Cyanophycin, or multi-L-arginyl-poly (L-aspartic acid), is a non-protein, non-ribosomally produced amino acid polymer composed of an aspartic acid backbone and arginine side groups. Cyanophycin was first detected in 1887 by the Italian botanist Antonino Borzì and can be found in most cyanobacteria and a few heterotrophic bacteria such as Acinetobacter sp. Cyanophycin is largely insoluble under physiological conditions and is accumulated in the form of granules in the cytoplasm during phosphate or sulfur starvation, generally in the early and mid-stationary phase. It is used as a nitrogen- and possibly carbon-storage compound and also serves as a dynamic buffer for fixed nitrogen in cyanobacterial heterocysts. Nitrogen and carbon are mobilized from cyanophycin by intracellular cyanophycinas