Homologous and Heterologous Expression of Delta(12)-Desaturase in Mucor circinelloides Enhanced the Production of Linolenic Acid

Abstract

Linolenic acid (LA) is gaining more interest within the scientific community. This is because it has a potential medical role in reducing the risk of inflammation, carcinogenesis, atherosclerosis and diabetes and is a valuable nutraceutical for human health. The oleaginous fungus Mucor circinelloides produces a high lipid content (36%), including valuable polyunsaturated fatty acids (PUFAs). However, the critical step in which oleic acid (OA) is converted into LA is not efficient at supplying enough substrates for PUFA synthesis. Hence, we propose a method to increase LA production based on genetic engineering. The overexpression of the Δ12-desaturase gene from M. circinelloides and Mortierella alpina increased the LA content and improved the lipid accumulation (from 14.9% to 21.6% in the Δ12-desaturase gene of the M. circinelloides overexpressing strain (Mc-D12MC) and from 14.9% to 18.7% in the Δ12-desaturase gene of M. alpina overexpressing strain (Mc-D12MA)). Additionally, the up-regulated expression levels of these genes targeted the genes involved in NADPH production, implying that the elevated Δ12-desaturase gene may function as a critical regulator of NADPH and lipid synthesis in M. circinelloides. This study provides the first evidence to support the design of metabolic engineering related to LA and PUFA production in M. circinelloides for potential industrial applications.

Simultaneous overexpression of ∆6-, ∆12- and ∆9-desaturases enhanced the production of γ-linolenic acid in Mucor circinelloides WJ11

“…But in previous study, the co-expression of ∆6and ∆12-desaturase was not as effective as the single ∆6-desaturase expression (Zhang et al, 2017). In the present study, the dual overexpression had a higher total fatty acid content (31.7% of CDW) than the single overexpression of DES61 (24.7% of CDW) and DES12 (26.8% of CDW) (Yang et al, 2022), but less than the sum of both. The additional introduction of DES12 in the DES6-overexpressing strain did not increase GLA content (12.8%) compared with the control (13%).…”

“…In addition, wild-type strain WJ11 was able to accumulate OA (up to 37%), Yang et al enhanced LA content with OA content decreasing by overexpression ∆12-desaturase, which indicated that ∆12-desaturase was the rate-limiting step ( Yang et al, 2022 ). We predicted that co-overexpression of ∆6- and ∆12-desaturase would further elevate GLA production by increasing the production of precursor LA.…”