Effect of photo-autotrophic cultural conditions on the biomass productivity and composition of Chlorella vulgaris

Abstract

The study aims to investigate the effect of photo-autotrophic cultural conditions on the productivity and biomass composition of Chlorella vulgaris. The following five photo-autotrophic cultural conditions were investigated: light intensity (4000, 10,500, 17,000, 23,000, 30,000 lux), temperature (25, 28, 32, 35, 40 °C), pH (6, 7, 8, 9, 10), CO₂ (0.03, 2.5, 5, 7.5, 10%) and NO₃⁻ (0, 250, 500, 750, 1000 mg/L). Results indicate that lipid and protein yields were increased by 3.19 fold and decreased by 1.47 fold, respectively, under NO₃⁻ deficiency (0 mg/L). Meanwhile, carbohydrate yield was increased by 1.39 fold in 5% CO₂. Further cultivation with parameters of the highest biomass productivity (10,500 lux, 28 °C, pH 8, 5% CO₂ and 500 mg/L NO₃⁻) achieved the maximum biomass productivity of 0.468 g/L/day. Moreover, cultivation with parameters of the highest lipid yield (23,500 lux, 40 °C, pH 8, 0.03% CO₂ and 0 mg/L NO₃⁻) achieved the maximum lipid yield of 43.70%. The major fatty acid methyl ester compositions produced were C20:0 (39.08%) and C16:0 (37.15%), producing biodiesel with high cetane number and oxidative stability. These promising results provide a comprehensive comparison regarding the effect of photo-autotrophic cultural conditions on microalgae biomass and its potential application as a biofuels feedstock.

Keywords:

• Chlorella vulgaris
• microalgae biomass
• lipid
• carbohydrate
• biofuel feedstock

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgements

The authors wish to thank The Ministry of Education Malaysia (MOE) for financing this study through the Fundamental Research Grant Scheme (Code: 2015-01611-102-02). We are also grateful to Makmal Pencirian Struktur Molekul (MPSM) at the Centre for Research and Instrumentation Management (CRIM), Universiti Kebangsaan Malaysia (UKM) for their technical assistance.