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 generaAnabaena,Cylindrospermopsis, andAphanizomenon. 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 byAphanizomenon flos-aquae, the only known CYN producer in Germany. Therefore, we attempted to identify PSP toxin, ATX, and CYN producers by isolating and characterizing 92Anabaena, Aphanizomenon, andAnabaenopsisstrains 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, 14Aphanizomenon gracilestrains 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. ThesxtAgene, which is part of the saxitoxin gene cluster, was found in the 14 PSP toxin-producingA. gracilestrains and in 11 non-PSP toxin-producingAphanizomenon issatschenkoi,A. flos-aquae,Anabaena planktonica, andAnabaenopsis elenkiniistrains. ATX and CYN were not detected in any of the isolated strains. This study is the first confirming the role ofA. gracileas a PSP toxin producer in German water bodies.

For decades frequent mass mortalities of Lesser Flamingos (Phoeniconaias minor Geoffroy) have been observed at alkaline-saline Kenyan Rift Valley lakes. To estimate the potential influence of toxic cyanobacteria on these mass deaths, the phytoplankton communities were investigated in Lakes Bogoria, Nakuru and Elmenteita. Cyanobacterial toxins were analyzed both in the phytoplankton from the three lakes and in isolated monocyanobacterial strains of Arthrospira fusiformis, Anabaenopsis abijatae, Spirulina subsalsa and Phormidium terebriformis. Lake Bogoria was dominated by the cyanobacterium A. fusiformis. In L. Nakuru and L. Elmenteita the phytoplankton mainly consisted of A. fusiformis, A. abijatae and Anabaenopsis arnoldii, and in L. Nakuru an unknown Anabaena sp. was also found. Furthermore, this is the first time A. abijatae and the unknown Anabaena sp. have been found in Kenyan lakes. Phytoplankton wet weight biomass was found to be high, reaching 777 mg L⁻¹ in L. Bogoria, 104 mg L⁻¹ in L. Nakuru and 202 mg L⁻¹ in L. Elmenteita. Using HPLC, the cyanobacterial hepatotoxins microcystin-LR, -RR -YR, -LF and -LA and the neurotoxin anatoxin-a were detected in phytoplankton samples from L. Bogoria and L. Nakuru. Total microcystin concentrations amounted to 155 μg microcystin-LR equivalents g⁻¹ DW in L. Bogoria, and 4593 μg microcystin-LR equivalents g⁻¹ DW in L. Nakuru, with anatoxin-a concentrations at 9 μg g⁻¹ DW in L. Bogoria and 223 μg g⁻¹ DW in L. Nakuru. In L. Elmenteita phytoplankton, no cyanobacterial toxins were found. A. fusiformis was identified as one source of the toxins. The isolated strain of A. fusiformis from L. Bogoria was found to produce both microcystin-YR (15.0 μg g⁻¹ DW) and anatoxin-a (10.4 μg g⁻¹ DW), whilst the A. fusiformis strain from L. Nakuru was found to produce anatoxin-a (0.14 μg g⁻¹ DW). Since A. fusiformis mass developments are characteristic of alkaline-saline lakes, health risks to wildlife, especially the Arthrospira-consuming Lesser Flamingo, may be expected.