Physiological Traits of Dihomo-γ-Linolenic Acid Production of the Engineered Aspergillus oryzae by Comparing Mathematical Models

Abstract

Dihomo-γ-linolenic acid (DGLA; C20:3 n-6) is expected to dominate the functional ingredients market for its role in anti-inflammation and anti-proliferation. The DGLA production by the engineered strain of Aspergillus oryzae with overexpressing Pythium 6-desaturase and 6-elongase genes was investigated by manipulating the nutrient and fermentation regimes. Of the nitrogen sources tested, the maximum biomass and DGLA titers were obtained in the cultures using NaNO 3 grown at pH 6.0. For establishing economically feasible process of DGLA production, the cost-effective medium was developed by using cassava starch hydrolysate (CSH) and NaNO 3 as carbon and nitrogen sources, respectively. The supplementation with 1% (v/v) mother liquor (ML) into the CSH medium promoted the specific yield of DGLA production (Y DGLA/X) comparable with the culture grown in the defined NaNO 3 medium, and the DGLA proportion was over 22% in total fatty acid (TFA). Besides, the GLA was also generated at a similar proportion (about 25% in TFA). The mathematical models of the cultures grown in the defined NaNO 3 and CSH/ML media were generated, describing that the lipid and DGLA were growth-associated metabolites corresponding to the relevant kinetic parameters of fermentations. The controlled mode of submerged fermentation of the engineered strain was explored for governing the PUFA biosynthesis and lipid-accumulating process in relation to the biomass production. This study provides an informative perspective in the n-6 fatty acid production through physiological manipulation, thus leading to a prospect in viable production of the DGLA-enriched oil by the engineered strain.

Metabolic Regulation of Sugar Assimilation for Lipid Production in Aspergillus oryzae BCC7051 through Comparative Transcriptome Perspective

“…It is a nonaflatoxin producing strain rendering superior growth performance over other microbial platforms in terms of cell robustness to surrounding environments and existing substrates [2,3]. The accumulative genome datasets of A. oryzae strains (https://www.ncbi.nlm.nih.gov/genome/?term=Aspergillus; accessed on 2 April 2021) have permitted significant progress in both fundamental and applied research [4][5][6][7][8]. Apart from the enzyme, amino acid, and organic acid production, A. oryzae has also been recognized as an oleaginous strain with capability in lipid production [9].…”

“…Apart from the enzyme, amino acid, and organic acid production, A. oryzae has also been recognized as an oleaginous strain with capability in lipid production [9]. Several studies demonstrated that A. oryzae has a potential as a cell chassis for production of n-6 polyunsaturated fatty acids (PUFAs) by engineering fatty acid and lipid biosynthetic pathways, thus yielding γ-linolenic and dihomo-γ-linolenic acids [8,10,11].…”