The eurythermal adaptivity and temperature tolerance of a newly isolated psychrotolerant Arctic Chlorella sp.

Abstract

A new strain of Chlorella sp. (Chlorella-Arc), isolated from Arctic glacier melt water, was found to have high specific growth rates (μ) between 3 and 27°C, with a maximum specific growth rate of 0.85 day −1 at 15°C, indicating that this strain was a eurythermal strain with a broad temperature tolerance range. To understand its acclimation strategies to low and high temperatures, the physiological and biochemical responses of the Chlorella-Arc to temperature were studied and compared with those of a temperate Chlorella pyrenoidosa strain (Chlorella-Temp). As indicated by declining F v /F m , photoinhibition occurred in Chlorella-Arc at low temperature. However, Chlorella-Arc reduced the size of the light-harvesting complex (LHC) to alleviate photoinhibition, as indicated by an increasing Chl a/b ratio with decreasing temperatures. Interestingly, Chlorella-Arc tended to secrete soluble sugar into the culture medium with increasing temperature, while its intracellular soluble sugar content did not vary with temperature changes, indicating that the algal cells might suffer from osmotic stress at high temperature, which could be adjusted by excretion of soluble sugar. Chlorella-Arc accumulated protein and lipids under lower temperatures (<15°C), and its metabolism switched to synthesis of soluble sugar as temperatures rose. This reflects a flexible ability of Chlorella-Arc to regulate carbon and energy distribution when exposed to wide temperature shifts. More saturated fatty acids (SFA) in Chlorella-Arc than Chlorella-Temp also might serve as the energy source for growth in the cold and contribute to its cold tolerance.

Ecophysiological Features of Polar Soil Unicellular Microalgae1

“…In contrary to our results, Cao et al. () observed higher growth rates of 0.85 · d −1 at 15°C. However, it was also shown (Shukla et al.…”

“…However, one out of the major limitations in biotechnological applications of polar unicellular microalgal strains is their remarkably slow growth (Cao et al. ). The growth rate of the most rapidly growing a cold‐adapted microalga at the temperature yielding the maximum growth rate is less than that of a micro‐alga adapted to “temperate” temperatures (Eppley ).…”

Improvement on lipid production by Scenedesmus obliquus triggered by low dose exposure to nanoparticles

“…Rapid light curves (RLCs) were performed according to a pre-installed software routine. rETR max (the relative maximum Electron Transport Rate) was calculated from the RLCs 52 .…”

Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair

“…It can be found in a diverse range of habitats such as in soil, freshwater lakes, ponds, marine and brackish waters, and snow as well as in hot springs [ 48 – 49 ]. Studies have reported that Chlorella strains isolated from Antarctic and Arctic are eurythermal, able to grow at temperatures ranging from 4–30°C and 3–27°C, respectively [ 35 , 50 ]. Chlorella is an ideal experimental organism for investigating various research questions and has potential applications in biotechnology [ 48 ].…”