Two promoters of biodiesel and biomass production induced by different concentrations of myo-inositol in Chlorella vulgaris

Microalgae are a large group of phototrophic microorganisms that convert CO2 into biomass, which can be used as an important source of biofuels. Biofuels have a lot of interesting applications in various industries. The main objective of the current study was to assess the biomass and lipid production, gene expression of acetyl-CoA carboxylase (accD) and ribulose bisphosphate carboxylase large-chain (rbcL), and the lipid content produced by myo-inositol treatment in the microalga Chlorella vulgaris. Three different myo-inositol concentrations (i.e., 50, 100, and 200 mg/L) were added to the algal growth media, and the algal cells were sampled on the day of entering the stationary phase of the growth cycle. Biomass production was increased by increasing the supplement. However, the 200 mg/L concentration of myo-inositol was critical for lipid production. To evaluate the effect of the vitamin on the expression of the accD and rbcL genes, real-time PCR was used. The rbcL gene expression increased in relation to biomass production, i.e., 224.08 times higher than the control. On the other hand, the accD expression at 200 mg/L myo-inositol concentration, as physiological stress, increased, i.e., 95.2 times higher than the control. Therefore, this growth complement can induce biomass and lipid production. Findings of the present study provide valuable insight into determining the biochemical modulation strategies of biomass and lipid production. In this study, two separate controlling systems and two independent promoters were proposed to regulate the transcription of rbcL and accD genes induced by various concentrations of myo-inositol.