| Microbial lipids can be produced by the oleaginous yeast Lipomyces starkeyi from a wide range of carbohydrates, including hexose and pentose sugars. The main barrier for commercial production of microbial lipids is their production costs. The major cost contributing factors in production of microbial lipids are the medium components, processing, and lipid recovery from cells. Medium cost comprises of carbon substrate and other essential nutrients, mainly phosphate. The carbohydrate costs can be reduced by using lignocellulosic materials as feedstocks. But the process of extraction of sugars from lignocellulosic materials produces toxic byproducts. The effect of byproducts, such as furfural, 5-hydroxy methyl furfural (HMF), vanillin, para hydroxy benzaldehyde (PHB), and syringaldehyde, were examined for cell growth and lipid production by Lipomyces starkeyi. The inhibitory effects of these byproducts were not significant in all cases up to 500 mg/L of inhibitors in fermenting media. Under the phosphate optimization, phosphate concentration corresponding to 1/20-X was found optimal and the medium cost can be reduced from $9.34 per gallon lipid to $3.11 per gallon lipid. For extraction of lipid, methyl tertiary butyl ether-methanol solvent system showed better potential than other solvents studied in lipid extraction from the economical view point. |
