A new combined approach to improved lipid production using a strictly aerobic and oleaginous yeast

Microbial lipids have potential applications in energy, and food industry, because most of those lipids are triacylglycerol with long-chain fatty-acids that are comparable to conventional vegetable oils and can be obtained without arable land requirement. Rhodosporidium toruloides is a strictly aerobic strain, where oxygen plays a crucial role in growth, maintenance, and metabolite production, such as lipids and carotenoids. Dissolved oxygen concentration is one of the major factors affecting yeast physiological and biochemical characteristics. In this context, different approaches have been developed to increase available oxygen by the increasing the aeration and the addition of an oxygen-vector. The growth of R. toruloides in 2-L mechanical stirred tank reactor equipped with 1 or 2 porous spargers and a 70 C/N ratio, revealed a lipid content of 0.47 and 0.52 g/g and a lipidic productivity of 0.16 and 0.17 g/L day, respectively. The oxygen-vector addition, increased the lipidic productivity for 0.20 g/L day and a lipid contend of 0.51 g of lipids/g of biomass. The combined approach, combining high aeration (AA), and 1% of n-dodecane addition (DA), produced a significant improvement in the lipid accumulation (62%, w/w), when compared with the DA (51%, w/w) and the AA (52%, w/w) approaches. The increasing of lipids accumulation and smaller culture time are key factors for the success of scale-up and profitability of a bioprocess.