Absence of the nitrogen reserve polymer cyanophycin from marineSynechococcusspecies

Cyanophycin is a high molecular weight co-polymer of aspartate and arginine, hitherto considered characteristic of all cyanobacteria. Chemical analysis and radioisotopic incorporation procedures have shown that precipitable cyanophycin is absent from the five species of Synechococcus tested, including the marine Synechococcus WH7803 (type DC2). The implications with respect to the role of cyanobacterial nitrogen reserves are discussed.