Revelation of microalgae's lipid production and resistance mechanism to ultra-high Cd stress by integrated transcriptome and physiochemical analyses

The ultra-high Cd polluted environment is a special habitat in nature. Analysis of the biological adaptation and resistance mechanism of Auxenochlorella protothecoides UTEX234 to ultra-high Cd stress would offer some inspiring understanding on Cd detoxification mechanism and help discovering highly active bioremediation agents. In this study, integrated analyses of the transcriptome, multi-physiological and biochemical data and fatty acid profilings of UTEX2341 were performed for the first time. It was found that exogenous Ca ions could alleviate Cd stress. Manganese-dependent superoxide dismutase and peroxidase also participated in intracellular detoxification. And non-enzymatic antioxidants rather than one specific enzymatic antioxidant were suggested to be used as “core antioxidants”, which witnessed better performance in Cd detoxification. In addition, Cd stress improved sixteen alkane value and biofuel yield and quality. [Display omitted] •Non-enzymatic antioxidants played more important roles than enzymatic antioxidants.•Exogenous Ca ions could alleviate Cd stress.•Nramp, MATE, ZIP, CE, ABC family and Ca2+-ATPase participated in Cd transport.•Cd stress improved the sixteen alkane value, the yield and quality of biodiesel. Under ultra-high Cd stress, non-enzymatic antioxidants were suggested to be as “core antioxidants” in microalgae's detoxification.