Complex sentence: The term "autoinduction" was first coined in 1970, when it was observed that the bioluminescent marine bacterium "Vibrio fischeri" produced a luminescent enzyme (luciferase) only when cultures had reached a threshold population density.
Split into simpler sentences: The term "autoinduction" was first coined in 1970. It was observed that the bioluminescent marine bacterium "Vibrio fischeri" produced a luminescent enzyme (luciferase) only when cultures had reached a threshold population density.