Phylogenetic diversity of bacteria associated with toxic and non-toxic strains of Alexandrium minutum

Abstract

Marine planktonic dinoflagellates are usually associated with bacteria, some of which seem to have a symbiotic relation with the dinoflagellate cells. The role of bacteria in dinoflagellate life cycles is not well known and their influence on toxin production is controversial. The potential relationship between dinoflagellate-associated bacteria and toxin production was experimentally investigated by identifying and comparing bacterial populations present in toxic (AL1V) and non-toxic (AL4V) strains of Alexandrium minutum. Part of the 16S rDNA of the bacteria associated with these clones was PCR amplified, cloned and sequenced, in order to identify the bacterial species present in each culture. Results indicated that most of the bacteria species were present in the cultures of both A. minutum clones, but some were specific to either the toxic or the non-toxic clone. Some,
but not all bacteria identified were also isolated, and appropriate conditions for their culture were developed as a first step in assessing their role in the growth and toxin production by A. minutum.