First let me say I am not a Microbiologist, so I could be totally wrong about all of this.
By "digest, disintegrate, or otherwise liquefy", I think you really mean breaking down a significant amount of the molecular structure of the thing being eaten. How do you wreak havoc on molecules? A few things can do it.
- heat and pressure
PH. You could dissolve the thing being eaten in an acid. What that really means is surrounding the thing being eaten with molecules that are super unstable and eager to give surrounding molecules extra protons. If you surround the thing being eaten by enough of these unstable molecules, the huge surplus of protons will likely cause major damage to the molecules of the thing being eaten.
So in the context of the eating organism, these molecules can almost be thought of as little missiles. But launching these missiles is complicated. The eater organism would have to have evolved a mechanism to safely deliver the molecular payload without itself being dissolved.
Heat and pressure. If you could deliver a large enough burst of energy to the target, you could overcome the molecular bonds and achieve something like disintegration. This definition of disintegration doesn't really fit the notion of The Blob though in my mind, though.
Enzymes. Enzymes are just proteins that tend to catalyze reactions that break down the molecules of the thing being eaten. This is kind of similar to the ph attack method above. I think its worth noting that large complicated enzyme molecules might be an order of magnitude larger than the simple acid molecule imagined above. Enzymes can be specially designed to only affect the molecules of the target. Making the logistics of delivering the attack a little bit easier.
Strong acids are stored in polytetrafluoroethylene in a lab, since they would dissolve glass and most other containers. I kind of like the idea of a bird with a polytetrafluoroethylene beak flying around and spraying its prey with some super strong acid. Is that biologically plausible?... meh... But a flying acid dragon is a wonderful kind of metal \m/