Toxins of cyanobacteria

Abstract

Blue-green algae are found in lakes, ponds, rivers and brackish waters throughout the world. In case of excessive growth such as bloom formation, these bacteria can produce inherent toxins in quantities causing toxicity in mammals, including humans. These cyanotoxins include cyclic peptides and alkaloids. Among the cyclic peptides are the microcystins and the nodularins. The alkaloids include anatoxin-a, anatoxin-a(S), cylindrospermopsin, saxitoxins (STXs), aplysiatoxins and lyngbyatoxin. Both biological and chemical methods are used to determine cyanotoxins. Bioassays and biochemical assays are nonspecific, so they can only be used as screening methods. HPLC has some good prospects. For the subsequent detection of these toxins different detectors may be used, ranging from simple UV-spectrometry via fluorescence detection to various types of MS. The main problem in the determination of cyanobacterial toxins is the lack of reference materials of all relevant toxins. In general, toxicity data on cyanotoxins are rather scarce. A majority of toxicity data are known to be of microcystin-LR. For nodularins, data from a few animal studies are available. For the alkaloids, limited toxicity data exist for anatoxin-a, cylindrospermopsin and STX. Risk assessment for acute exposure could be relevant for some types of exposure. Nevertheless, no acute reference doses have formally been derived thus far. For STX(s), many countries have established tolerance levels in bivalves, but these limits were set in view of STX(s) as biotoxins, accumulating in marine shellfish. Official regulations for other cyanotoxins have not been established, although some (provisional) guideline values have been derived for microcystins in drinking water by WHO and several countries.

Massive multiplication of genome and ribosomes in dormant cells (akinetes) of Aphanizomenon ovalisporum (Cyanobacteria)

“…Major blooms have been reported in Australia, Northern Europe, India, New Zealand, South Africa, USA and the Baltic Sea (Carmichael et al, 1990;Codd et al, 1999;Hudnell et al, 2008), indicating a phenomenon of global dimensions. Many Nostocales species produce potent toxins that have been associated with livestock deaths, water quality deterioration and seafood contamination (Codd et al, 2005;Dittmann and Wiegand, 2006;van Apeldoorn et al, 2007). The ability to develop akinetes (spore-like cells) is a survival trait of the Nostocales that provides these toxic species with a competitive advantage over other phytoplankton.…”

Development of a high sensitive automatic setup for screening of microcystins in surface waters by employing a LED-based photometric detector

“…Cyanobacteria thrive in the presence of sunlight and high temperatures, especially in polluted waters that are rich in nutrients [1]. Microcystins are cyanobacterial secondary metabolites delivered in water, which have been characterized as strong hepatotoxins [2][3][4][5][6][7].…”

“…Microcystins are cyanobacterial secondary metabolites delivered in water, which have been characterized as strong hepatotoxins [2][3][4][5][6][7]. The contamination of drinking water by microcystins has been suggested as a risk factor for cancer [1,4,6,7]. Cyanobacterial toxin poisoning in animals has been reported around the world, while human poisoning occurred in Australia after the exposure of individuals to contaminated drinking water [1].…”

“…The contamination of drinking water by microcystins has been suggested as a risk factor for cancer [1,4,6,7]. Cyanobacterial toxin poisoning in animals has been reported around the world, while human poisoning occurred in Australia after the exposure of individuals to contaminated drinking water [1]. Human illness and death associated with microcystin toxicity occurred among dialysis patients during 1996 in Caruaru, Brazil [1,8].…”

“…Human illness and death associated with microcystin toxicity occurred among dialysis patients during 1996 in Caruaru, Brazil [1,8]. These papers showed that there is an awareness concerning the risk that aquatic organism, domestic animals and humans can be poisoned by microcystins delivered in water by the cyanobacteria [1,3,[9][10][11][12][13]. In response, the World Health Organization (WHO) has suggested a provisional guideline value of 1 g L −1 microcystins in drinking water [14].…”