainable way.\u2019<\/p>\n To do this, the team started by developing a recoding scheme that would free up seven codons in the E. coli genome; four of the six codons which encode the amino acid serine, two of the four codons for the amino acid alanine and one stop codon. In total, this meant making more than 100,000 codon changes across the 4 million base pair genome of E. coli.<\/p>\n To make the task more manageable they split the genome up into 38 fragments of around 100,000 base pairs each and synthesised them individually using homologous recombination in yeast to ensure that the recoding scheme would work.<\/p>\n \u2018It worked for about 75% of them. For the 25% where it didn\u2019t work, we then went in and mapped, via a variety of new linkage mapping techniques that we developed,\u2019 says Robertson. \u2018Once we could pinpoint the problems, we added different synthetic DNA designs, which maintained compression, but were slightly different to our original design. \u2019<\/p>\n They then stitched the fragments together, fixing potential problems as they went to enable the next step of the synthesis.<\/p>\n While Syn57 didn\u2019t grow as well as the original strain, Robertson notes that it \u2018grew well enough for us to characterise it in the lab\u2019. He adds that further modifications could provide Syn57 with a \u2018genetic firewall\u2019 that would prevent it interacting with genetic material from the wild-type E. coli. \u2018So this will yield a virus-resistant strain which could be quite useful in industrial purposes,\u2019 he says.<\/p>\n Encoding new chemistry<\/p>\n![\"A](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/08\/542428_syn57_plate_robertson_mrc_lmb_740401_crop.jpg\")
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