The cyanobacterium Anabaena sp. strain ATCC 27898 was found to utilize the siderophore schizokinen to accumulate iron from the environment. This organism had previously been shown to produce schizokinen under low-iron conditions, and we observed that the iron-transport capability is also increased in response to iron limitation. Uptake activity was specific for ferric schizokinen displayed kine...

The cyanobacteria are an ancient and diverse group of prokaryotes capable of oxygenic photosynthesis and plasmids have been found in both unicellular and filamentous types. Currently, all plasmids are cryptic and only one plasmid, pUH24, from a unicellular non-nitrogen-fixing cyanobacterium, has been sequenced (1). Comparative searches (TFASTA, FASTA (2)) of pUH24 sequences did not show similar...

Experiments were conducted to determine the influence of Chlamydomonas sp. on nitrogen fixation (C(2)H(2) --> C(2)H(4)) in Azolla filiculoides and on the nitrogen fixation and growth of free-living Anabaena azollae 2B organisms. Inoculation of azolla medium with Chlamydomonas sp. was associated with decreased nitrogenase activity in A. filiculoides and with increases in the density of a fungal ...