Effect of NaCl salinity on the growth, metabolites, and antioxidant system ofMicrocystis aeruginosa

Abstract

The physiological and biochemical adaptations of the cyanobacterium Microcystis aeruginosa, grown in a saline environment, were estimated. M 11 cultures were exposed to variable salt concentrations (0.5, 1.0, 2.0, and 4.0 g NaCl L À1 ). The cell density and chlorophyll contents decreased with increasing salinity. The carbohydrate and protein contents were enhanced under lower salinities. The data demonstrated that M. aeruginosa could endure an osmotic potential of 4.0 g NaCl L À1, whereas growth was inhibited under hypersaline conditions above 2.0 g NaCl L À1. The antioxidant activities were evaluated, with salt stress exacerbating membrane lipid peroxidation as indicated by an increasing malondialdehyde (MDA) content. Obvious alterations in the antioxidant enzymes were diverse between the hypo and hypersalinities. Under the hyposaline treatments, high contents of superoxide dismutase (SOD) and catalase (CAT) were detected, whereas hypersaline treatments induced a decrease compared to the control. Accordingly, salinity might be a controlling factor inhibiting cyanobacterial blooms in saline lakes of the Mongolia-Xinjiang plateau, China.

Changes in metabolites, antioxidant system, and gene expression in Microcystis aeruginosa under sodium chloride stress

“…Several studies suggest that salinity plays a major role in determining algal proliferation (Sellner et al, 1988;Tonk et al, 2007). Our results were consistent with previous studies (Orr et al, 2004;Zhang et al, 2013). This implies that a sudden salinity increase may lead to a reduction of algal density (Tonk et al, 2007).…”

“…Previous studies on the effects of NaCl on M. aeruginosa have focused on algal growth and chlorophyll content (Lehman et al, 2005;Ross et al, 2006;Zhang et al, 2013). Here we further investigated the effect of NaCl on the transcription of photosynthesis-related genes psbA and rbcL.…”

“…Similarly, lower salinities in San Francisco Bay Estuary lead to comparatively high concentration of MCs (Lehman et al, 2005). In addition, some laboratory studies have demonstrated that sodium chloride affected the production of metabolites and photosynthesis in cyanobacteria (Black et al, 2011;Hu et al, 2014;Lu and Vonshak, 2002;Zhang et al, 2013). Most of these studies only measure the changes of physiological parameters after exposure to sodium chloride, whereas information on the transcriptional regulation of related genes in M. aeruginosa is still scarce.…”

Effects of NaCl and Na2CO3 stresses on photosynthetic ability of Chlamydomonas reinhardtii

“…In cyanobacteria, the PSII mediated transport of electrons from water to DCIP (electron acceptors in PSII) was interfered under NaCl stress (Allakhverdiev et al 2000). In addition, NaCl stress can decrease the production of secondary carotenoid astaxanthin in algae (Orosa et al 2001;Pelah et al 2004), but increase the content of reactive oxygen species (ROS) (Tang et al 2007;Zhang et al 2013), glycerol pool (Goyal 2007), emission of volatile organic compounds (VOCs) (Zuo et al 2012a), and activities and expression levels of antioxidant enzymes (Yoshida et al 2004;Zhang et al 2013). Severe NaCl and KCl stresses even cause programmed cell death (PCD) in the green algae Micrasterias denticulate (Affenzeller et al 2009).…”

The limit of resistance to salinity in the freshwater cyanobacterium Microcystis aeruginosa is modulated by the rate of salinity increase

“…However, the rate of environmental change (salinity increment) could determine the limit of resistance to salinity in this species. It must be highlighted that most of the studies focused on the effect of increased salinity on M. aeruginosa assessed the performance of cells after only a few generations (less than ten) submitted to high salinity (Martínez de la Escalera et al, 2017; Miller et al, 2010; Rosen et al, 2018; Orr, Jones, & Douglas, 2004; Otsuka et al, 1999; Prinsloo & Pieterse, 1994; Tonk, Bosch, Visser, & Huisman, 2007; Verspagen et al, 2006; Zhang, Xu, & Xi, 2013). Consequently, these results could be interpreted as evidence of cell regulation and acclimation (Borowitzka, 2018).…”