What organisms can vegans work with?

I've been thinking about this, and it would seem that the only organisms that vegans can work with in biology in terms of not using any animal products would be photosynthetic or saphrotrophic organisms, maybe. I guess vegans could work in paleontology, but I think dead organisms would be an obvious exception.

Let me back up. Obviously vegans should not work with animals because poking, prodding, and killing animals wouldn't fit with their aim of not harming animals. Even observers of animal behaviour would inevitably have to harm animals in some fashion, I think. They cannot work with cell culture because cell culture requires animal products like fetal bovine serum (fetal calf serum, what's the difference anyway?) and bovine serum albumin. They cannot work with yeast or bacteria because a lot of growth media requires protein sources like hydrolysed milk casein. Ditto with most other branches of life, because ultimately I'd think one would have to use animal products somewhere in there. Even plants might be tricky especially since molecular biology has its fingers in practically every field of experimental biology including botany-- for instance, cloning plant DNA would inevitably require bacteria. Unless a vegan were content to spend their scientific career describing plants or other organisms in the most superficial way without molecular biology, then I think there really is no career in experimental biology for vegans.

I would love it if a vegan could confirm this, or otherwise correct any misconception of mine about the vegan lifestyle. Anyway, that's my small thought of the day.