Isolation of microalgae species from arid environments and evaluation of their potentials for biodiesel production

Abstract

Twenty-five (25) strains of microalgae were isolated and screened for growth, lipid accumulation and biodiesel production from arid environments of North East Nigeria. Isolates that produced biomass concentration (≥ 1.50 g L^-1 cell dry weight), accumulated high concentrations of lipids (≥ 18% of the cell biomass) and could be purified on agar plates were selected for further studies. Four strains morphologically identified as Oocystis IA1, Chlorella IA7, Chlorococcum KA9 and Botyrococcus YA5 were selected. The maximum biomass concentrations (g L^-1) and lipid contents (%) were 3.02, 3.92, 3.59 and 2.89, and 57, 67.23, 63 and 65 dry cell weights for Oocystis IA1, Chlorella IA7, Chlorococcum KA9 and Botyrococcus YA5, respectively. The highest oil productivities (mg L^-1 day^-1) were 135.28 ± 3.32 (Oocystis IA1), 165.22 ± 3.36 (Chlorella IA7), 131.76 ± 1.11 (Chlorococcum KA9) and 140.37 ± 2.13 (Botyrococcus YA5). Maximum chlorophyll contents (g g^-1 cell) were 34.97, 30.00, 39.71 and 32.27, respectively. Fatty acid methyl ester profiles indicated the presence of C16:0, C16:1, C18:0, C18:1, and C18:2. Oleic acid (C18: 1) was predominant, ranging between 73.3 and 85.6%. Biodiesel properties were within the ASTM standards. The present study suggested that the four isolates are good for biodiesel production.

Keywords: Biodiesel, Chlorella, Chlorococcum, Botyrococcus sp., lipid accumulation, microalgae, Oocystis.

Abbreviation: FAME, Fatty acids methyl esters.