Finding a Way to Construct a Computer from Multiplying Bacteria

This comes from a boy in Germany, when I asked him what we wants to create: "It appears to be possible to construct a computer based entirely on bacterial processes. What that would require, is probabilistic emulation and self-assembly of logical gates. Using the similar self-assembly principles those used for constructing nanobots, it could probably be possible to construct a computer that grows in cellular medium."

Any specific ideas how to do that, and do that safely, are welcome here.