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

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

doi:10.3389/fmicb.2020.546230

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 Δ6-desaturase and Δ6-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 NaNO3 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 NaNO3 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 (YDGLA/X) comparable with the culture grown in the defined NaNO3 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 NaNO3 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.

Highlights

Increasing concern on health and well-being by global consumers has stimulated the holistic process development in production of functional ingredients for creation of specialty and healthier products
This work aimed to investigate the physiological control of the engineered A. oryzae strain with overexpressing the Pythium 6desaturase and 6-elongase genes for DGLA production
DGLA Production Yield of the Engineered A. oryzae Strain Depending on Nitrogen Sources

Summary

Introduction

Increasing concern on health and well-being by global consumers has stimulated the holistic process development in production of functional ingredients for creation of specialty and healthier products. Dihomo-γ-Linolenic Acid Production in the Engineered A. oryzae in n-3 and n-6 series are attracting attention because of their physiological and structural roles in such biological systems. Dihomo-γ-linolenic acid (DGLA; C20:3 n-6) is a direct fatty acid precursor for biosynthesis of biologically active eicosanoids (1-series prostaglandin and thromboxanes) and other metabolites, which exert clinical efficacies, such as antiinflammatory (Nakamura et al, 1993), anti-thrombotic (Smith et al, 1989), anti-hypertensive (Hassall and Kirtland, 1984), and anti-allergic (Taki et al, 1993) activities (Tabolacci et al, 2010; Wang et al, 2012; Sergeant et al, 2016). The process development of DGLA production is required to meet the projected growing demands. Because of the fact that the 20-carbon PUFA is not generally found in common foods, it is important to overcome such constraint through biotechnological production using emerging tools and technologies

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