Paralytic Shellfish Poisoning Toxin-Producing CyanobacteriumAphanizomenon gracilein Northeast Germany

Abstract

Neurotoxic paralytic shellfish poisoning (PSP) toxins, anatoxin-a (ATX), and hepatotoxic cylindrospermopsin (CYN) have been detected in several lakes in northeast Germany during the last 2 decades. They are produced worldwide by members of the nostocalean genera Anabaena, Cylindrospermopsis, and Aphanizomenon. Although no additional sources of PSP toxins and ATX have been identified in German water bodies to date, the observed CYN concentrations cannot be produced solely by Aphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92 Anabaena, Aphanizomenon, and Anabaenopsis strains from five lakes in northeast Germany. In a polyphasic approach, all strains were morphologically and phylogenetically classified and then tested for PSP toxins, ATX, and CYN by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA) and screened for the presence of PSP toxin-and CYN-encoding gene fragments. As demonstrated by ELISA and LC-MS, 14 Aphanizomenon gracile strains from Lakes Melang and Scharmützel produced four PSP toxin variants (gonyautoxin 5 [GTX5], decarbamoylsaxitoxin [dcSTX], saxitoxin [STX], and neosaxitoxin [NEO]). GTX5 was the most prevalent PSP toxin variant among the seven strains from Lake Scharmützel, and NEO was the most prevalent among the seven strains from Lake Melang. The sxtA gene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producing A. gracile strains and in 11 non-PSP toxin-producing Aphanizomenon issatschenkoi, A. flos-aquae, Anabaena planktonica, and Anabaenopsis elenkinii strains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role of A. gracile as a PSP toxin producer in German water bodies.

First report of cyanobacterial paralytic shellfish toxin biosynthesis genes and paralytic shellfish toxin production in Polish freshwater lakes

“…Additionally, active but lowlevel biosynthesis of PSTs was demonstrated by the presence of saxitoxin or decarbamoylsaxitoxin in 19% of the 68 samples tested. The results are in line with other studies investigating central European freshwaters (Ballot et al, 2010;Ledreux et al, 2010, Jančula et al, 2014.…”

“…Since then, toxinspecific molecular genetic analysis has been employed in the study of PST-producing cyanobacteria in culture and in the field. Several studies on European cyanobacteria have been carried out on strains isolated from freshwater lakes and reservoirs, and many have targeted the PST biosynthesis gene sxtA showing that while all PST-producing strains do carry the gene, it can also be found in Anabaena, Anabaenopsis and Aphanizomenon strains which appear to lack the ability to produce the toxins (Ballot et al, 2010;Ledreux et al, 2010;Cires et al, 2014). Other sxt genes, including sxtG, sxtB, sxtI and sxtX, have been studied to a lesser extent , Gkelis and Zaoutsos, 2014, Savela et al, 2015.…”

Bismuth oxybromide promoted detoxification of cylindrospermopsin under UV and visible light illumination

“…Cylindrospermopsin (CYN) is one of the common members of cyanotoxins which always cause human injury. CYN originates from several cyanobacteria, such as Cylindrospermopsis raciborskii [3], Umezakia natans [4], Aphanizomenon ovalisporum [5], Anabaena bergii [6], Raphidiopsis curvata [7], Aphanizomenon flos-aquae [8], Anabaena lapponica [9], Lyngbya wollei [10] and Aphanizomenon gracile [11]. CYN has neurotoxic effects (inhibition of protein synthesis by binding to liver DNA and forms single DNA adducts which results in liver damage), hepatotoxic effects (inhibition of glutathione synthesis in hepatocytes), and cytotoxic effects (inhibitor of cytochrome P450) [12].…”

On the occurrence and toxicity of Cylindrospermopsis raciborskii in Poland

“…The presence of STX was reported in a bloom dominated by C. raciborskii in Greece but convincing evidence is insufficient due to a lack of molecular and analytical studies conducted on the isolated strain (Gkelis and Zaoutsos 2014). Nevertheless, other nostocalean cyanobacteria are known to be responsible for STX production (Ballot et al 2010;Cirés et al 2014). STXs are neurotoxic alkaloids that block voltage-gated sodium channels in neuronal cells, also implicated in paralytic shellfish poisoning (O'Neill et al 2016).…”