It's pretty laughable that there are people concerned by the ethical ramifications of this. Most of the population eats meat thus contributing to the suffering of animals we have very good reason to believe can feel a form of pain. Our best scientific theories point away from the idea that single-celled organisms feel pain of any sort.
Another example of the strange ethical double-standard scientific researchers must deal with in their research. The general populous is free to commit grossly unethical actions, whereas there is concern scientists are manipulating single-celled organisms. Give me a break .