[Production of the antibiotic-algicide cyanobacterin LU-2 by a filamentous cyanobacterium Nostoc sp]

A strain of cyanobacterium of Nostoc has been isolated, and found to produce a new antibiotic cyanobacterin LU-2. The antibiotic is synthesized by the cyanobnacterium under intensive cultivation conditions in a liquid mineral medium. Cyanobacterin LU-2 is an exometabolite; its maximum accumulation in the medium is achieved at 34 degrees. Cyanobacterin LU-2 is active against many cyanobacteria tested, including those of Microcystis and Aphanizomenon which are principals to give rise to blooms in fresh water supplies. It is poorly active against green algae and inactive against fungi and bacteria. The antibiotic hinders cell division in Synechococcus sp. R-2 (PCC 7942). It causes compression of the cytoplasm and exfoliation of the cell contents from cell wall; the distance between tylacoids is increased and their destruction is observed. The antibiotic hinders markedly light-dependent oxygen evolution. Cyanobacterin LU-2 is substance of a phenolic nature containing amino-sugar.