Direct transesterification of fatty acids produced by Fusarium solani for biodiesel production: Effect of carbon and nitrogen on lipid accumulation in the fungal biomass.

The present work aims to explore a new oleaginous Fusarium isolate potential to accumulate lipids in its biomass from inexpensive substrates. In addition, impacts of crabon and nitrogen sourses and their ratios on lipid production by the interested fungal isolate were also conducted.

Lipid was assayed by sulfo-phosphor-vanillin (SPV) colorimetric method. Among eleven Fusarium isolates obtained onto potato dextrose agar (PDA) from rhizosphereic soils, Fusarium RAS18 was selected as the highest producer that accumulates above 20 % lipid. It was identified based on phenotypic characterization and the Internal Transcribed Spacer (ITS) sequence as Fusarium solani, that was recorded in the GenBank database under the accession number MK167372.1. The optimized lipids yield (34·5 %) is obtained on glycerol (35 gl^-1 ) and peptone (1·5 gl^-1 ) as carbon and nitrogen sources, respectively. The produced fatty acid methyl esters (biodiesel) is composed of linoleic acid (56·81%), palmitic acid (17·81%), oleic acid (11·81%) and stearic acid (11·12). The unsaturated fatty acids accounted 69% and this is nearly similar to the plant oils commonly used in biodiesel production.

These findings suggest the applicability of Fusarium solani RAS18 as a promising strain to accumulate lipids from glycerol as a feedstock for biodiesel production.

Fusarium solani RAS18 is a new oleaginous fungal isolate that is able to produce lipid (34·5 %, gg^-1 ) from glycerol. Glycerol is a cheap substrate and is formed as a byproduct from transesterification process and others industries. Thus, recyclation of glycerol for lipid production by microorganisms is an important point of economic view. Direct transesterification of the produced fatty acids indicated its similarity to the plant oil composition that used in biodiesel production. So, F. solani RAS18 might be a potential tool for lipid as a feedstock for biodiesel production.