Antioxidants alleviated low-temperature stress in microalgae by modulating reactive oxygen species to improve lipid production and antioxidant defense

The aim of this study was to investigate the effects of various concentrations of antioxidants, including butyl hydroxy anisd (BHA), butylated hydroxytoluene (BHT), fulvic acid (FA), melatonin (MT), glycine betaine (GB) and putrescine (Put), on growth and lipid synthesis of microalgae under low-temperature (15 ℃). Changes in biochemical indicators, reactive oxygen species (ROS) level, glutathione (GSH) content and antioxidant enzyme activities were also studied. The results indicated that the maximum biomass concentration (1.3 g/L) and lipid productivity (75.3 ± 5.8 mg/L d^-1) were achieved under 100 μM MT and 1 μM GB, respectively. Moreover, antioxidants were able to increase the GSH and antioxidant enzymes activities in algal cells under low-temperature stress. This study was enlightening for the utilization of antioxidants to improve the resistance to low-temperature stress and lipid production in microalgae, and provided a theoretical basis for the application of microalgae for lipid accumulation in cold regions.