Specifically, an organism has to store latent information that’s unobservable to anything it interacts with (i.e., its ecosystem)—or at least, anything with an interest in predicting and controlling it. Otherwise, it has no possibility of independent behavior, and it’s effectively part of a colony organism (or an organ of another organism). It also has no differential behavior for natural selection to act on, so it can’t evolve in a Darwinian sense.

To take your example of bacteria, we don’t know and control the entirety of each individual bacterium’s behavior, but it has happened: it’s how mitochondria ceased to be independent organisms.