ToxicCyanobacteria in Water Supplies: Analytical Techniques

ReportNo WSAA 26

May 1991




Thisproject, jointly funded by the Urban Water Research Association of Australiaand the South Australian Engineering and Water Supply Department, was undertakenfor the purpose of identifying toxic algae present in water supplies anddetermining their public health significance. Five discrete aims wereidentified, viz,


(1)    To developmethods for the quantitative determination of toxins produced by algae


(2)    To developmethods for the identification of toxic strains of algae


(3)    To investigateconditions which promote toxin production


(4)    To determine thespatial and temporal distribution of toxins in algal blooms


(5)    To assess thepublic health significance of toxin production


Theprincipal findings of the research carried out are:


Peptidehepatotoxins can be readily separated in extracts of scum samples by highperformance liquid chromatography (HPLC) using isocratic elution with anacetonitrile/ phosphate buffer mobile phase and UV detection at 240 nm. Thesetoxins are readily extracted using butanol/ methanol/ water with highprecision.


Toxinscan be isolated using preparative HPLC and in most cases identified using fastatom bombardment (FAB) mass spectrometry.


Microcystinswere identified in scum samples from a number of geographically separatedlocations. Although concentrations varied considerably at some locations overtime, the same compounds were always present. At other locations differentmicrocystins were present at different times. Because of the manner of samplingit is not known whether these findings were due to spatial variation within thebloom, to temporal variation or to a combination of both.


·        Nodularin was identified in toxic samples of Nodularia spumigena from Lake Alexandrina, SA.


·        There are a number of microcystins formed by Australian species of Microcystis aeruginosa with up to sixpossibly occurring in any one sample.


·        Samples which are “non-toxic” by mouse bioassay may still contain lowlevels of microcystins.


Withinthe time available it was not possible to address all aims fully. Inparticular, methods for identifying toxic strains of algae were notinvestigated. It was intended to develop allozyme electrophoresis as a methodfor identifying toxic strains and compare results with conventionalmorphological taxonomy. In addition, only limited investigations of conditionsaffecting toxin production, and of the spatial and temporal distribution oftoxins in blooms were carried out. The results of these investigations will bepresented in a separate UWRAA report at a later date. Finally the overallfindings of the investigation were inadequate to allow the issue of the publichealth significance of toxins to be addressed. The investigation also centredon the peptide toxins produced by cyanobacteria. Neurotoxins produced by othercyanobacteria, especially species of Anabaena,were not studied.


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