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.

本研究调查了 UV/γ 辐射在增强Sorokiniana 小球藻脂质生产方面的潜力. 发现生长、叶绿素含量和光合作用效率在辐照后的不同时间以剂量依赖性方式降低。此外，全基因组转录组分析揭示了分别在 UV (1 J/cm2) 和 γ (1 kGy) 辐射下对光合机制和 DNA 修复/复制相关基因的调节。关键的脂肪酸生物合成相关基因也被上调，这与紫外线和 γ 辐射下总脂质积累分别增加 1.56 倍和 1.73 倍相吻合。三酰基甘油被确定为积累脂质的主要成分之一。补充抗坏血酸（一种生理性 ROS 清除剂）后，与各自的对照相比，UV 和 γ 辐射诱导的脂质积累分别显着降低了 0.66 倍和 0.30 倍，表明 ROS 是脂质积累的主要驱动因素之一。基于 GC-MS 的脂肪酸分析表明，紫外线有利于饱和脂质的积累，而不是不饱和脂质；而 γ 辐射处理的脂质具有更高的必需 omega-3 脂肪酸积累。总之，该研究强调了紫外线和 γ 辐射可诱导脂质快速积累，这将为基于微藻的“食物燃料”应用带来增值。