Contents lists available at ScienceDirect Harmful Algae journal homepage: www.elsevier.com/locate/hal Review Cyanotoxin cylindrospermopsin producers and the catalytic decomposition process: A review. Michal Adamski a, ⁎ , Konrad Wołowski a , Ariel Kaminski b , Alica Hindáková c a Department of Phycology, W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, 31-512 Kraków, Poland b Department of Plant Physiology and Development, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland c Department of Cryptogams, Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 23 Bratislava, Slovak Republic ARTICLE INFO Keywords: Cyanobacteria Cylindrospermopsin Cyanotoxins Catalytic decomposition ABSTRACT Cylindrospermopsin (CYN) is a toxic secondary metabolite produced by several freshwater species of cyano- bacteria. Its high chemical stability and wide biological activity pose a series of threats for human and animal morbidity and mortality. The biggest risk of CYN exposure for human organism comes from the consumption of contaminated water, fsh or seafood. Very important for efective monitoring of the occurrence of CYN in aquatic environment is accurate identifcation of cyanobacteria species, that are potentially able to synthesize CYN. In this review we collect data about the discovery of CYN production in cyanobacteria and present the morpho- logical changes between all its producers. Additionally we set together the results describing the catalytic de- composition of CYN. 1. Introduction Harmful algal blooms (HABs) occurring all over the world constitute serious ecological problems and contribute to biodiversity decline in aquatic environments. The massive development of cyanobacteria or algae radically worsens conditions in water reservoirs due to the ex- cessive use of oxygen, increases the turbidity of water and disrupts trophic networks (Huisman et al. 2018, Krztoń et al. 2019, Hipsher et al. 2020). It is believed that human activity, such as the production of sewage, waste and high intensity agriculture, has the greatest impact on the intensifcation of these phenomena (Pereira et al. 2017, Park et al. 2017, Zuo 2019). Consequently, increased concentrations of biogenic chemical elements and the creation of favorable conditions for cyanobacteria or algae growth are observed. Moreover, many re- searchers have linked the formation of optimal conditions for cyano- bacteria or algae in places where blooms have not occurred so far with climate change and global warming (Mazard et al. 2016, Visser et al. 2016, Yan et al. 2017). HABs are particularly dangerous and require attention due to pro- duce toxic secondary metabolites, called cyanotoxins, that are released into the water (De la Cruz et al. 2013, Adamski et al. 2014, González- Pleiter et al. 2020). In recent years, cylindrospermopsin (CYN) has been one of the most commonly studied cyanotoxins (Merel et al. 2013, Moreira et al. 2013, Flores-Rojas et al. 2019). CYN is an alkaloid (C 15 H 21 N 5 O 7 S; 415.43 Da) with a tricyclic gua- nidine moiety, a sulfate group and a uracil ring (Fig. 1) (Ohtani et al. 1992). The biological activity of this compound is wide and includes disruptions of several metabolic pathways. Primarily, CYN is an efec- tive inhibitor of protein biosynthesis in both animal and plant cells (Harada et al. 2004, Metcalf et al. 2004, De la Cruz et al. 2013). The results of many studies have shown that the infuence of CYN leads to damage to nucleic acids and carcinogenesis (Pichardo et al. 2017). CYN also increases the concentration of free oxygen radicals and causes oxidative stress (Štraser et al. 2013). Moreover, it was demonstrated to drastically disrupt the proliferation of animal cells and reduce the mi- totic index (Humpage et al. 2005, Moreira et al. 2013). The above information clearly indicated that CYN is one of the most dangerous compounds synthesized by cyanobacteria. Therefore, it is a serious threat to organisms that live in ecological niches similar to cyanobacteria and to people using aquatic reservoirs in which HABs occur. To date, many researchers have made eforts to broaden the knowledge about the fate of CYN in the environment and to develop efective methods to remove CYN from water. In recent decades, many interesting and innovative results on this topic have been published. However, in these papers, information about cyanobacteria that are able to synthesize CYN is limited. A summary of data characterizing CYN producers could be helpful in future studies and potentially https://doi.org/10.1016/j.hal.2020.101894 Received 24 February 2020; Received in revised form 18 August 2020; Accepted 22 August 2020 ⁎ Corresponding author. E-mail address: m.adamski@botany.pl (M. Adamski). Harmful Algae 98 (2020) 101894 1568-9883/ © 2020 Elsevier B.V. All rights reserved. T