UV and ?-radiation induced molecular changes for rapid lipid accumulation in Chlorella sorokiniana

The present study investigated the potential of UV/gamma-radiation for enhancing lipid production in Chlorella sorokiniana. The growth, chlorophyll content and photosynthesis efficiency were found to be reduced, at variable time post-irradiation, in a dose-dependent manner. Further, whole-genome transcriptomic profiling revealed the modulation of photosynthetic machinery and DNA repair/replication related genes under UV (1 J/cm2) and gamma (1 kGy)-radiation, respectively. The key fatty acid biosynthesis related genes were also upregulated which coincided with 1.56- and 1.73-fold increase in total lipid accumulation under UV and gamma-radiation, respectively. The triacylglycerol was identified as one of the major constituents of accumulated lipid. Upon ascorbic acid (a physiological ROS scavenger) supplementation, UV and gamma-radiation induced lipid accumulation was significantly decreased by 0.66- and 0.30-fold, respectively compared with their respective controls, indicating ROS as one of the major drivers of lipid accumulation. GC-MS based fatty acid profiling revealed that UV favored the accumulation of saturated over unsaturated lipids; while, gamma-radiation treated lipid had a higher accumulation of an essential omega-3 fatty acid. Taken together, the study highlighted UV and gamma-radiation for inducing rapid lipid accumulation, which will impart value addition to microalgae-based food-fuel application.

Automated summary

This study investigates the potential of UV/gamma-radiation for enhancing lipid production in Chlorella sorokiniana. The results show that growth, chlorophyll content, and photosynthesis efficiency decrease in a dose-dependent manner after irradiation. Transcriptional profiling reveals the modulation of photosynthetic and DNA repair/replication genes under UV and gamma radiation. Upregulated fatty acid biosynthesis genes coincide with increased total lipid accumulation under UV and gamma radiation. Ascorbic acid supplementation reduces UV and gamma radiation-induced lipid accumulation, indicating ROS as a major driver. Fatty acid analysis shows that UV favors the accumulation of saturated lipids, while gamma radiation treated lipids have a higher accumulation of essential omega-3 fatty acid.