NaCl as an excellent trigger-induced biodiesel production and phenol-containing wastewater treatment in a novel salt-tolerant microalgae Ankistrodesmus sp. ACC

This study investigates how high salt stress enhances lipid buildup and phenol removal in Ankistrodesmus sp. ACC. NaCl is a better trigger for treating phenol wastewater (nearly 100 % nitrogen, phosphorus and phenol removal) and producing high-quality biodiesel (0.37 g/L•d). Multi-omics data revealed significant increases in nicotinamide-adenine-dinucleotide phosphate (NADPH), adenosine-triphosphate (ATP), Ca-dependent kinases, serine/threonine-protein kinase, and the Na/Ca exchanger to mitigate Na⁺-induced ROS. Elevated ATP and NADPH levels support increased activity in the pyruvate-malate cycle and electron transport activity system (ETAS), which enhances phenol removal and further promotes the tricarboxylic acid cycle (TCA). The TCA cycle operates to generate a carbon skeleton to provide energy for microalgal metabolism or growth. In addition, nitrogen pollutants are converted into starch and triglycerides, providing a material energy basis for the adaptation of microalgae to salt stress. These insights deepen our understanding of contaminants degradation and lipid synthesis by microalgae under high salt stress