Serratia marcescens had made its self undoubtedly interesting by its strking red pigement of Prodigiosins .This has lead to the craze of the extraction ,purification and characterisition of Prodigiosin.Prodigiosins is charcaterised by its Tri-pyrrole ring .It has a an OR-group on the second ring and a long carbon chain on the third ring.Prodigiosins are considered to be secondary metabolites.Secondary metabolites do not effect important functions such as growth and reproduction but provide a toxicity to surrounding microoragnisms.This activity as well as others allows Prodigiosins to become as useful as it is today .