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Identification and Characterization of Potentially Algal‐lytic Marine Bacteria Strongly Associated with the Toxic Dinoflagellate Alexandrium catenella
Author(s) -
AMARO ANA M.,
FUENTES MARÍA S.,
OGALDE SANDRA R.,
VENEGAS JUAN A.,
SUÁREZISLA BENJAMÍN A.
Publication year - 2005
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.2005.00031.x
Subject(s) - biology , dinoflagellate , microbiology and biotechnology , bacteria , algal bloom , marine bacteriophage , 16s ribosomal rna , botany , phytoplankton , ecology , nutrient , genetics
. The toxic dinoflagellate Alexandrium catenella isolated from fjords in Southern Chile produces several analogues of saxitoxin and has been associated with outbreaks of paralytic shellfish poisoning. Three bacterial strains, which remained in close association with this dinoflagellate in culture, were isolated by inoculating the dinoflagellate onto marine agar. The phenotypically different cultivable bacterial colonies were purified. Their genetic identification was done by polymerase chain reaction amplification of the 16S rRNA genes. Partial sequence analysis suggested that the most probable affiliations were to two bacterial phyla: Proteobacteria and the Cytophaga group. The molecular identification was complemented by morphological data and biochemical profiling. The three bacterial species, when grown separately from phytoplankton cells in high‐nutrient media, released algal‐lytic compounds together with aminopeptidase, lipase, glucosaminidase, and alkaline phosphatase. When the same bacteria, free of organic nutrients, were added back to the algal culture they displayed no detrimental effects on the dinoflagellate cells and recovered their symbiotic characteristics. This observation is consistent with phylogenetic analysis that reveals that these bacteria correspond to species distinct from other bacterial strains previously classified as algicidal bacteria. Thus, bacterial‐derived lytic activities are expressed only in the presence of high‐nutrient culture media and it is likely that in situ environmental conditions may modulate their expression.