Abstract

Biodiesel is an alternative renewable fuel and its production rises rapidly. Microbial oils produced by oleaginous microorganisms can be used as a feedstock for biodiesel production so as to sustain the increasing demand for biodiesel and alleviate the competition with the food supply. This study investigated oil production by an oleaginous fungus, Mortierella sp., which was isolated from soils of Tamil Nadu in India. The flask culturing experiment shows that the optimal lipid production conditions were glucose as the carbon source (0.16 M), yeast extract (one percent) as the nitrogen source, temperature at 30°C and pH of 6.5. Under the optimal conditions, the oil production potential of ortierella sp was examined in a three-litre pilot-scale fermentor. The fungus accumulated 44.1% of lipids in dry biomass and the biomass growth was 15.9 g l^-1. The fungal oil contained oleic acid of 38.2%, stearic acid of 11.5%, linolenic acid of 4.8% and palmitic acid of 19.6%, and its fatty acid composition was similar to that of vegetable oils. The crude oil had properties: density of 920 Kg/m³ at 15°C, viscosity of 54.81 mm² /s at 40°C, flash point of 218°C, pour point of 7.0°C, water content of 3.9%, ash content, 0.62%, carbon residue of 0.082%, acid value of 28.22 Mg KOH/g, calorific value of 32.05 MJ/Kg, free fatty acid of 14.55, and fire point of 230°C. The oil properties were much similar to Jatropha oil and rapeseed oil.  

Key words: Biodiesel, microbial oil, Mortierella sp, oleaginous fungi.