Study on high-CO(2) tolerant Dunaliella salina and its mechanism via transcriptomic analysis

Microalgae has been regarded as a promising method for reducing CO(2) emission. High CO(2) concentration generally inhibits algal growth, and previous studies have mostly focused on breeding freshwater algae with high CO(2) tolerance. In this study, one marine algal strain Dunaliella salina (D. salina) was grown under 0.03%-30 % CO(2) and 3% NaCl conditions, and was evaluated to determine its potential for CO(2) assimilation. The results showed that D. salina could tolerate 30% CO(2) , and its maximum biomass concentration could reach 1.13 g·L(−1) after 8 days incubation, which was 1.85 times higher than that of incubation in air (0.03%). The phenomenon of high-CO(2) tolerance in D. salina culture was discussed basing on transcriptome analysis. The results showed that D. salina was subjected to oxidative stress under 30% CO(2) conditions, and the majority genes involving in antioxidant system, such as SOD, CAT, and APX genes were up-regulated to scavenge ROS. In addition, most of the key enzyme genes related to photosynthesis, carbon fixation and metabolism were up-regulated, which are consistent with the higher physiological and biochemical values for D. salina incubation under 30% CO(2) .