Influence of nutrient deprivations on lipid accumulation in a dominant indigenous microalga Chlorella sp., BUM11008: Evaluation for biodiesel production

Microalgae are a potential source of biodiesel. The urgent need for an alternative and sustainable energy has created renewed interest to analyze the microalgae for biodiesel production. In this study, a dominant indigenous freshwater unicellular microalgal strain Chlorella sp., BUM11008, was examined for its efficiency towards biodiesel production. The organism was evaluated for ability to yield high of biomass and lipid productivity under normal and various nutrient-deprived conditions (nitrogen, phosphate-potassium, iron, and all three combined). Under normal conditions, after 20 days of cultivation in Chu10 medium, the organism yielded a biomass of 2.58 ± 0.07 g/L, with lipid content of 312.16 ± 2.38 mg/g. In a two-phase culturing system upon nutrition deprivation, the organism was able to respond with different levels of lipid accumulation. Among the various post-harvest treatments, nitrogen deprivation yielded the highest lipid productivity of 53.96 ± 0.63 mg/L d, followed by the combined deprivation condition (49.16 ± 1.36 mg/L d). FAME profiles of the isolate were found to meet the requirements of international standards for biodiesel. The study leads to the conclusion that the two-phase culturing system with nitrogen starvation as post-harvest treatment would be suitable for gaining maximum biomass productivity, and lipid content of high quality fatty acids. Thus, it is proposed that Chlorella sp., BUM11008, would be a promising candidate for sustainable biodiesel production.

► The present study highlights the need for an indigenous microalga for biodiesel production.
► We focused on two-phase culturing system, with four different post-harvest treatments as stress.
► Increased lipid accumulation in Chlorella sp. under nitrogen-deprived condition is documented.