AUTHOR=Antimanon Sompot , Anantayanon Jutamas , Wannawilai Siwaporn , Khongto Bhimabol , Laoteng Kobkul 

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

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.546230

DOI=10.3389/fmicb.2020.546230

ISSN=1664-302X

ABSTRACT=<p>Dihomo-γ-linolenic acid (DGLA; C20:3 <italic>n</italic>-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 <italic>Aspergillus oryzae</italic> with overexpressing <italic>Pythium</italic> Δ<sup>6</sup>-desaturase and Δ<sup>6</sup>-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<sub>3</sub> 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<sub>3</sub> as carbon and nitrogen sources, respectively. The supplementation with 1% (<italic>v</italic>/<italic>v</italic>) mother liquor (ML) into the CSH medium promoted the specific yield of DGLA production (<italic>Y<sub><italic>DGLA</italic></sub><sub>/</sub><sub><italic>X</italic></sub></italic>) comparable with the culture grown in the defined NaNO<sub>3</sub> 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<sub>3</sub> 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 <italic>n-</italic>6 fatty acid production through physiological manipulation, thus leading to a prospect in viable production of the DGLA-enriched oil by the engineered strain.</p>