Lipid content and profile of Rhodotorula toruloides during fermentation

Abstract: Oleaginous yeast such as Rhodotorula toruloides is a promising organism for production of lipids from lignocellulosic substrates. Microbial lipids have potential applications in energy, food, feed and pharmaceutical industry, because most of the lipids are triglycerides with long chain fatty acids that are comparable to typical vegetable oils and can be obtained without arable land requirement. This study investigated lipid production in the batch cultivation over time by the yeast Rhodotorula toruloides. Furthermore, the composition of fatty acids and lipid classes were analyzed by using gas chromatography (GS) and thin layer chromatography (TLC), respectively. Under the batch cultivation over time, maximum lipid content 34% of the cell dry weight was obtained on the day 5 and 6. However, interestingly polyunsaturated fatty acid (PUFA), omega-3 fatty acid (n-3) and omega-6 fatty acid (n-6) compositions on day 6 is higher than day 5. Through analyzing of total lipid compositions and TAG analysis, the most abundant fatty acids are oleic acid (C18:1), palmitic acid (C16:0) and linoleic acid (C18:2), which are useful precursors for conversion to biofuel production. A higher n-6/n-3 ratio is observed during total lipid and triglyceride analysis, however, a lower ratio is advantageous in order to avoid negative impacts on human or animal health, if the oil is used for food or feed. The potentialities of lipids accumulation on shorter culture time and culture conditions are the key elements for the success of scale-up and profitability bioprocess.