Co-production of lutein and fatty acid in microalga Chlamydomonas sp. JSC4 in response to different temperatures with gene expression profiles

Temperature has been regarded as an important factor for microalgal growth and the accumulation of lutein and fatty acid. In this study, the lutein and fatty acid producing microalga Chlamydomonas sp. JSC4 was cultivated at various temperatures (20, 25, 30, 35, and 40 °C). Maximum biomass productivity (1271 mg/L/d) and lutein productivity (3.27 mg/L/d) were achieved at 35 °C, whereas the highest lutein content (3.82 mg/g) was obtained at 20 °C. Similarly, maximum total fatty acid (TFA) productivity (177.31 mg/L/d) was obtained at 35 °C, yet TFA content (202.56 mg/g) was highest at 20 °C with increased unsaturated fatty acid proportion. It was observed that carotenoid, fatty acid, and protein contents increased, but carbohydrate content decreased at low temperature, which could be due to the modulation of metabolic flux from carbohydrate to carotenoid, fatty acid and protein. Inspection of gene expression profile showed that the lutein biosynthesis genes (psy, pds, and lut1) and fatty acid biosynthesis genes (bccp and bc) were upregulated at 20 °C when nitrate was replete and at the beginning of nitrate depletion. This study will help to develop temperature manipulation strategy and provide molecular basis of genetic engineering for improvement of the co-production of lutein and fatty acid in strain JSC4.