Identification of cyanobacterial producers of shellfish paralytic toxins in lake Baikal and reservoirs of the Angara River

Extensive Contamination of Water with Saxitoxin Near the Dam of the Irkutsk Hydropower Station Reservoir (East Siberia, Russia)

“…The reported concentration of saxitoxin and its analogues in fresh water bodies varies over a wide range. For example, concentrations of 1.93 ± 0.64 μg L −1 of saxitoxin (measured by ELISA) have been reported for the coastal zone of Lake Baikal [ 10 ], while a particular site in a Finnish lake was found to contain 1070 μg L −1 saxitoxin [ 24 ]. Children who swam in the latter showed symptoms of poisoning, although these were different from those which would be caused by saxitoxin [ 24 ].…”

“…D. lemmermannii had already been found in Lake Baikal and the Irkutsk Reservoir earlier [ 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. It was identified as a dominating cyanobacteria in the plankton of Lake Baikal, sometimes producing large floating masses a few kilometers long [ 8 , 9 ].…”

“…It was recently demonstrated that D. lemmermannii samples collected in and around Lake Baikal contain the sxtA gene involved in the synthesis of saxitoxins. STXs were detected by the immunoassay approach (ELISA) in D. lemmermannii in Baikal water within patches of the blooming cyanobacteria, although in small concentrations [ 10 , 11 ]. After we developed a new method of determination of STX based on precolumn derivatization with 2,4-dinitrophenylhydrazine followed by HPLC-ESI-MS, and for the first time applied it to analysis of polluted water as described in the present paper, we found that the concentration of STX in the patch of discolored water leaning against the dam of the Irkutsk hydroelectric power plant was extremely high, up to 600 μg L −1 , a few hundred times higher than the health alert level (3 μg L −1 ) adopted for drinking water in some countries [ 12 , 15 ].…”

“…Primers for sxtA were used to carry out a polymerase chain reaction (PCR). Amplification of the sxtA gene fragment has been used in published studies for the identification of various saxitoxin-producing cyanobacteria in fresh waters [ 21 ], including Lake Baikal [ 8 , 10 ]. Extracted DNA of the cyanobacteria Aphanizomenon gracile was taken as a positive control [ 11 , 16 ], and DNA of Synechococcus Bal 9710 was used as a negative control as this species does not contain the sxtA gene.…”

“…D. lemmermannii found in freshwater can produce a neuroparalytic toxin—saxitoxin and its analogues. This hazardous toxin was found recently in the biomass of D. lemmermannii inhabiting Lake Baikal, as well as in the water of the lake, but its concentration semi-quantitatively determined by immunoassay analysis (ELISA) was small [ 10 , 11 ], mostly under 3 μg L −1 , the value which is a health alert level for drinking water in a few countries [ 12 ]. To perform quantitative analysis, we developed a new method for saxitoxin determination in water based on HPLC-MS with precolumn modification of saxitoxin with 2,4-dinitrophenylhydrazine.…”