Abstract
A novel recombinant strain has been constructed for converting glycerol into a specific conjugated linoleic acid isomer (trans-10, cis-12 CLA) using Yarrowia lipolytica as host. The lipid accumulation pathway was modified for increasing lipid content. Overexpression of the diacylglycerol transferase (DGA1) gene improved the intracellular lipid yield by approximately 45% as compared to the original strain. The corresponding intracellular lipid yield of recombinant strain WXYL037 reached 52.2% of the cell dry weight. In combination with integration of Δ12 desaturase from Mortierella alpina (MA12D) and DGA1, the linoleic acid (LA) production content reached 0.88 g/L, which was 2-fold that of the original strain. Furthermore, with overexpressed DGA1, MA12D and Propionibacterium acnes isomerase (PAI), the titer of trans-10, cis-12 CLA in WXYL037 reached 110.6 mg/L after 72 h of shake flask culture, representing a 201.8% improvement when compared with that attained in the WXYL030 strain, which manifested overexpressed PAI. With optimal medium, the maximum CLA content and lipid yield of Y. lipolytica Po1g were 132.6 mg/L and 2.58 g/L, respectively. This is the first report of the production of trans-10, cis-12 CLA by the oleaginous yeast Y. lipolytica using glycerol as the sole carbon source through expression of DGA1 combined with MA12D and PAI.
Highlights
Linoleic acid (LA, 18:2) and conjugated linoleic acid (CLA) have been attracting significant attention due to their potential health benefits, such as protection against carcinogenesis, reduction of atherosclerosis lesions, body fat modulation, anti hypercholesterolemic effects, and immunity enhancement with simultaneous attenuation of inflammation [1,2,3,4]
Content and lipid yield of Y. lipolytica Po1g were 132.6 mg/L and 2.58 g/L, respectively. This is the first report of the production of trans-10, cis-12 CLA by the oleaginous yeast Y. lipolytica using glycerol as the sole carbon source through expression of DGA1 combined with MA12D and Propionibacterium acnes isomerase (PAI)
The use of the oleaginous yeast Y. lipolytica benefits from its well-developed tools for engineering the lipid metabolic pathway, and this species can transform inexpensive raw glycerol derived from biodiesel production into high-value products such as CLA
Summary
Linoleic acid (LA, 18:2) and conjugated linoleic acid (CLA) have been attracting significant attention due to their potential health benefits, such as protection against carcinogenesis, reduction of atherosclerosis lesions, body fat modulation, anti hypercholesterolemic effects, and immunity enhancement with simultaneous attenuation of inflammation [1,2,3,4]. The use of the oleaginous yeast Y. lipolytica benefits from its well-developed tools for engineering the lipid metabolic pathway, and this species can transform inexpensive raw glycerol derived from biodiesel production into high-value products such as CLA. The TAG accumulated in cells can be further hydrolyzed into glycerol and free fatty acids (FFA) by endogenous lipases to provide raw materials for the synthesis of additional products while providing energy for cell growth [23]. In order to further improve the contents of lipid and CLA in Y. lipolytica from non-oil substrates, the copy numbers of pivotal genes, GPD1 or DGA1, were increased, this provides an enhanced driving force towards production of lipid. Raw glycerol was utilized as carbon source to overproduce CLA in Y. lipolytica by modifying the lipid accumulation pathway and heterologously expressing MA12D and PAI
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