Physiological and Biochemical Responses in Microalgae Dunaliella salina, Cylindrotheca closterium and Phormidium versicolor NCC466 Exposed to High Salinity and Irradiation

Abstract

Dunaliella salina (Chlorophyceae), Phormidium versicolor (Cyanophyceae), and Cylindrotheca closterium (Bacillariophyceae) were isolated from three ponds in the solar saltern of Sfax (Tunisia). Growth, pigment contents, and photosynthetic and antioxidant enzyme activities were measured under controlled conditions of three light levels (300, 500, and 1000 µmol photons m−2 s−1) and three NaCl concentrations (40, 80, and 140 g L−1). The highest salinity reduced the growth of D. salina and P. versicolor NCC466 and strongly inhibited that of C. closterium. According to ΦPSII values, the photosynthetic apparatus of P. versicolor was stimulated by increasing salinity, whereas that of D. salina and C. closterium was decreased by irradiance rise. The production of carotenoids in D. salina and P. versicolor was stimulated when salinity and irradiance increased, whereas it decreased in the diatom. Catalase (CAT), Superoxide dismutase (SOD), and Ascorbate peroxidase (APX) activities were only detected when the three species were cultivated under E1000. The antioxidant activity of carotenoids could compensate for the low antioxidant enzyme activity measured in D. salina. Salinity and irradiation levels interact with the physiology of three species that have mechanisms of more or less effective stress resistance, hence different resistance to environmental stresses according to the species. Under these stress-controlled conditions, P. versicolor and C. closterium strains could provide promising sources of extremolyte for several purposes.

Ascorbate‐glutathione cycle alleviates low‐temperature‐induced oxidative stress for augmented growth of Nannochloropsis oceanica Rose Bengal mutants

“…The current results demonstrate a significant increase of APX in H 2 O 2 removal in the RB mutants following exposure to HL (Figure 2). The induction of APX caused by HL stress has been found in other algae (Erickson et al, 2015), such as Haematococcus pluvialis (Park et al, 2008), Dunaliella salina , Phormidium versicolor , C ylindrotheca closterium (Guermazi et al, 2023), and C . reinhardtii (Kuo et al, 2020; Yaisamlee & Sirikhachornkit, 2020).…”

Solar Salterns and Pollution: Valorization of Some Endemic Species as Sentinels in Ecotoxicology

“…Dunaliella spp. (Chlorophyta) possess the unique and remarkable ability to survive in extreme conditions, such as a wide range of NaCl concentrations, intense light, high temperatures, and broad pH values from 1 to 11 [ 99 , 100 , 101 , 102 ]. This species of microalgae is a major constituent of all-natural hypersaline environments and one of the most salt-tolerant life forms [ 34 , 103 , 104 , 105 ].…”

Rapid Induction of Astaxanthin in Haematococcus lacustris by Mild Electric Stimulation

“…This decrease could be attributed to the severe disruption of cellular homeostasis and essential enzyme systems, including esterases, involved in the measurement of ROS. Various biochemical analyses, including the determination of photochemical activity and the ratio of chlorophyll to carotenoid pigments [42], are required to understand the physiological and biochemical responses of microalgae during electrotreatment. Multiple factors, including ROS formation, acidification, and electrolysis of medium components, can affect the electrostimulation of microalgae.…”