This engineered genome will help experts tailor organisms to fit the needs of their ever-changing environments.

• For the first time ever, a synthetic eukaryotic genome has been created.
• By taking yeast cells and rebuilding their genomes, scientists were able to create a yeast that more resilient and produced more spores—something that could mean more food on a much larger scale
• Creating synthetic genomes could eventually make sustainable manufacturing processes that use eukaryotic bacteria more efficiently.

While the concept of creating synthetic life from nothing is still firmly in the science fiction category, synthetic genomes are now reality. Researchers—led by synthetic biologist Hugh Goold of Macquarie University in Australia—have created the first synthetic eukaryotic genome for a species of yeast. Previous experiments had been done on prokaryotes (single-celled organisms that lack a nucleus), but a full synthetic genome had not been reconstructed for any single-celled eukaryotic organisms (which have a nucleus and organelles with distinct functions).

This synthetic genome tech means that life-forms can be customized depending on what aspects need to be enhanced. As part of the Sc2.0 Project, for example, the yeast Saccharomyces cerevisiae was redesigned and reconstructed to produce more spores and keep from mutating (since this yeast is prone to spontaneous mutations) as it grew.

This genomic makeover was a decade in the making. Also known as brewer’s yeast, Saccharomyces cerevisiae has a long history of being used in brewing, winemaking, and baking. Reconstructing its genome would not only give it the qualities it needs to resist disease and survive climate change, but allow it to yield a higher quantity and quality of food while maintaining sustainability.

“The technology of synthetic genomics can help to secure supply chain in future situations where changing climates, further global pandemics, and conflict threatens the availability of critical and conventional feedstocks of food and pharmaceuticals,” the researchers said in a study recently published in Nature.

To create a specific synthetic chromosome within the synthetic genome, Goold started with several strains of S. cerevisiae, which had already had synthetic pieces of DNA inserted. These were backcrossed—a process which involves mating genetically different parent cells to create hybrid offspring, which are then mated with the parent cells. Backcrossing may sound like inbreeding, but actually makes it easier to isolate any characteristics that may require a closer look.

The strain with the newly created synthetic chromosome, SynXVI, suffered impaired growth and often mutated. More backcrossing allowed the team to identify which areas of SynXVI were glitching. Why were there issues with a genome that was supposed to be version 2.0 of the original? It turned out that errors in placing genetic markers—genes or short sequences of DNA that are used to identify genes and chromosomes inside a genome—sometimes interfered with the function of yeast cells.

Genetic glitches in the chromosome were identified and edited with CRISPR D-BUGS (which sounds like some sort of futuristic pest killer) and other genetic tools that were able to zero in on specific areas of the genome and correct them. Boosting yeast growth and resilience meant getting it to grow on glycerol (a carbon source) to absorb the carbon it needed at a certain temperature. It turned out that one section of the genome was causing a deficit of copper, but this was easily solved by adding copper sulfate to the glycerol.

Despite the glitches, this technology opens up opportunities for creating more than better crops. Eukaryotic microbes already used in sustainable manufacturing processes could be modified to become even more efficient.

“S. cerevisiae holds great potential in libraries of new chromosomes,” the researchers said in the same study, “[including] neochromosomes, and genomes for subsequent transfer into cells to create life forms tailored to humankind’s needs.”

Someday, maybe even artificial mammalian genomes could be created, But for now, just one yeast is offering so many possibilities.