The lambda bacteriophage, a virus that infects bacteria, was discovered by Esther Miriam Zimmer Lederberg. And this led to the discovery of the fertility factor, which she named the F factor.

She and her husband, Joshua Lederberg, developed a method for bacteria replica planting, enabling to picked up bacteria colonies from a petri dish and successfully placed them into another (Lederberg method). While both are credited for this method, only her husband received the Nobel Prize in Physiology or Medicine 1958 "for his discoveries concerning genetic recombination and the organization of the genetic material of bacteria".