Species-specific polyamines from diatoms control silica morphology

Biomineralizing organisms use organic molecules to generate species-specifi c mineral patterns. Here, we describe the chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic cons tituent of diatom biosilica. These substances are the longest polyamine cha ins found in nature and induce rapid silica precipitation from a silicic ac id solution. Each diatom is equipped with a species-specific set of polyami nes and silica-precipitating proteins, which are termed silaffins. Differen t morphologies of precipitating silica can be generated by polyamines of di fferent chain lengths as well as by a synergistic action of long-chain poly amines and silaffins.