Insights into lipid accumulation features of Coccomyxa sp. IITRSTKM4 under nutrient limitation regimes

Abstract

Microalgal lipids are deemed to be the most promising alternative to petroleum fuels, enduring the pressure of fuel scarcity. Screening oleaginous microalgae from natural habitats are imperative, as novel strains producing enhanced biofuel components can make them economically viable. The present investigation involves the isolation and characterization of a novel microalga Coccomyxa sp. IITRSTKM4, under nitrogen (N)-, phosphorus (P)-, and sulfur (S)- limitation The reduction in biomass and chlorophyll content of nutrient-starved cells was compensated with stable PSII efficiency and enhanced cellular lipid content. The maximum lipid content ( ∼ 41 %) and lipid productivity (22 ± 2.2 mg/L/d) were achieved under N-deficiency and synergistic NPS-limitation, respectively. However, S-deficient cells resulted in increased carbohydrate content ( ∼ 33%). Further, analysis of biochemical components suggested that protein pools were diverted towards the synthesis of storage molecules (lipid/carbohydrate), aiding cell survival under nutrient starvation. FAME profiling of obtained lipid indicated that it majorly contains C16–C18 fatty acids. The estimated biodiesel quality index parameters have complied with the American (ASTM D6751) and European (EN 14214) standards, thus establishing Coccomyxa sp. IITRSTKM4 a suitable candidate for biodiesel production. Moreover, the production of lipid and carbohydrate under N- and S-deficiency evidences the versatility of the strain for producing biofuels. • Novel oleaginous microalgal strain isolated from water of Ganga Ghat, Haridwar. • Lipid accumulation under different nutrient regimes was investigated. • N/P deficiency improved lipid, whereas S-deficiency increased carbohydrate content. • Maximum lipid productivity was achieved in synergistic N/P/S-limitation. • Biodiesel properties complied with international fuel standards.