Characterization of toxin-producing cyanobacteria by using an oligonucleotide probe containing a tandemly repeated heptamer.

Cyanobacteria produce toxins that kill animals. The two main classes of cyanobacterial toxins are cyclic peptides that cause liver damage and alkaloids that block nerve transmission. Many toxin-producing strains from Finnish lakes were brought into axenic culture, and their toxins were characterized. Restriction fragment length polymorphism analysis, probing with a short tandemly repeated DNA sequence found at many locations in the chromosome of Anabaena sp. strain PCC 7120, distinguishes hepatotoxic Anabaena isolates from neurotoxin-producing strains and from Nostoc spp.