Gladstone Institutes researchers have extended retron based genome editing (recombitrons) beyond E. coli to 15 bacterial species across three phyla, ending a 25 year dependency on the single workhorse organism. By designing 10 different recombitron versions and distributing them…
E. coli has been the universal workaround for bacterial genome editing for 25 years. That detour is over.
A team at the Gladstone Institutes has extended retron-based genome editing called recombitrons from a single workhorse organism to 15 bacterial species spanning three major phyla, according to a paper published in Nature Biotechnology. The work, led by senior author Seth Shipman and first author Alejandro González-Delgado, demonstrates that recombitrons function in every species tested, including drug-resistant pathogens and industrial biotech strains that were previously genetically unwritable.
For decades, synthetic biologists who wanted to edit bacterial genomes had essentially one option: route the work through E. coli. Recombineering, a precision genome editing technique developed in E. coli in 2000, worked beautifully there but nowhere else. Researchers studying Klebsiella pneumoniae, Vibrio natriegens, or the gut microbiome had to first engineer their target organism's genes into E. coli, make the edit, and hope the result transferred back. "We kept hearing from the broader field, asking when there would be a version of this technology that could be put to work in other bacterial species that matter for the environment, industrial processes, or human health," Shipman said.
The new study aimed to answer that question at scale. The team designed 10 different recombitron versions — molecular editing modules pairing retron DNA-production machinery with single-stranded binding and annealing proteins — and shipped them to nine external laboratories for testing across phylogenetically distant bacterial species. The results: recombitrons worked in all 15 species. Editing efficiencies varied, reaching above 90% in two organisms, above 40% in three, and above 20% in six others, per the paper's abstract.
What explains the variation? Each retron behaved differently in each bacterium. "Each retron worked differently in different bacteria," González-Delgado noted in GEN News. "This reinforces why it's important to have lots of different retrons, so scientists can choose the ones best suited to their favorite bacterial species." The solution was designing a large toolkit rather than hunting for a universal version.
The practical implications cut across several domains. Klebsiella pneumoniae and Pseudomonas aeruginosa, both drug-resistant pathogens, are now editable, opening new avenues for studying virulence and resistance mechanisms. Vibrio natriegens, one of the fastest-growing bacteria known, becomes a more practical biomanufacturing chassis. Pseudomonas putida, already used in industrial biotechnology, gains a precision engineering path.
Retrons themselves are bacterial immune elements: viral defense systems that naturally produce short DNA fragments inside cells. Shipman's lab has spent years repurposing this machinery, as documented in earlier Gladstone work. In E. coli, retrons had already enabled molecular recording, phage editing, and multiplexed genome engineering. The new work extends that toolkit to the rest of the bacterial kingdom.
Not every species reached high editing efficiency on the first pass. But the paper shows the architecture is portable — and where initial efficiency was low, tweaking retron structure or strain background lifted performance. "My lab builds molecular technology, and we want these technologies to be used as broadly as possible to uncover new biology and intervene in disease," Shipman said. "We hope it will continue to spread from here."
Whether it spreads depends partly on whether the broader synthetic biology community adopts recombitrons as a standard tool. The E. coli monoculture in bacterial engineering is a legacy of necessity, not preference. If this paper sticks, that necessity evaporates.