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Aquatic Microbial Ecology

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AME 29:1-9 (2002)  -  doi:10.3354/ame029001

Sodium channel blocking (SCB) activity and transformation of paralytic shellfish toxins (PST) by dinoflagellate-associated bacteria

Elizabeth A. Smith*, Fiona H. Mackintosh, Faye Grant, Susan Gallacher

Fisheries Research Services, Marine Laboratory, PO Box 101, Victoria Road, Aberdeen AB11 9DB, Scotland, UK

ABSTRACT: Bacteria associated with toxic algae in culture have been implicated in the enhancement of algal toxin production and in auto-toxigenesis, with taxon specificity of the bacteria suggested to be important in their association with the algae. In this study, bacteria isolated from toxic and non-toxic dinoflagellates have been examined for both their potential to produce sodium channel blocking (SCB) toxins, as ascertained by the mouse neuroblastoma assay, and their ability to biotransform paralytic shellfish toxins (PST) using high-performance liquid chromatography (HPLC). Toxigenic bacteria were found to belong to the a- and γ-Proteobacteria. Bacteria capable of SCB activity were present in PST-producing Alexandrium tamarense and A. lusitanicum cultures, while the bacterial flora isolated from a non-toxic A. tamarense strain did not appear to demonstrate this trait. A disparate population of the bacterial flora associated with non-PST-producing Scrippsiella trochoidea also demonstrated SCB activity. Some bacteria from all the dinoflagellates examined were capable of transforming PST, with possible mechanisms including oxidase activity with transformation of gonyautoxins GTX 2/3 to GTX 1/4, reductive elimination as demonstrated by the transformation of GTX 1/4 to GTX 2/3, and further unknown pathways. Noticeably, there was little overlap between bacteria demonstrating SCB activity and those that were able to modify PST, indicating that biosynthesis of SCB toxins and catabolism of PST may not be related in these bacterial isolates.

KEY WORDS: Dinoflagellates · Bacteria · Sodium channel blocking toxins · Mouse neuroblastoma assay · Paralytic shellfish toxins · HPLC · Biotransformations

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