Abstract
Oleaginous fungi have recently gained increasing attention among different microorganisms due to their ability for lipid production for the preparation of biofuel. In the present study, a locally isolated fungus E45, identified genetically as Aspergillus sp. strain EM2018, was found to produce 25.2% of the total lipids content of its dry cell weight (DCW). Optimization of culture conditions was performed and lipid accumulation increased by about 2.4 fold (from 25.2% to 60.1% of DCW) when the fungus was grown for seven days in the potato dextrose (50 g/L) liquid medium at pH 5.0, incubation temperature at 30 ºC and inoculum size of 2 × 106 spore/mL. Supplementation of the medium with yeast extract and NaNO3 at a concentration of 0.05% as organic and inorganic nitrogen sources, respectively, increased lipid production (53.3% lipid/dry biomass). Gas chromatography analysis of fungal lipids revealed the presence of saturated (mainly palmitic acid C16:0 (33%) and lignoceric acid C24:0 (15%)) and unsaturated fatty acids in different proportions (mainly linoleic acid C18:2 (24.4%), oleica cid C18:1 (14%) and arachidonic C20:4 (7.4%). These findings suggest this new oleaginous fungus as a promising feedstock for various industrial applications and for the preparation of biodiesel.
Highlights
ChemicalsPotato dextrose liquid (PDL) and potato dextrose agar (PDA) media were purchased from Liofilchem Bacteriology products (Italy)
Aflatoxin test for the selected strain was performed by using the High Performance Liquid Chromatography (HPLC) technique according to the Association of Official Analytical Chemist (AOAC, 2000) as follows: Two hundred Medium vol (mL) of hexane were added to the cleanup dry films of the standard and test samples followed by adding 50 mL of trifluoroacetic acid (TFA) and mixing vigorously in the vortex mixer for 30 sec
A sample of 0.5 mL was dissolved in 1 mL of toluene in a flask fitted to a condenser, sulfuric acid (1%) in methanol (2.0 mL) was added and the mixture was refluxed for 7 h at 50 °C. 5 mL of 5% NaCl was added and the required esters were extracted with hexane (2 mL hexane for each 5 mL of the previous mixture)
Summary
Potato dextrose liquid (PDL) and potato dextrose agar (PDA) media were purchased from Liofilchem Bacteriology products (Italy). Vanillin was purchased from SD Fine Chem Limited (Mumbai, India). The chemicals and organic solvents used throughout the work were purchased from Sigma-Aldrich (St. Louis, MO, USA). Olive oil was bought from a local hypermarket (Cairo, Egypt)
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