Biosynthesis, characterization and enzymatic transesterification of single cell oil of Mucor circinelloides – A sustainable pathway for biofuel production

• A Brazilian Mucor circinelloides strain was found to be a good SCO producer.
• The microwave-assisted EtOH extraction led to the best extraction of SCO.
• The SCO showed considerable amount of monounsaturated fatty acids.
• The enzymatic ethanolysis of the SCO achieved high yields of esters.
• Biodiesel properties from SCO are comparable with those from vegetable oils.

The filamentous fungus Mucor circinelloides URM 4182 was tested to determine its ability to produce single-cell oil suitable for obtaining biodiesel. Cell growth and lipid accumulation were investigated in a medium containing glucose as the main carbon source. A microwave-assisted ethanol extraction technique (microwave power ⩽200 W, 50–60 °C) was established and applied to lipid extraction from the fungal hyphae to obtain high lipid concentration (44%wt) of the dry biomass, which was considerably higher than the quantity obtained by classical solvent methods. The lipid profile showed a considerable amount of oleic acid (39.3%wt), palmitic acid (22.2%wt) and γ-linoleic acid (10.8%wt). Biodiesel was produced by transesterification of the single-cell oil with ethanol using a immobilized lipase from Candida antarctica (Novozym® 435) as the catalyst. 1H NMR and HPLC analyses confirmed conversion of 93% of the single-cell oil from M. circinelloides into ethyl esters (FAEE).

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