Polysaccharides as a protective response against microcystin-induced oxidative stress in Chlorella vulgaris and Scenedesmus quadricauda and their possible significance in the aquatic ecosystem

Abstract

Toxic cyanobacteria occur worldwide in aquatic ecosystem, and their toxins have adverse effects on most aquatic organisms. However, some species of green algae can grow and flourish at environmentally relevant concentrations of microcystins (MCYSTs). Therefore, the present study aimed to investigate the possible adaptive response of two representatives of green algae, Chlorella vulgaris and Scenedesmus quadricauda to these toxins. Growth and antioxidative biomarkers of these algae were studied over a 14-day exposure to different concentrations of pure microcystin-LR (MCYST-LR) and crude MCYSTs. Both pure and crude MCYSTs significantly decreased the growth of the two algae compared to control cultures during the first 3 days of incubation. Meanwhile, increases in glutathione-S-transferase (GST), glutathione peroxidase (GPX) and lipid peroxidation, and decreases in glutathione (GSH) were also observed in toxin-treated cultures. All growth and biochemical variables were restored to control levels after 3 days of incubation and remained at levels near to those of control cultures during the remaining period of experiment. The changes in these variables correlated with polysaccharide contents of toxin-treated cultures, indicating the involvement of these polysaccharides in protecting the algal cells against MCYST-induced oxidative stress. The results of in vitro assay of antioxidant activity revealed that these polysaccharides had different activities, depending on their sulfate contents. This study provides an evidence for the first time that polysaccharides play a protective role in some microalgae against MCYST-induced oxidative stress.

Effects of UV radiation on five marine microphytobenthic Wadden sea diatoms isolated from the Solthörn tidal flat (Lower Saxony, southern North Sea) – Part I: growth and antioxidative defence strategies

“…Similar observations have been reported by different authors (e.g. Nagayama et al, 2003;Affan et al, 2006;Goh et al, 2010) and are consistent with the fact that microalgae, and in particular diatoms, bear a number of antioxidant compounds, including carotenoids, polyunsaturated fatty acids and polysaccharides (Mohamed, 2008;Holtin et al, 2009;Scholz et al, 2014). In contrast, both the long-term UV-B-and combined UV-treatments of the five diatom taxa showed significant correlations between the DPPH and FRAP assays and the total phenolic contents (P < 0.05), suggesting that phenolic compounds could be involved in acclimatization to at least UV-B long-term exposure.…”

A Comparison of the Antioxidant Properties and Total Phenolic Content in a Diatom, Chaetoceros sp. and a Green Microalga, Nannochloropsis sp.

“…This indicates that phenolic compounds might not be a major contributor to the antioxidant capacities for either of these microalgae. The fact that the microalgae contain various antioxidant compounds, such as carotenoids, polyunsaturated fatty acids and polysaccharides, further supports this observation (Mohamed, 2008;Holtin, Kuehnle, Rehbein, Schuler, Nicholson, & Albert, 2009). Although phenolic compounds are found to be the major contributor to antioxidant activities in many higher-order species of such as plants, this might hold true for microalgae.…”

Dynamic of functional epigenotypes Dunaliella viridis Teodor. at cumulative and quasicontinuous cultivation

“…Известно, что в процессе роста микроводоросли D. viridis экскрети-руют в среду полисахариды (Mohamed, 2008;Angelis et al, 2012;Fiori et al, 2012;Geun Goo et al, 2012). Интерес к ЭПС микроводорослей свя-зан с их возможным использованием:…”