Did you know that genetically engineered bacteria can do math?

In an astonishing breakthrough, scientists in India have genetically engineered bacteria capable of performing mathematical operations. Researchers from the Saha Institute of Nuclear Physics (SINP) in Kolkata have demonstrated that clusters of bacterial cells can add, subtract, and even identify prime numbers between 0 and 9. This accomplishment marks a crucial step toward the development of biocomputers—computational devices made from living cells that could revolutionise how we think about computing in the future.

A history of biological computing

The concept of using living cells for computation is not entirely new. Over the past two decades, researchers worldwide have explored the potential of biological systems to perform computational tasks. The first major breakthroughs came in the early 2000s when scientists developed synthetic biology techniques to engineer cells with logic gates—the fundamental components of digital computers. These biological logic gates allowed simple operations such as "AND," "OR," and "NOT," mimicking the operations seen in silicon-based processors.

Following this, scientists advanced by using various microbes, such as E. coli and yeast, to perform basic mathematical operations like addition and subtraction. Researchers were able to construct networks of genes and proteins within the cells, programming them to respond to specific chemical inputs. While these early studies were promising, the computational tasks performed by cells were relatively simple and far from rivalling the capabilities of modern microprocessors.

However, SINP's latest research takes a significant step forward by using a more sophisticated approach. The integration of artificial neural network concepts with genetic engineering enabled these bacterial cells to solve more complex and abstract problems, such as identifying prime numbers — tasks traditionally considered the domain of human brains or advanced computers.

Turning bacteria into living machines

The research team modified the E. coli genomes, incorporating 14 distinct genetic circuits, to create different bacterial types. These bacteria can be combined and arranged in liquid environments to execute various computational functions. In one set of experiments, the scientists were able to get them to add, subtract, and solve ten different computational problems, including determining prime numbers between 0 and 9.

The bacteria's ability to answer yes-or-no questions, like "Is 4 a prime number?" or "Is 7 a prime number?" was particularly astonishing. When the bacteria were questioned chemically, they responded by secreting proteins that indicated their answers — green for "yes" and red for "no." This development underscores their capacity to function as living computers.

The implications of this research are immense, not only for computational science but also for fundamental biology. “Mammalian cells make decisions all the time, and we currently have very little understanding of this decision-making process,” said Mohit Kumar Jolly, assistant professor at the Indian Institute of Science, Bangalore. This study offers fresh insights into biological decision-making and could open new avenues for understanding how living organisms process information.

As scientists continue to explore the computational power of living cells, the possibilities are endless. Bacteria, once considered simple organisms, may well hold the key to the future of computing.