The effect of saxitoxin and non-saxitoxin extracts of Cylindrospermopsis raciborskii (Cyanobacteria) on cyanobacteria and green microalgae

Abstract

The effect of saxitoxins (STX) on phytoplankton species is poorly understood. To date, no correlation between STX concentrations and phytoplankton physiology has been reported. We investigated the effect of STX (STX+, 0.5-10 μg L −1 total STX) and non-STX (STX−, 0.5-10 μg L −1 total STX biomass equivalent) extracts of Cylindrospermopsis raciborskii on Microcystis wesenbergii BCCUSP11, Microcystis aeruginosa BCCUSP232 (microcystin producing), Scenedesmus acuminatus UFSCar036, and Monoraphidium convolutum CMEA/UFF0201 under controlled laboratory conditions. Both STX+ and STX− extracts inhibited the cell density and specific growth rate of M. wesenbergii, M. aeruginosa, and S. acuminatus. However, the effect of STX+ extract on the phytoplankton strains was significantly higher than that of STX− extract. M. convolutum, on the other hand, was tolerant as both STX+ and STX− extracts did not significantly reduce its cell density and specific growth rate (day −1). The exposure of M. aeruginosa to STX+ and STX− resulted in higher total (intracellular and extracellular) microcystin concentration than the control. STX concentrations had a significant negative correlation with cell density and growth response of the phytoplankton strains investigated in this study. Conclusions can be made that although both STX+ and STX− extracts of C. raciborskii inhibited the growth of some phytoplankton species, the STX+ extracts were more toxic. Keywords Growth inhibition. Cyanotoxins. Phytoplankton. dc-Saxitoxin. Neo-saxitoxin. Microcystins on sodium channels in both prokaryotes and eukaryotes (Neilan et al. 2013). STX are of high ecotoxicological risk due to the toxicity they induce in fish, mussels, copepods, mammals, and birds (Landsberg 2002). A number of cyanobacteria such as Aphanizomenon flos-aquae, Cylindrospermopsis raciborskii, Lyngbya spp., and Anabaena spp. synthesize STX in freshwater ecosystems. However, the production of this group of toxins tends to be strain specific (Molica et al. 2002; Bernard et al. 2003; Wiegand and Pflugmacher 2005; Al-Tebrineh et al. 2010). The discovery that C. raciborskii produces STX and cylindrospermopsin has made it an important cyanobacterium to be monitored in aquatic ecosystems. This is due to the increased frequency of its occurrence, scientific interest, improved water quality monitoring, availability of suitable habitat, and in some cases, its invasion of new habitats (Figueredo et al. 2007; Kling 2009; Sukenik et al. 2012). The cosmopolitan and increasing distribution of C. raciborskii is easily traced to its ecophysiological adaptation and tolerance to changing physicochemical

Reviewing Interspecies Interactions as a Driving Force Affecting the Community Structure in Lakes via Cyanotoxins

“…The inhibitory effects of STX on phytoplankton species were reported by Do Carmo Bittencourt-Oliveira et al [ 160 ]. Following exposure to both STX-containing (0.5–10 μg L −1 ) and STX-deficient extracts of R. raciborskii , the growth of a toxic M. aeruginosa strain and non-MC producing strains of M. wesenbergii , as well as the green algae Tetradesmus lagerheimii (previously Scenedesmus acuminatus ) was inhibited.…”

“…However, the inhibitory effects of the STX-containing extracts were greater than the non-STX extracts and were positively related to the concentration of STX. Both extracts enhanced the total MC content of toxic M. aeruginosa [ 160 ]. Since the purified STX (0.75–48 μg L −1 ) had no growth inhibitory effect on the growth of C. reinhardtii [ 161 ], it would be of great value to better characterize the chemical composition of the crude extracts to clarify the potential contribution of the other bioactive compounds that may influence the observed toxicity.…”

CIANOBACTÉRIAS E CIANOTOXINAS EM AMBIENTES AQUÁTICOS: uma breve revisão sobre os principais métodos detecção, remoção e impactos sobre a saúde humana = CYANBACTERIA AND CYANOTOXINS IN AQUATIC ENVIRONMENTS: a short review on the main methods of detection, removal and impacts on human health

“…2021 cianotoxinas. Há na literatura a aplicação de ensaios crônicos em análise histopatológica de peixes cultivados em viveiros (DROBRAC et al, 2016) e tilápias (HAUSER-DAVIS et al, 2015), trabalhos utilizando algas verdes e outras cianobactérias (ação antibiose) (BITTENCOURT-OLIVEIRA et al, 2016). Comumente são aplicados, ainda, ensaios ecotoxicológicos com o peixe zebrafish (Danio rerio), ou paulistinha, em estudos sobre mecanismos de intoxicação hepática, teratotogenese, reprodução, embriogenese e ciclo de vida (QI et al, 2016;HOU et al, 2016;LI et al, 2015;QIAO et al, 2013;PAVAGADHI et al, 2012).…”