Technologya.am (July 26, 2009) — US scientists have engineered bacteria that can solve complex mathematical problems faster than anything made from silicon.
The researchers wanted to prove that bacteria can be used to solve a puzzle known as the Hamiltonian Path Problem. If you want to tour the 10 biggest cities in the UK, starting in London (number 1) and finishing in Bristol (number 10). The solution to the Hamiltonian Path Problem is the shortest possible route you can take.
This simple problem is surprisingly difficult to solve. There are over 3.5 million possible routes to choose from, and a regular computer must try them out one at a time to find the shortest. Alternatively, a computer made from millions of bacteria can look at every route simultaneously. The biological world also has other advantages. As time goes by, a bacterial computer will actually increase in power as the bacteria reproduce.
The researchers coded a simplified version of the problem, using just three cities, by modifying the DNA of Escherichia coli bacteria. The cities were represented by a combination of genes causing the bacteria to glow red or green, and the possible routes between the cities were explored by the random shuffling of DNA. Bacteria producing the correct answer glowed both colours, turning them yellow.
The scientists checked the yellow bacteria’s answer by examining their DNA sequence. By using additional genetic differences such as resistance to particular antibiotics, the team believes their method could be expanded to solve problems involving more cities.
The researchers have previously built a bacterial computer to solve the Burnt Pancake Problem. This is a mathematical sorting process that can be visualised as a stack of pancakes, all burnt on one side, which must be ordered by size.