Chlorella vulgaris growth, pigment and lipid accumulation: effect of progressive light and hydrogen peroxide exposure

BACKGROUND Chlorella vulgaris is being explored for several applications such as biodiesel production, nutrient supplementation, animal feed and pharmaceutical products. In this study, the performance of a batch culture under progressive light intensity and the effect of hydrogen peroxide (H2O2) concentration on lipid accumulation were investigated. RESULTS Under progressive light intensity (60 to 300 mu mol m(-2) s(-1)), a 43% biomass increase was achieved in comparison with the control light conditions (60 mu mol m(-2) s(-1)), whereas a 300 mu mol m(-2) s(-1) light intensity caused growth inhibition to the culture. In addition, an increase in carotenoid content from 0.102 mg g(-1) biomass (control) to 0.460 mg g(-1) (progressive light) and lipid accumulation from 31.0 mg g(-1) (control) to 36.5 mg g(-1) (progressive light) was observed. However, the moderate illumination conditions (60 mu mol m(-2) s(-1)) induced a very significant increase of chlorophyll b, regarding the progressive light mode, increasing the photosynthetic efficiency. After the growth phase, the biomass was subjected to stress conditions by adding H2O2 to the culture medium at different concentrations: 0.75 mmol L-1 increased the lipid content of the biomass from 3.6% to 10.3% in a 3-day test, reaching lipid productivity of 70.4 mg L-1 day(-1), an increase of approximate to 40% compared to the phosphate starvatiod for the same culture time. CONCLUSION The progressive light system allowed an increase in biomass and lipid accumulation. Together with the exposure to H2O2, this work provides a new approach for lipid and pigment production from microalgae. (c) 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

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In this study, activated carbon fibers with high specific surface area were prepared from oyster shells, which showed excellent adsorption performance and cyclic regeneration ability.