Influence of salinity on the growth and biochemical composition of the cyanobacterium Synechococcus sp.

Abstract

The study of cyanobacteria isolated from hypersaline environments is of interest because of their metabolic and ecophysiologic versatility in adapting to extreme conditions of salinity, temperature, irradiance and nutrient availability. The effect of salinity at 0‰, 35‰, 70‰ and 100‰ on the growth, dry weight, and pigment, protein, carbohydrate and lipid production of the cyanobacterium Synechococcus sp. was determined. Bioassays were kept in ALGAL medium equivalent to 8 mM NaNO3, constant aeration, 12:12 h photoperiod, 28 ± 2ºC and 156 µmol quanta m–2 s–1 of irradiance. The cyanobacterium was able to grow under all salinities tested. Cell density was optimized at 35‰, with 607.64 ± 14.35 cells mL–1. The highest values of dry weight (3.87 ± 0.03 ng cell–1), chlorophyll a (41.86 ± 0.39 fg cell–1), ß-carotene (9.03 ± 0.15 fg cell–1), zeaxanthin (9.74 ± 0.24 fg cell–1), proteins (1.95 ± 0.05 pg cell–1) and carbohydrates (1.80 ± 0.05 pg cell–1) were obtained at 100‰; however, the highest lipid content (0.45 ± 0.04 pg cell–1) was reached at 0‰. This Synechococcus strain shows halotolerance and the capacity to modulate the production of enriched biomass with pigments, proteins, carbohydrates and lipids in terms of salinity.

Improvement of the growth of Arthrospira (Spirulina) platensis from Toliara (Madagascar): Effect of agitation, salinity and CO2 addition

“…The enhanced respiration indicates that the response ta salin ity stress is an energy consuming process (Zeng and Vonshak, 1998) but the mechanisms have not yet been elucidated. It is probable that salinity stress affects light utilization and metabolism (particularly carbohydrates involved in osmoreg ulation) ta counteract ionic and osmotic stresses (Kebede, 1997;Rosales et al, 2005). Sorne authors have reported an increase in growth with salinity (Dhiab et al, 2007) but they measured Arthrospira growth by following the chlorophyll con tent, which was not the case in our study.…”

“…The decrease in growth with increasing salinity has fre quently been reported in the literature (Rosales et al, 2005;Vonshak et al, 1988;Zeng and Vonshak, 1998;Kebede, 1997). It is accompanied by a decrease in photosynthetic effi.ciency, phycobilin/Chla ratio and PSII activity and an increase in car bohydrate metabolism (Vonshak et al, 1988;Warr et al, 1985).…”

Biochemical composition of seven species of cyanobacteria isolated from different aquatic habitats of Western Ghats, Southern India

“…For example, Olvera -Ramirez et al (2000) reported the fatty acid content in Calothrix sp., isolated from a rice field in Mexico, was influenced by the nitrate content in the culture medium and its polyunsaturated fatty acid content was more. The effect of light, temperature and salinity on the lipid and fatty acid composition in some species isolated from different habitats have also been reported by many workers (Rezanka et al, 2003;Maslova et al, 2004;Liu et al, 2005;Rosales et al, 2005). Besides, lipids and fatty acids play an important role in the tolerance of cyanobacterial cells to various environmental stresses such as desiccation, salt induced damage, low temperature, high light induced photoinhibition (Singh et al, 2002).…”

“…Cyanobacteria contain a variety of amino acids and hormonal substances along with sugars and are involved in the improvement of soil texture by acting as chelating agents for heavy metals; they may stimulate the growth of heterotrophic bacteria and also act as growth promoting substances for the plants (Misra and Kaushik, 1989). The biochemical constituents of cyanobacteria depends on the nature of strains, physiological state of the culture and the environment (Vargas et al, 1998;Subhashini et al, 2003;Maslova et al, 2004;Rosales et al, 2005). Subhashini et al (2003) observed significant variations in protein content among the four isolates of Anabaena azollae.…”

“…Authors also stressed about the biochemical variations that enabled to distinguish between the subspecies in several cyanobacterial genera. Rosales et al (2005) reported about the physiological competence of Synechococcus sp. in hypersaline medium.…”