M. Enshaeieh - Young Researchers and Elite Club, Falavarjan Branch, Islamic Azad University, Isfahan, Islamic Republic of Iran.
A. Abdoli - Young Researchers and Elite Club, Falavarjan Branch, Islamic Azad University, Isfahan, Islamic Republic of Iran.
M. Madani - Department of Microbiology, Falavarjan Branch, Islamic Azad University, Isfahan, Islamic Republic of Iran.

Microbial oil has high similarity to the oil obtained from plants and animals. They are renewable sources that can be used for different purposes such as production of biofuels. Biofuels are renewable, biodegradable, and nontoxic, which makes them highly environmentally friendly. Producing oil from yeasts has more advantages than that from plants. Accordingly, isolation of oleaginous yeasts with high ability of lipid production is highly valuable. A total of ۱۳۸ yeasts were isolated for the purpose of this study. From this amount, ۳۵ were capable of producing lipid. After extracting lipid, the best strain was selected and, by using PCR method, identified as Rhodotorula mucilaginosa. Optimization was done using the design of experiments; Qualitek-۴ (W۳۲b) software was used for analyzing the experimental data. According to the results, Rhodotorula mucilaginosa proved to comprise lipid, dry biomass, and lipid productivity at levels of ۱۰.۹۷ g L -۱, ۱۸.۸۴ g L-۱, and ۵۸.۲% in optimized conditions, respectively. Lipid content on corn stalk and wheat straw hydrolysate was ۳۶.۹ and ۴۱.۸%, respectively. The extracted lipid was analyzed by FTIR spectroscopy and gas chromatography-mass spectrometry (GC-MS). The study showed high potential of lipid production in Rhodotorula mucilaginosa and also high efficiency of using Taguchi design in optimization of medium condition; therefore, by using this method, the optimization process can be done as best as possible. The economic values of microbial lipid production become more favorable when waste materials with zero or negative economic value are utilized as carbon source. Using bioprocesses such as microbial lipid production from waste materials, the problem of shortage of energy resources, and also air pollutions caused by fossil fuels, could be eliminated.

Air pollution, Biofuels, Microbial lipid