A morphological and phylogenetic study of a filamentous cyanobacterium, Microcoleus vaginatus, associated with the moss Mnium cuspidatum

Cyanotoxins associated with macrophytes in Berlin (Germany) water bodies - Occurrence and risk assessment

Fatal dog poisoning after uptake of neurotoxic cyanobacteria associated with aquatic macrophytes in Tegeler See (Berlin, Germany) raised concerns about critical exposure of humans, especially children, to cyanotoxins produced by macrophyte associated cyanobacteria during recreational activity. From 2017 to 2021 a total of 398 samples of macrophytes washed ashore at bathing sites located at 19 Berlin lakes were analysed for anatoxins, microcystins, and cylindrospermopsins, as were 463 water samples taken in direct proximity to macrophyte accumulations. Cyanotoxins were detected in 66 % of macrophyte samples and 50 % of water samples, with anatoxins being the most frequently detected toxin group in macrophyte samples (58 %) and cylindrospermopsins in water samples (41 %). Microcoleus sp. associated with the water moss Fontinalis antipyretica was identified as anatoxin producing cyanobacterium in isolated strains as well as in field samples from Tegeler See. Anatoxin contents in macrophyte samples rarely exceeded 1 μg/g macrophyte fresh weight and peaked at 9. 2 μg/g f.w. Based on established toxicological points of departure, a critical anatoxin content of macrophyte samples of 3 μg/g f.w. is proposed. Five samples, all taken in Tegeler See and all associated with the water moss Fontinalis antipyretica, exceeded this value. Contents and concentrations of microcystins and cylindrospermopsins did not reach critical levels. The potential exposure risks to anatoxins for children and dogs are assessed and recommendations are given.

Bioactive Metabolites Produced by Cyanobacteria for Growth Adaptation and Their Pharmacological Properties

Cyanobacteria are the most abundant oxygenic photosynthetic organisms inhabiting various ecosystems on earth. As with all other photosynthetic organisms, cyanobacteria release oxygen as a byproduct during photosynthesis. In fact, some cyanobacterial species are involved in the global nitrogen cycles by fixing atmospheric nitrogen. Environmental factors influence the dynamic, physiological characteristics, and metabolic profiles of cyanobacteria, which results in their great adaptation ability to survive in diverse ecosystems. The evolution of these primitive bacteria resulted from the unique settings of photosynthetic machineries and the production of bioactive compounds. Specifically, bioactive compounds play roles as regulators to provide protection against extrinsic factors and act as intracellular signaling molecules to promote colonization. In addition to the roles of bioactive metabolites as indole alkaloids, terpenoids, mycosporine-like amino acids, non-ribosomal peptides, polyketides, ribosomal peptides, phenolic acid, flavonoids, vitamins, and antimetabolites for cyanobacterial survival in numerous habitats, which is the focus of this review, the bioactivities of these compounds for the treatment of various diseases are also discussed.

A comparative study on flocculating ability and growth potential of two microalgae in simulated secondary effluent

The flocculating ability was an important property to microalgal harvesting, especially in secondary effluent. In this study, the flocculating ability of two microalgae, Chlorococcum sp. GD and Parachlorella kessleri TY, was evaluated after 10d of cultivation in secondary effluent. After 180min of settling, the flocculating ability of Chlorococcum sp. GD and P. kessleri TY was 84.43% and 16.23%, respectively. It was suggested that Chlorococcum sp. GD was an excellent self-flocculating microalgae. The mechanism on self-flocculating of Chlorococcum sp. GD was probably related to hydrophobic extracellular polymeric substances (EPS). Besides, compared to P. kessleri TY, the nitrogen and phosphorus removal efficiency of Chlorococcum sp. GD was high, which was up to 66.51% and 74.19%, respectively. Chlorococcum sp. GD also had high lipid content and biomass concentration. Therefore, Chlorococcum sp. GD could be regarded as a promising candidate for microalgal cultivation and harvesting in secondary effluent.