Reengineering lipid biosynthetic pathways of Aspergillus oryzae for enhanced production of γ-linolenic acid and dihomo-γ-linolenic acid

• Main Authors: Sukanya Jeennor, Jutamas Anantayanon, Sarocha Panchanawaporn, Sakda Khoomrung, Chanikul Chutrakul, Kobkul Laoteng
• Other Authors: Thailand National Center for Genetic Engineering and Biotechnology
• Format: Article
• Published: 2020
• Subjects: Biochemistry, Genetics and Molecular Biology
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/50124
• Institution: Mahidol University

© 2019 Elsevier B.V. Biological significance of 18-carbon polyunsaturated fatty acids, γ-linolenic acid (GLA; C18:3 n-6)and dihomo-γ-linolenic acid (DGLA; C20:3 n-6)has gained much attention in the systematic development of optimized strains for industrial applications. In this work, a n-6 PUFAs-producing strain of Aspergillus oryzae was generated by manipulating metabolic reactions in fatty acid modification and triacylglycerol biosynthesis. The codon-optimized genes coding for Δ6-desaturase and Δ6-elongase of Pythium sp., and diacylglycerol acyltransferase 2 (mMaDGAT2)of Mortierella alpina were co-transformed in a single vector into A. oryzae BCC14614, yielding strain TD6E6-DGAT2. Comparative phenotypic analysis showed that a 70% increase of lipid titer was found in the engineered strain, which was a result of a significant increase in triacylglycerol (TAG)content (52.0 ± 1.8% of total lipids), and corresponded to the increased size of lipid particles observed in the fungal cells. Interestingly, the proportions of GLA and DGLA in neutral lipids of the engineered strain were similar, with the highest titers obtained in the high C:N culture (29:0; 6% glucose)during the lipid-accumulating stage of growth. Time-course expression analysis of the engineered strain revealed transcriptional control of TAG biosynthesis through a co-operation between the native DGAT2 of A. oryzae and the transformed mMaDGAT2.