Hepatotoxin (microcystin) and neurotoxin (anatoxin‐a) contained in natural blooms and strains of cyanobacteria from Japanese freshwaters

Abstract

Amounts of hepatotoxic microcystin and neurotoxic anatoxin-a were estimated in natural blooms and strains of cyanobacteria from freshwaters in Japan. A simultaneous analysis method of anatoxin-a and microcystin was applied to natural bloom samples, which has been dominated by several species and the strains of cyanobacteria which produced simultaneously both toxins. The natural blooms examined in the present study were mainly composed of Anabaena and Oscillatoria, but most also contained Microcystis and other cyanobacteria. Only one sample was almost unialgal, Anabaena spiroides, collected from Lake Sagami. The toxins in 14 samples collected from nine different natural blooms during 1988-1992 were identified as microcystins-RR, -YR, and -LR; desmethyl-7-microcystin-LR (7-DMLR); and anatoxin-a. Microcystins were the main toxins contained in these natural blooms, with anatoxin-a not being detected or of very little quantity. 7-DMLR was detected in samples only from Lake Kasumigaura. Five strains of Anabaena isolated from waters in Japan produced a small amount of anatoxin-a, but no microcystins. One half of the strains of Microcystis produced microcystins and/or anatoxin-a. This is the first study showing Microcystis producing both anatoxin-a and microcystins.

Cyanobacteria and microcystins occurrence in the Guadiana River (SW Spain)

“…were the dominant species throughout the monitoring period. These results are in accordance with data found from other authors [4,[43][44][45][46], who had also shown that M. aeruginosa and Oscillatoria spp. were the predominant species in freshwater reservoirs throughout the world.…”

Application of Real-Time PCR for Quantification of Microcystin Genotypes in a Population of the Toxic CyanobacteriumMicrocystissp

“…However, only the largest colonies of Microcystis (Ͼ100 m) were sampled individually in the study of Kurmayer et al (14), and it has also been found that the larger colonies (Ͼ340 m) had the highest mcyB proportion but contributed the smallest fraction to the total cell number, Ͻ10% (15). On the other hand, Microcystis populations have been found to vary in hepatotoxicity within a few weeks, e.g., in 50% lethal dose (expressed in milligrams [dry weight] per kilogram of body weight) (7) or in microcystin concentration (12,21), and a mosaic structure for toxic cyanobacterial blooms has been suggested (4,22,30). In the present study, with one exception, short-term variation ranged from 1 to 38%, and the data on mcyB genotype proportions showed maxima on a weekly or biweekly scale (Fig.…”

Guidance values for microcystins in water and cyanobacterial supplement products (blue-green algal supplements): a reasonable or misguided approach?

“…In addition, the overall toxicity of a bloom cannot be defined because of variations in toxin concentration temporally and spatially within a water body experiencing the bloom. There may be also large year-to-year fluctuations in the levels of cyanobacteria and their toxins (Hoeger, 2003;Hoeger et al, 2004b;Park et al, 1993) and seasonal variations with regard to the dominant species of toxic cyanobacteria and hence, the toxins present (Henriksen and Moestrup, 1997;Hoeger et al, 2004b;Xu et al, 2000). III.…”