P106: Identifying the fatty acids elongation and desaturation system in Ashbya gossypii: towards single cell oil production

Fatty acid derivatives are highly relevant compounds in industry since they have found a wide range of applications, ranging from biofuels to fine chemicals. Metabolic engineering of microorganisms to produce “Single Cell Oils” (SCOs) seems to be a feasible strategy, with promising industrial results. Ashbya gossypii is an industry-friendly fungus that is known to accumulate large amounts of oils and whose scaling up and industrial exploitation have been strongly proven by its use in several production processes. These features point to A. gossypii as a good candidate for SCO production. Two kinds of enzymes: elongases and desaturases are the major determinants of lipid profiles. Two elongases (AgElo624 and AgElo586) and one desaturase (AgDes589) from A. gossypii were identified and characterized by heterologous expression in yeast. The results revealed that AgDes589 encodes a D12 desaturase able to produce linoleic acid (18:2) from oleic acid (18:1). AgElo624 encodes a long chain elongase that mainly elongates 18:0 to 20:0 and 22:0, and AgElo586 encodes a very long chain elongase able to use 18:0, 20:0 or 22:0 to produce 24:0 and 26:0. RT-PCR experiments indicated that whereas elongases are positively regulated in the presence of exogenous oils, the D12 desaturase appeared to be negatively regulated by end-products. In addition to Fatty Acid Synthase and two D9 desaturases, these three activities can accurately explain the whole fatty acid profile of this fungus, establishing a basis for future metabolic engineering approaches to produce high-value SCOs.