Smallest ever mobile lifeform created — opening the door to disease-curing microrobots

OSAKA, Japan — Scientists have created the smallest ever mobile lifeform, opening the door to curing diseases with cell-mimicking robots.

Scientists in Japan inserted the tiny genome, containing DNA an organism needs to survive and function, into an empty cell. It also sheds fresh light on how cell motility arose during evolution. Walking, swimming, or flying can be traced back to cellular movements.

The stripped-down genome has been established with the help of a simple bacterium, called Spiroplasma. The Japanese team introduced seven proteins to enable it to swim into a synthetic bacterium named syn3.

Through genetic engineering, syn3 was designed and chemically synthesized to have the least DNA possible. This included the minimum essential genetic information required for growth from the smallest genomes of naturally occurring Mycoplasma bacteria.

“Studying the world’s smallest bacterium with the smallest functional motor apparatus could be used to develop movement for cell-mimicking microrobots or protein-based motors,” says lead author Professor Makoto Miyata of Osaka Metropolitan University in a media release.

syn3 robot
Osaka Metropolitan University researchers have made the mobile lifeforms that have the smallest genome so far. They introduced seven proteins, thought to let Spiroplama bacteria swim by spiraling, into a strain of synthetic bacteria. The small spherical synthetic bacteria have minimal genetic information, allowing them only to grow and divide. With the expression of these additional proteins, the synthetic bacteria formed helices and were capable of swimming, making them the smallest mobile lifeforms genetically. (CREDIT: Makoto Miyata, Osaka Metropolitan University)

The small, spherical synthetic bacteria can grow and divide. The synthetic bugs formed helices — making them the smallest lifeforms genetically. Re-engineered syn3 changed from its normal spherical shape into a spiraling helix, which was able to swim by reversing the helix’s direction just like Spiroplasma.

Further investigation revealed that only two of these newly added proteins were required to make syn3 capable of minimal swimming.

“Our swimming syn3 can be said to be the ‘smallest mobile lifeform’ with the ability to move on its own,” says Prof. Miyata. “The results of this research are expected to advance how we understand the evolution and origins of cell motility.”

The artificial organism is not an example of creating life from scratch but a slightly modified copy of an existing genome. It also offers hope of modifying genes to mop up greenhouse gases. Other tasks such organisms might be able to do include cleaning up oil spills or producing plastics.

New lifeforms may even look at the more fundamental question of the origins of life. The technology could also have biomedical applications. Cells could be used as factories to make drugs or fabricate structures.

Syn3 is described in the journal Science Advances.

South West News Service writer Mark Waghorn contributed to this report.

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