[alex_duf]

The reason I ask is that it seems subsequences of DNA are enough to generate proteins, or other molecules. (am I right? if not anyone who knows biology please correct me)

It doesn't have to be the whole code that's dangerous, what about a section of it?

That still makes it very improbable, but orders of magnitude more than the whole sequence.

[waserwill]

The encoding used by these sorts of projects avoids 'ATG' (start site), and possibly the Shine-Dalgarno Sequence (where ribosomes attach), if they do it right. The bacterial DNA can mutate, but the likelihood of that mutation creating a viable protein, let alone a dangerous one, is very low. Honestly, since these stored data aren't coding, the chances of them surviving for long, even in a population of bacteria, is low. Bacteria tend to favor smaller genomes, with higher percentage of coding DNA.