Response of Scenedesmus quadricauda (Chlorophyceae) to Salt Stress Considering Nutrient Enrichment and Intracellular Proline Accumulation

Abstract

Aquatic organisms are exposed to a wide range of salinity, which could critically affect their survival and growth. However, their survival and growth response to salinity stress remain unclear. This study evaluates the growth response and intracellular proline accumulation of green algae, Scenedesmus quadricauda, isolated from brackish water, against dissolved salts stress with N and P enrichment. We tested a hypothesis that nutrient enrichment can relieve the dissolved salts stress of algae by accumulating intracellular proline, thereby improving survival and growth. Four levels of salinity (0, 3, 6, 12 psu) were experimentally manipulated with four levels of nutrient stoichiometry (N:P ratio = 2, 5, 10, 20) at constant N (1 mgN/L) or P levels (0.05 and 0.5 mgP/L). In each set of experiments, growth rate and intracellular proline content were measured in triplicate. The highest level of salinity inhibited the growth rate of S. quadricauda, regardless of the nutrient levels. However, with nutrient enrichment, the alga showed tolerance to dissolved salts, reflecting intracellular proline synthesis. Proline accumulation was most prominent at the highest salinity level, and its maximum value appeared at the highest N:P ratio (i.e., highest N level) in all salinity treatments, regardless of P levels. Therefore, the effects of P and N on algal response to salt stress differ.

Effects of Nutrient Content and Nitrogen to Phosphorous Ratio on the Growth, Nutrient Removal and Desalination Properties of the Green Alga Coelastrum morus on a Laboratory Scale

“…Our results also revealed that higher nutrient content favors to withstand against the negative effects of high chloride concentrations, especially in the case of longer exposure times. These observations are in accordance with the results of Park et al about another coenobial green alga, Scenedesmus quadricauda [41]. It seems that similarly to S. quadricauda and other coenobial green algae (e.g., Scenedesmus bijugatus [42]), the studied Coelastrum morus requires different N:P ratios for its survival under different salinity levels.…”

Comparison of phytoplankton community structure in two tropical estuaries of East Coast of India

“…Lower salinity perhaps triggered the Chlorophycean growth in the Mahanadi estuarine water. In a study by Park et al [39], they investigated the growth of chlorophyte Scenedesmus quadricauda in the experiments designed to have the salinity level 0, 3, 6, 12 psu with manipulated N:P ratio of 2, 5, 10, 20 at constant N and P concentrations alternately.. The experimental set up with highest salinity ended up with inhibited growth of the alga.…”

Current Studies of the Effects of Drought Stress on Root Exudates and Rhizosphere Microbiomes of Crop Plant Species

“…Although these strategies are promoted by plants, the contribution of bacteria also affects this protection. For example, although proline serves as the most vital osmotic agent in the plant cytoplasm, under environmental stress, proline accumulation occurs not only in higher plants but also in bacteria, which may also help the bacteria for drought tolerance and then in association with plant in resisting drought [54,55]. Rolli et al (2016) showed that improved plant resistance to drought is promoted by the root-associated microbiome as a water stress-dependent trait [56].…”