Identification of cyanobacteria and their toxigenicity in environmental samples by rapid molecular analysis

We report molecular analyses which identify cyanobacterial strains present in environmental samples. These analyses do not require the isolation and c ulture of strains. Identification of cyanobacteria used the polymerase chai n reaction (PCR), based on the phycocyanin operon. Differentiation was eith er by restriction endonuclease digestion (restriction fragment length polym orphisms) or sequencing of the PCR products. Identification was based on se quence homology of the intergenic spacer region (IGS) between the beta- and alpha -phycocyanin subunits (PC-IGS) with database records. We have found that the length and sequence of the PC-IGS is capable of predicting the gen us accurately, but not the species. Toxigenicity was determined with oligon ucleotide probes for key steps in the microcystin toxin synthesis pathway. We have shown that it is possible to easily and routinely obtain PCR amplif ication products and differentiate the strains in bloom samples. The method s can detect even minor components in bloom samples, which may not be appar ent on microscopic examination. Genetic probes for microcystin toxigenicity are effective on environmental samples, eliminating the need for isolation and culture of the organisms. The use of a suite of tests described here w ill allow water managers to determine the presence and the type of cyanobac teria and their microcystin toxigenicity. (C) 2001 by John Wiley & Sons, In c.