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

Abstract

The present study investigated the potential of UV/γ-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 γ (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 γ-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 γ-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, γ-radiation treated lipid had a higher accumulation of an essential omega-3 fatty acid. Taken together, the study highlighted UV and γ-radiation for inducing rapid lipid accumulation, which will impart value addition to microalgae-based “food-fuel” application.