First replicating bacterial cell with synthetic DNA
20 May 2010
Scientists at the J. Craig Venter Institute (JCVI) in the US,
have created the the first self-replicating bacterial cell with
It is the result of 15 years of genetics research at the Institute and involved mapping the genome of the bacteria
Mycoplasma mycoides, designing a new genome in a computer,
chemically synthesizing the 1.08 million base pair chromosome of
this genome, and transplanting this into modified cells of another
bacteria, Mycoplasma capricolum. The DNA was synthesised
from just raw chemicals using a yeast DNA-assembly system designed
by the institute. The new bacteria contains only the synthetic DNA
so is named after the origin of this DNA — Mycoplasma mycoides JCVI-syn1.0.
The research is published in the 20 May edition of Science
Express and will appear in an upcoming print issue of
The Institute says that throughout the research it has also
commissioned independent social and ethical reviews of its research,
which concluded that there were no strong ethical reasons why the
work should not continue as long as the scientists involved
continued to engage public discussion.
To complete this final stage in the nearly 15-year process to
construct and boot up a synthetic cell, JCVI scientists began with
the accurate, digitized genome of the bacterium, M. mycoides.
The team designed 1,078 specific cassettes of DNA that were 1,080
base pairs long. These cassettes were designed so that the ends of
each DNA cassette overlapped each of its neighbours by 80 base
pairs. The cassettes were made according to JCVI’s specifications by
the DNA synthesis company, Blue Heron Biotechnology.
The JCVI team employed a three stage process using their
previously described yeast assembly system to build the genome using
the 1,078 cassettes. The first stage involved taking 10 cassettes of
DNA at a time to build 110, 10,000 bp segments. In the second stage,
these 10,000 bp segments are taken 10 at a time to produce eleven,
100,000 bp segments. In the final step, all 11, 100 kb segments were
assembled into the complete synthetic genome in yeast cells and
grown as a yeast artificial chromosome.
The complete synthetic M. mycoides genome was isolated from the
yeast cell and transplanted into Mycoplasma capricolum recipient
cells that have had the genes for its restriction enzyme removed.
The synthetic genome DNA was transcribed into messenger RNA, which
in turn was translated into new proteins. The M. capricolum genome
was either destroyed by M. mycoides restriction enzymes or was lost
during cell replication. After two days viable M. mycoides cells,
which contained only synthetic DNA, were clearly visible on petri
dishes containing bacterial growth medium.
The initial synthesis of the synthetic genome did not result in
any viable cells so the JCVI team developed an error correction
method to test that each cassette they constructed was biologically
functional. They did this by using a combination of 100 kb natural
and synthetic segments of DNA to produce semi-synthetic genomes.
This approach allowed for the testing of each synthetic segment
in combination with 10 natural segments for their capacity to be
transplanted and form new cells. Ten out of 11 synthetic fragments
resulted in viable cells; therefore the team narrowed the issue down
to a single 100 kb cassette. DNA sequencing revealed that a single
base pair deletion in an essential gene was responsible for the
unsuccessful transplants. Once this one base pair error was
corrected, the first viable synthetic cell was produced.
“For nearly 15 years Ham Smith, Clyde Hutchison and the rest of our
team have been working toward this publication today — the
successful completion of our work to construct a bacterial cell that
is fully controlled by a synthetic genome,” said Dr J Craig Venter,
founder and president, JCVI and senior author on the paper. “We have
been consumed by this research, but we have also been equally
focused on addressing the societal implications of what we believe
will be one of the most powerful technologies and industrial drivers
for societal good. We look forward to continued review and dialogue
about the important applications of this work to ensure that it is
used for the benefit of all.”
According to Dr Smith, “With this first synthetic bacterial cell
and the new tools and technologies we developed to successfully
complete this project, we now have the means to dissect the genetic
instruction set of a bacterial cell to see and understand how it
Dr. Gibson stated, “To produce a synthetic cell, our group had to
learn how to sequence, synthesize, and transplant genomes. Many
hurdles had to be overcome, but we are now able to combine all of
these steps to produce synthetic cells in the laboratory.” He added,
“We can now begin working on our ultimate objective of synthesizing
a minimal cell containing only the genes necessary to sustain life
in its simplest form. This will help us better understand how cells
This publication represents the construction of the largest
synthetic molecule of a defined structure; the genome is almost
double the size of the previous Mycoplasma genitalium
synthesis. With this successful proof of principle, the group will
now work on creating a minimal genome, which has been a goal since
1995. They will do this by whittling away at the synthetic genome
and repeating transplantation experiments until no more genes can be
disrupted and the genome is as small as possible. This minimal cell
will be a platform for analyzing the function of every essential
gene in a cell.
According to Dr. Hutchison, “To me the most remarkable thing
about our synthetic cell is that its genome was designed in the
computer and brought to life through chemical synthesis, without
using any pieces of natural DNA. This involved developing many new
and useful methods along the way. We have assembled an amazing group
of scientists that have made this possible.”
As in the team’s 2008 publication in which they described the
successful synthesis of the M. genitalium genome, they
designed and inserted into the genome what they called watermarks.
These are specifically designed segments of DNA that use the
“alphabet” of genes and proteins that enable the researcher to spell
out words and phrases. The watermarks are an essential means to
prove that the genome is synthetic and not native, and to identify
the laboratory of origin.
Encoded in the watermarks is a new DNA code for writing words,
sentences and numbers. In addition to the new code there is a web
address to send emails to if you can successfully decode the new
code, the names of 46 authors and other key contributors and three
quotations: "TO LIVE, TO ERR, TO FALL, TO TRIUMPH, TO RECREATE LIFE
OUT OF LIFE." - JAMES JOYCE; "SEE THINGS NOT AS THEY ARE, BUT AS
THEY MIGHT BE.” - A quote from the book, “American Prometheus”; "WHAT
I CANNOT BUILD, I CANNOT UNDERSTAND." - RICHARD FEYNMAN.
The JCVI scientists envision that the knowledge gained by
constructing this first self-replicating synthetic cell, coupled
with decreasing costs for DNA synthesis, will give rise to wider use
of this powerful technology. This will undoubtedly lead to the
development of many important applications and products including
biofuels, vaccines, pharmaceuticals, clean water and food products.
The group continues to drive and support ethical discussion and
review to ensure a positive outcome for society.
Funding for this research came from Synthetic Genomics Inc., a
company co-founded by Drs. Venter and Smith.
1. See also the BJHC&IM article:
Artificial life impossible without computers
2. The J Craig Venter Institute: