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Freshwater cyanobacterial blooms limit the utilization of drinking water due to decreased
clarity, bad odor, anoxia in the water column and producing a diverse range of toxins;
hepatotoxins, neurotoxins and cytotoxins. Hepatotoxic microcystin-LR (MC-LR) is the most
intensively studied cyanotoxin and it is the most common type of cyanotoxin. The present study
was based on qualitative and quantitative analysis of cyanotoxin in diverse water bodies in Sri
Lanka and thirty one water bodies in different districts of Sri Lanka were selected for
qualitative and quantitative analysis of microcystin-LR using PCR and ELISA techniques
respectively along with assessment of some other selected physico-chemical water quality
parameters. Presence of MCs producing genes, mcy A, mcy B and mcy E in field samples were
analysed by PCR using specific primers and quantification of Microcystin-LR was done by
Enzyme Link Immuno Sorbent Assay (ELISA) respectively. The results of the present study
relvealed that most of the drinking water reservoirs were having acceptable physico-chemical
parameters for drinking water and MC-LR contamination was ranged between 5.98 ppb to 0.03
ppb. The highest contamination of MC-LR was recorded in Giradurukotte Reservoir (435ppb)
where moderate level of MC-LR was detected in Kurunagala lake (75.6 ppb). PCR results
reveled that most of studied water bodies having MCs producing genes, mcy A, mcy B and
mcy E except Labugama reservoir, Kalatuwawa reservoir, Rathkinda reservoirs, Kantale podi
wewa, Minneriya wewa and Mahaweli river intake. Thus, PCR screening is a cost effective
molecular biological tool to detect cyanotoxin contamination status of a water body in adavance
and it may facilitate to future forcast for actual potential of cyanotoxins production and give an
alarm to take nessaary treatment application for drinking water supply authorities.
