Aim and Background: Micro-organisms that can accumulate lipid more than 20% of their biomass are called oleaginous. Microbial lipid has high similarity with plant's oil the only difference between them is that microbial lipids are rich in polyunsaturated fatty acids. Synthesized lipid by the yeast has potential of using in pharmaceutical industry for technical purposes or as nutritional supplements. The importance of microbial triacylglycerols is the high amount of polyunsaturated fatty acids with 16 and 18 atoms of carbon which is important from nutritional point of view.

Materials and Methods: In this study the amount of lipid production by standard and native yeast strain on glucose, xylose and glycerol as carbon sources was evaluated. After selection the type of carbon source, the effect of MgSO4 on lipid production was investigated by one factorial method. After these steps, optimization of other parameters such as carbon and nitrogen concentration, temperature, agitation rate, pH and time of incubation was done with Taguchi method. FTIR Spectroscopy was used for analysis and verification of produced oil, in this study.

Results: The yeasts Yarrowia lipolytica DSM70562 and geotrichum BL have reached to lipid production of 7.35 g/L and 5.35 g/L, respectively. The most effective factor in optimization process of evaluated yeasts was the concentration of carbon source. This factor for the evaluated standard and native yeasts strains was 41.37% and 63.57%, respectively. The results of lipid analysis by FTIR Spectroscopy technique showed remarkable similarity between extracted oil from yeast strains and related standard (triolein).

Conclusion: According to the results obtained by Taguchi design, lipid production in evaluated standard and native yeasts increased 2.94 g/L and 1.22 g/L, respectively after optimization. This shows the high efficiency of using Taguchi design in optimization of medium condition. So by using Taguchi design we can do the optimization process, which is the necessary and effective step of all industrial process for increasing productivity and reducing the costs, as best as possible.