Common bacterial symbionts in clonal cultures of the toxic dinoflagellate Ostreopsis lenticularis

The marine toxic dinoflagellate Ostreopsis lenticularis Fukuyo 1981 is implicated as the major vector in ciguatera fish poisoning in the southwest coast of Puerto Rico. Studies have demonstrated that bacteria play a role in the production of ciguatoxin by the dinoflagellate and that different clonal cultures of Ostreopsis harbor different culturable bacterial symbionts. It was recently demonstrated the presence of viable but non culturable (VBNC) species of bacteria associated with O. lenticularis. More than 100 associated bacteria from two toxic clonal cultures of Ostreopsis (#302, and #303), were examined for common bacterial strains that could be involved in the production of ciguatoxins. DNA extraction, PCR amplification of partial small subunit ribosomal DNA (rDNA), denaturing gradient gel electrophoresis (DGGE) and DNA sequencing were performed. One uncultured bacterium belonging to the genus Cytophaga was found to be common to both clones, indicating a close association with the dinoflagellate and its possible involvement in the ciguatoxin production.