An international collaboration of scientists successfully produced a stable artificial strain of bacteria with an extended “genetic alphabet”. The microbe encompasses two additional “X” and “Y” nucleotides, which enable it to store increased information within its genome, laying foundations for new forms of life.

If you´re familiar with elementary school genetics, these news must have rocked you at least a bit. We´ve all been thought that the building blocks of life are based on a four-letter genetic code: Adenine, Guanine, Cytosine and Thymine. By forming natural bonds between each other, these nucleotides make up the DNA double helix, a genetic blueprint for every single living organism on earth – or do they?

An international group of scientists from the US, Europe and China produced a stable semi-synthetic strain of E. coli, modified to integrate two additional X and Y nucleotides, thus forming a six-letter genetic code. Although previous efforts showed that integrating so-called unnatural base pairs (UBP) was possible in microbes, none of them survived for long and lost the UBP rather quickly.

“Your genome isn’t just stable for a day, it has to be stable for the scale of your lifetime. If the semi-synthetic organism is going to really be an organism, it has to be able to stably maintain that information.” said Prof. Floyd E. Romesberg, senior author of the study.

The researchers managed to circumvent previous limitations using a modified nucleotide transporter, which enabled the synthetic nucleotides to be copied across the cell´s membrane. The integration of the UBP was additionally spell-checked using CRISPR-Cas9, which confirmed the team successfully produced the first-ever stable UBP organism. The groundbreaking study was published in the journal PNAS.

So far, the authors state they have no plans to incorporate this technology into multicellular organisms. The next step is to figure out, wheather the new genetic code could also be successfully read and transcribed to RNA. This could jump the number of encoded amino acids within the DNA from 20 to 172, potentially giving rise to new drugs and complex organic material. If successful at that, we might be darn close to actually developing an entirely new form of life, right here on earth.

Learn more about the history of synthetic life in the video bellow:


By Luka Zupančič, MSc, University of Applied Sciences Technikum Vienna