The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

Microalgae gain increasing attention due to their capabilities in bio-oil production, CO₂ sequestration and water treatment. Snow algae, which thrive in severe cold conditions such as high latitudes and high altitudes on Earth, have significant application potential in these areas, but they have yet to be completely studied and used. In this study, we cultivated the facultatively psychrophilic Chloromonas typhlos under laboratory conditions (35 µmol photons m^-2 s^-1、2.0% v/v CO₂, room temperature) and evaluated its ability to produce biofuels, fix CO₂, and absorb nitrogen and phosphorus from anaerobic digestates. After a 28-day cultivation, the biomass density in the culture system peaked at 5.3 g DW L^-1, with a productivity rate of 183 mg L^-1 d^-1. The microalgae exhibited high photosynthetic efficiency, as indicated by the high electron transport rate (rETR), which facilitated an impressive CO₂ fixation rate of 320 mg L^-1 d^-1. On the 14th day, the removal rates of N-NH₄⁺, N-NO₃^-, P-PO₄^3- were 90.9%, 95.9%, and 91.7%, respectively. Under the nitrogen-limited condition, the lipid content escalated from 22% to 59% on a dry weight basis, accompanied by a lipid productivity rate of 107 mg L^-1 d^-1. At the end, the photosynthetic pigment contents decreased by 71.8%, and non-photochemical quenching (NPQ) remarkably increased by 18 times. These physiological responses may be photoprotective strategies of C. typhlos to cope with the excess energy under nitrogen starvation stress. The outcomes indicate that the snow alga possesses considerable potential and merits for applications in algal oil production, CO₂ fixation, and the remediation of nitrogen and phosphorus from water bodies.
 

Chloromonas typhlos, biofuels, CO2 capture, water treatment, application