Lipid production by oleaginous microorganisms via co-fermentation of glucose and xylose derived from lignocellulosic feedstock

Studies on microbial lipids produced from a variety of non-edible feedstocks have recently drawn considerable attention because such production avoids the competition between foodstuffs and biofuels. In this study, we investigated the production of microbial lipids by several oleaginous microorganisms using low-cost sugars, which are derived from lignocellulosic feedstocks. Several microorganisms and culture media were tested and compared for lipid production using lignocellulosic feedstock-derived sugars (glucose and xylose) in flask cultures. The effect of the oxygen saturation rate on cell growth rate, carbon conversion efficiency, and lipid productivity was studied in fermentors. The oxygen utilization rate (OUR) and carbon dioxide evolution rate (CER) were also explored under different culture conditions. The cell growth rate and lipid yield were improved by using different culture modes and feeding strategies. A dry cell weight of 50 g/L, lipid productivity of 0.3 g/L/h, and lipid content of 58% were achieved using improved culture conditions. The fatty acids from these cultures were predominantly palmitic acid (C16:0), stearic acid (C18:0), and oleic acid (C18:1), corresponding with soybean oil and rapeseed oil. The current study has shown that lignocellulosic feedstock-derived sugars are suitable carbon sources for producing microbial lipids, which are precursors for biodiesel production.