I could just as easily ask you to show me some groundwater in which not a single microorganism is found. The fact is that our crust is utterly loaded with microorganisms, and everything in it,,,including petroleum will have them. But it almost never means they created the medium in which they are found.
And you do realize,, at some point for your theory to make sense, you have to do more tan find microorganisms in the oil? You have to demonstrate, via provable repeatable chemistry, HOW they do it. You are drawing the exact backwards conclusion.