Enhancement of lutein biosynthesis in chlorella vulgaris-1068 under low temperature and luminosity stress conditions

Lutein, a high-value primary carotenoid with a broad range of applications in food, feed, nutraceutical, and pharmaceutical industries, has been widely studied in recent years. The green microalgae Chlorella vulgaris-1068(C.v-1068) screened by our lab showed both a high content in this carotenoid and a high growth rate and has a good profile for lutein production. This work studies the variety of environmental stimulants which enhance cellular accumulation of lutein from C.v-1068. The lutein accumulation and its biosynthesis pathway genes expression were analyzed under low temperature and high luminosity. We find that both cold and high light stresses can induce lutein biosynthesis in C.v-1068. In addition, during dark to light transition also leads to higher lutein productivity and the maximal lutein content (2.86 mg/g DW) was attained after six days dark-cultivated then exposed to 1000 μ photons m-2 s-1 for two days treatment. Consistently, the transcript levels of lutein biosynthesis genes PSY and ZDS were largely enhanced by cold, high light and dark to light transition treatments. And except PSY and ZDS, 1000 μ photons m-2 s-1 luminosity stress also highly increased expression of PDS as compared with low irradiance condition.