Microbial Oil Derived from Filamentous Cyanobacterium Trichormus sp. as Feedstock to Yield Fatty Acid Ethyl Esters by Enzymatic Synthesis

The aim of this study was to optimize the cultivation conditions of Trichormus sp. CENA77 and to evaluate the lipid feedstock to generate ethyl esters via enzymatic route using NovozymÒ 435 as catalyst. Under optimized cultivation conditions (1.5 g L-1 Na2CO3 and 150 µmol photon m−2s−1 light intensity), biomass productivity of 286.5 ± 3.6 mg.L−1.day−1, lipid contents of 14.5 ± 2.8% and lipid productivity of 41.5 ± 0.4 mg.L−1day−1 were achieved. Enzymatic transesterification was performed in a microwave reactor using a 1:12 molar ratio (oil/ethanol) at 50°C assessing iso-octane as solvent for 12 h. The viscosity values for the microbial oil (51.9 mm2.s-1) sharply decreased to 10.7 mm2s-1, upon the progress of transesterification reaction. The maximum fatty acid ethyl esters yield (80%) achieved was due to the presence of non-lipid compounds, which may have affected the biocatalyst activity. Evidence of the Novozym® 435 deactivation was demonstrated by the assistance of Fourier transform infrared spectroscopy and scanning electron microscopy analyses.