Proteomic analysis reveals mechanisms of mixed wastewater with different N/P ratios affecting the growth and biochemical characteristics of Chlorella pyrenoidosa

Effects of different nutrient ratios on the biochemical compositions of microalgae and the changes were rarely studied at the molecular level. In this study, the impacts of various nitrogen to phosphorus (N/P) ratios on growing of C. pyrenoidosa, as well as biochemical compositions and the metabolic regulation mechanism in mixed sewage, were investigated. The results suggested that 18 was optimal N/P ratio, while the dry weight (1.0 g/L), chlorophyll-a (Chla) (3.63 mg/L), and lipid production (0.28 g/L) were all the highest comparing with other groups. In contrast, the protein production (0.37 g/L) was the least. The nature of the regulatory mechanisms in the metabolic pathways of these biochemical compositions was revealed by proteomic results, and there were 62 different expression proteins (DEPs) taken part in fatty acid and lipid biosynthesis metabolism (FA), amino acid biosynthesis metabolism (AA), photosynthesis (PHO), carbon fixation in photosynthetic organisms (CFP), and central carbon metabolism (CCM).