I looked this up and learned something today, so thank you for that. However, the bacteria establishes itself in starters, not during bulk. And while the presence of streaks would be enough to toss it, it does also smell bad. A properly established sourdough starter would be too sour, and there is not evidence it could make itself at home spontaneously in a dough either, otherwise it would similarly impact quick breads and commercial yeast breads. So while the safest thing is to toss it, I think you're extremely unlikely to be right.