Nobody loves sudoku like my granddad, unless it’s these Tokyo scientists. They genetically engineered e-coli to let them solve sudoku puzzles.
The puzzle was a 4×4, not quite the 9×9 that we’re used to. An example is shown in the picture. Each number was assigned a colour, so a red colony was the number one, and blue was two. The bacteria had to become the right colour to fit into the sudoku solution.
To solve the puzzle, the bacteria have to know what numbers are around it. For example, the position in the top left has the following data: There is a one in the column, a three in the row and a two in the box. Therefore it needs to be a four.
To become a number four, it needs to receive signals for one, two and three which makes it flip on a switch to say “four.” The switch works only when it receives three different signals.
Signals were transferred between bacteria using phage – viruses that infect bacteria. For example, a number one bacteria would produce a phage which says “Yo, I’m number one.” When that phage infects bacteria around it, they know they are in the presence of a number one. That helps flip the right switch for the bacteria to solve the puzzle.
Hat tip to The Loom.