Enhancing biomass and lipid productivity in Chlorella vulgaris through CPPU-mediated growth and photosynthetic regulation

Chlorella vulgaris has recently garnered attention due to its biofuel potential, along with its promising growth rate. However, the development of feasible strategies to enhance oleaginicity and biomass simultaneously in C. vulgaris is receiving considerable interest. Amongst, supplementing suitable chemical modulators has emerged as an effective tool. Here, we assessed the impact of CPPU (forchlorfenuron), a synthetic phytohormone on regulating microalgal growth and metabolic characteristics. We showed that the CPPU provision strongly enhances algal growth, photosynthetic efficiency, and lipid accumulation under standard conditions, with dosages ranging from 0 to 6 mg/L which shows a clear dose-dependent response. CPPU markedly enhanced photosynthetic performance, biomass, and specific growth rate, especially at 4 mg/L and 6 mg/L dosages. Cell density was measured by direct cell count method which was initially increased at these optimal concentrations, and biomass content was increased by 2-fold. Simultaneously, a noteworthy increase in photosynthetic efficiency and quantum yield (Fv/Fm) in the order of 22 units and 0.67 was evidenced. CPPU increases lipid content and photosynthetic genes (psaB, psbC, and rbcL) at optimum concentration 4 mg/L, highlighting the photosynthetic efficiency. Notably, total lipid content was increased by 2.4-fold in the CPPU-treated cells than that of the control cells. Collectively, our results indicate that CPPU is a promising additive to boost algal biofuel yields by simultaneously raising growth rate and lipid production.