By-ProductsFormed in the Destruction of Algal Toxins by Oxidants such as Chlorine

ReportNo WSAA 129

October 1997

SYNOPSIS

Previousstudies carried out at the Australian Water Quality Centre showed thatchlorination was effective in oxidising and thus removing acute toxicity ofcyanobacterial peptide hepatotoxins as determined by HPLC and mouse bioassay.Although acute toxicity was removed, it was not known whether the by-productsfrom chlorination of the hepatotoxins were capable of producing subacute toxiceffects. The aim of this project therefore was to determine the by-productsproduced from the chlorination of microcystins and to assess their potentialtoxicity.

Arange of toxin producing and non-toxin producing cultures of Microcystis aeruginosa were chlorinatedto determine the effect on measures of toxicity. The more common disinfectionby-products as well as total halogenated organic components were also measured.Toxicity of the cultures was monitored via specific and non-specific toxicityassays such as the mouse bioassay, HPLC analysis, protein phosphataseinhibition assay and Ames mutagenicity assay in order to determine any trendbetween acute or subacute toxicity and chlorination of the toxin producing Microcystis cultures.

Proteinphosphatase inhibition decreased after chlorination in strains of Microcystis which produced toxin. Thiswas consistent with the elimination of acute toxicity in mice and HPLC analysisresults. No correlation could be made between the results of Ames mutagenicitytesting and the presence of microcystins. There was also no recognisable trendbetween any of the toxicity assay results and the presence of chlorinateddisinfection by-products. It was found that chlorination of the various Microcystis cultures yielded similarchlorinated by-products. However different ratios of these compounds were foundwhich implies the presence of different organohalogen precursors in somestrains.

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