Abstract
Microalgae with high oil productivities are most desired in biodiesel production. Chlorella lewinii SUB3545914, was isolated and assessed for its growth rates, lipid productivities and fatty acid profiles under heterotrophic cultivation. The alga was isolated after enrichment in BG-11 medium (pH = 7.3) under a light intensity of approximately 17.5 μE·m-2·s-1 at 30°C ± 2°C. In addition to morphology, polymerase chain reaction (PCR) and metagenomics were used for isolate identification. The DNA was sequenced and multiple sequence alignment of the BLASTED results revealed 95% similarity to Chlorella lewinii. Maximum growth (3.15 ± 0.06 g·L-1), lipid content (44.0%) and lipid volumetric productivities (118.80 ± 3.02 mg·L-1·day-1) in glucose supplemented media were more appreciable in comparison with the glycerol counterparts. Similarly, the highest growth (2.03 ± 0.68 g·L-1), lipid content (31.47%) and lipid productivities (47.21 ± 2.08 mg·L-1·day-1) in glycerol supplemented media were more than those got under autotrophic cultivation. Chlorophyll contents did not vary remarkably in heterotrophic cultures. The major fatty acids obtained by Gas Chromatography Mass Spectrometry (GC-MS) were oleic and Octadecanoic acids for all the culture conditions. Chlorella lewinii is appropriate for accumulating lipids for biodiesel under heterotrophic cultivation on glucose because of high lipid volumetric productivities.
Highlights
The demand for petroleum products is increasing because of the rising world population and industrialization
The biomass concentrations obtained in heterotrophic cultures with glucose
Liang et al [31] had previously observed that glucose utilisation by microalgae is dose-dependent, and the microalga Chlorella protothecoides showed that certain concentrations of medium glucose in mixotrophic culture condition may improve growth whereas increased glucose in the medium to up to 10% became inhibitory to the algal growth
Summary
The demand for petroleum products is increasing because of the rising world population and industrialization. Petro-diesel is currently cheaper than biodiesel, the interest in the development of technologies for the production of biodiesel has been on the increase due to its production from renewable biological sources. It is ecologically friendly, releasing comparatively very little carbon monoxide, much less hydrocarbons particulate matter (HPM) and no sulfur and aromatic compounds to the environment during combustion [1]. A major demerit of the use of this oil is that biodiesel produced from vegetable oils is usually expensive. Isolation of a good oil-producing species is critical in biodiesel production
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