Seasonal variations in microcystin contents of danish cyanobacteria

Abstract

One hundred ninety-eight of 296 phytoplankton net samples, collected from Danish fresh waters during 1993-1995, contained microcystins when analyzed by high-performance liquid chromatography (HPLC), and the seasonal variations in microcystin contents were examined.

Diversity of hepatotoxic microcystins and bioactive anabaenopeptins in cyanobacterial blooms from Greek freshwaters

“…The microcystin concentrations in Greece are comparable to the data reported from other countries, for example, Japan (25-2026 g g À1 ; Park et al, 1993b), South Korea (19-1489 g g À1 ; Park, 2001), and Poland (23-1687 g g À1 ; Jurczak et al, 2004). Higher microcystin concentrations have been reported for China (210-7280 g g À1 ; Zhang et al, 1991), Portugal (1000-7100 g g À1 ; Vasconcelos, 1996), and Germany (11-5595 g g À1 ; Fastner et al, 1999b) and lower concentrations in some samples from Denmark (11-737 g g À1 ; Henriksen and Moestrup, 1997) and Canada (4-605 g g À1 ; Kotak et al, 1993). A comparison of the TMCs of different countries indicated some differences in absolute concentrations, as Chorus (2001) also has pointed out.…”

“…The percentage of microcystin-containing samples as determined by HPLC (100%) found in this study is the highest reported in the literature (for a review see Sivonen and Jones, 1999). Similar percentages have been reported for Portugal (Vasconcelos et al, 1996) and Japan (Watanabe et al, 1992;Park et al, 1993b), whereas the usual percentage has been found to be lower in countries such as France (73%; Vezie et al, 1997), Germany (72%; Fastner et al, 1999b), and Denmark (67%; Henriksen and Moestrup, 1997) or even lower, for example, in the United Kingdom (56%; Ward et al, 1997) and China (50%; Zhang et al, 1991). Anabaenopeptins A and B co-occurred with microcystins in 27% of the samples collected from Lakes Kastoria, Pamvotis, and Zazari.…”

“…The most commonly occurring genus in these bloom samples was Microcystis. Demethylated microcystins have been found in blooms containing Planktothrix and Anabaena in addition to Microcystis, in Finland Luukkainen et al, 1994), Denmark (Henriksen, 1996;Henriksen and Moestrup, 1997), and Germany (Fastner et al, 1999b). In Greece demethylated microcystins were not common and never exceeded 8% of the TMC.…”

Pressurized liquid extraction of toxins from cyanobacterial cells

“…Additional experiments mainly investigated methanol and binary mixtures. Extraction of MCYST has been achieved using 100% methanol (Henriksen and Moestrup, 1997), methanol-water solutions (Zweigenbaum et al, 2000;Hummert et al, 2000), methanoln-butanol-water (Lawton et al, 1994;Namikoshi et al, 1998;Brittain et al, 2000;Park et al, 2001), 5% acetic acid solutions (Lawton et al, 1994), and supercritical fluid CO 2 modified with acetic acid (Pyo et al, 1999). Ramanan et al (2000) assessed extraction efficiency of MCYST-LR and MCYST-LA with different solvents and found that the extraction of MCYST-LR was more efficient when 75% (v/v) methanol in water (MeOH) was used.…”