The Smithsonian has an interesting article on Alexander Fleming, the man who discovered penicillin, revealing how the scientist used his bacterial cultures to paint works of art. Fleming used different bacterial strains to create a range of colours, timing his innoculations so that the different species would mature at the same time.
From the OP:
It is not clear why Fleming started painting microbes; perhaps he picked up a brush one day and noticed that it felt like the loop he used for his bacteria. Or maybe it was due to the promiscuous sexual predilections of artists. Fleming worked at St. Mary's hospital in London, where he treated syphilis cases. Many of his patients were painters, and those painters sometimes gave Fleming paintings and perhaps even lessons in return for treatment. Fleming's palette grew richer with time as he found bacteria with the colors he needed. He found joy in discovering a strange new strain of bacteria, in the way that a field biologist might feel the same in happening upon some new and wondrous bird. He collected unusual life forms in the hope that one of them might someday prove useful.