Toxigenicity of {\it Aphanizomenon flos-aquae\/}, {\it Alexandrium tamarense\/} and associated organisms
Abstract
Paralytic shellfish poisoning (PSP) toxins are produced by a number of taxonomically unrelated organisms such as the marine dinoflagellate Alexandrium tamarense and the fresh-water cyanobacterium Aphanizomenon flos-aquae. The identity of a common vector responsible for the production of PSP toxins was investigated using two approaches. The first approach examined bacteria associated with A. tamarense, mackerel (Scomber scombrus Linn.), and arrowworm (Sagitta elegans Verill) for their role in PSP toxin production. The second approach examined the possibility that plasmid DNA may act as the transferrable vector, common only to the toxigenic organisms. Toxigenic and non-toxigenic A. flos-aquae were therefore examined for plasmid DNA. The primary method for the detection of toxins in isolated bacteria was a neuroblastoma tissue culture assay method (Kogure et al., 1988) modified for this investigation.^ Forty bacteria were isolated from A. tamarense, of which one marine bacterium displayed saxitoxin-like activity in the bioassays used and was cultured for the isolation of toxin. Processing of 6.5 liters of culture broth yielded 140 mouse units of toxin after CG-50 Na$\sp+$ ion exchange chromatography and gel filtration with Bio-gel P-2. Further purification yielded 25 MU, but the identity of the toxin as a known PSP toxin could not be confirmed by HPLC. Bacteria isolated from the viscera of locally obtained mackerel and from arrowworms found in Narragansett Bay also displayed PSP-type activity.^ Different rapid extraction methods and CsCl equilibrium centrifugation did not reveal the presence of plasmid DNA. The purified DNA was degraded by exonuclease III. Restriction enzyme analysis of the chromosomal DNAs from non-toxic and the toxic Aphanizomenon flos-aquae revealed no differences.^ The tissue culture method for the assay of PSP toxins was modified by the use of the tetrazolium salts MTT and XTT to determine cell viability and toxin concentration. The method could detect at least 0.2 ng $\pm$ 0.02 ng saxitoxin. ^
Subject Area
Health Sciences, Toxicology|Biology, Microbiology|Biology, Oceanography|Environmental Sciences|Agriculture, Fisheries and Aquaculture
Recommended Citation
Claudia Patricia Koerting-Walker,
"Toxigenicity of {\it Aphanizomenon flos-aquae\/}, {\it Alexandrium tamarense\/} and associated organisms"
(1990).
Dissertations and Master's Theses (Campus Access).
Paper AAI9120424.
http://digitalcommons.uri.edu/dissertations/AAI9120424