| With the microalga Monoraphidium sp. QLY-1 as the research object, the effects of exogenous melatonin (MT) on the biomass, lipid content, contents of carbohydrate and protein, reactive oxygen species (ROS), malondialdehyde (MDA) and activities of three key antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in Monoraphidium sp. QLY-1 under nitrogen deficiency condition were investigated. The results showed that affter the treatment of exogenous MT, the lipid content in algal cells was 1.22 times as high as that of the control, and the highest lipid content reached 51.38%. The contents of protein and carbohydrate decreased from 20.82% and 37.69% to 14.73% and 25.24% respectively. Furthermore, the addition of MT reduced the contents of ROS and MDA in the algal cells and increased the activities of three antioxidant enzymes, and alleviated algal cell oxidative damage caused by nitrogen deficiency. The exogenous MT could further promote the accumulation of lipid in microalgae under nitrogen deficiency condition by regulating the ROS level and the antioxidant enzymes activities, which provided a novel strategy for the synthesis of lipid in microalgae. |
