Eco-technological method for carbon dioxide biosorption and molecular mechanism of the RuBisCO enzyme from unicellular microalga Chlorella vulgaris RDS03: a synergistic approach

In the present study, we used a bubble column photobioreactor to test carbon dioxide using Chlorella vulgaris RDS03 under laboratory conditions. The nutrient concentration of medium was optimized by Box-Behnken design through response surface methodology (RSM), and regression coefficient ( R 2 ) value of 0.999 was analyzed by analysis of variance (ANOVA). The microalga Chlorella vulgaris RDS03 was captured—98.86% of CO 2 analyzed by CO 2 utilization and biofixation kinetics, 310U mL −1 of RuBisCO enzyme, 5.32 mg mL −1 of biomass, 124 mg g −1 of carbohydrate, 247.15 mg g −1 of lipid, 4.1 mL g −1 of bioethanol, and 4.9 mL g −1 of biodiesel produced. The molecular weight of purified RuBisCO enzyme was analyzed as 54 kDa by 15% of SDS PAGE. The 3D homology structure of N-terminal amino acids sequence of RuBisCO was predicted with 415 amino acid residues. The biodiesel was subjected to functional group analysis using Fourier transform infrared spectroscopy (FTIR). The fifty biodiesel (FAME) compounds were identified by gas chromatograph-mass spectroscopy (GC–MS) analysis and major compounds viz., linolenic acid (C18:2), oleic acid (C18:2), stearic acid (C18:0), palmitic acids (C16:1), and myristic acid (C14:0). The produced bioethanol was confirmed using high-performance liquid chromatography (HPLC). Graphical abstract