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

Xiuwen Wang; Junhuan Yang; Hassan Mohamed; Aabid Manzoor Shah; Shaoqi Li; Shuxian Pang; Chen Wu; Futing Xue; Wenyue Shi; Beenish Sadaqat; Yuanda Song

doi:10.3389/fmicb.2022.1078157

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

Front Microbiol. 2022 Dec 15:13:1078157. doi: 10.3389/fmicb.2022.1078157. eCollection 2022.

Authors

Affiliations

¹ Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, China.
² Department of Food Sciences, College of Food Science and Engineering, Lingnan Normal University, Zhanjiang, China.
³ Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Assiut, Egypt.

Abstract

Mucor circinelloides WJ11, an oleaginous filamentous fungus, produces 36% lipid of its cell dry weight when cultured in a high C/N ratio medium, however, the yield of γ-linolenic acid (GLA) is insufficient to make it competitive with other plant sources. To increase the GLA content in M. circinelloides WJ11, this fungus was engineered by overexpression of its key genes such as Δ6-, Δ12-, and Δ9-desaturases involved in GLA production. Firstly, we tried to overexpress two Δ6-desaturase isozymes to determine which one played important role in GLA synthesis. Secondly, Δ6-and Δ12-desaturase were co-overexpressed to check whether linoleic acid (LA), the precursor for GLA synthesis, is a limiting factor or not. Moreover, we tried to explore the effects of simultaneous overexpression of Δ6-, Δ12-, and Δ9-desaturases on GLA production. Our results showed that overexpression (1 gene) of DES61 promoted higher GLA content (21% of total fatty acids) while co-overexpressing (2 genes) DES61 and DES12 and simultaneous overexpressing (3 genes) DES61, DES12, and DES91 increased the GLA production of engineered strains by 1.5 folds and 1.9 folds compared to the control strain, respectively. This study provided more insights into GLA biosynthesis in oleaginous fungi and laid a foundation for further increase in GLA production into fungus such as M. circinelloides.

Keywords: GLA production; Mucor circinelloides; co-overexpression; desaturases; homologous recombination.