Expression of Vitreoscilla hemoglobin enhances production of arachidonic acid and lipids in Mortierella alpina

• Published in: BMC biotechnology Vol. 17; no. 1; p. 68
• Main Authors: Zhang, Huidan, Feng, Yingang, Cui, Qiu, Song, Xiaojin
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 30.08.2017; BioMed Central; BMC
• Subjects: Acid production; Arachidonic acid; Arachidonic Acid - genetics; Arachidonic Acid - metabolism; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bioreactors; Cell growth; Cell morphology; Constraining; Cytology; Dissolved oxygen; Efficiency; Fatty acids; Fatty Acids - genetics; Fatty Acids - metabolism; Fermentation; Fungi; Gene expression; Genetic aspects; Genetic transformation; Glucose; Hemoglobin; Hemoglobins; Industrial Microbiology - instrumentation; Industrial Microbiology - methods; Lipid Metabolism; Lipids; Metabolism; Metabolites; Morphology; Mortierella - genetics; Mortierella - growth & development; Mortierella - metabolism; Mortierella Alpina; Observations; Oxygen; Oxygen consumption (Metabolism); Petroleum production; Plasmids; Polyunsaturated fatty acids; Properties; Proteins; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Software; Truncated Hemoglobins - genetics; Truncated Hemoglobins - metabolism; Utilization; Zygomycetes; Hemoglobin; Arachidonic acid; Dissolved oxygen; Fermentation; Mortierella Alpina
• ISSN: 1472-6750; 1472-6750
• DOI: 10.1186/s12896-017-0388-8

Arachidonic acid (ARA, C20:4, n-6), which belongs to the omega-6 series of polyunsaturated fatty acids and has a variety of biological activities, is commercially produced in Mortierella alpina. Dissolved oxygen or oxygen utilization efficiency is a critical factor for Mortierella alpina growth and arachidonic acid production in large-scale fermentation. Overexpression of the Vitreoscilla hemoglobin gene is thought to significantly increase the oxygen utilization efficiency of the cells. An optimized Vitreoscilla hemoglobin (VHb) gene was introduced into Mortierella alpina via Agrobacterium tumefaciens-mediated transformation. Compared with the parent strain, the VHb-expressing strain, termed VHb-20, grew faster under both limiting and non-limiting oxygen conditions and exhibited dramatic changes in cell morphology. Furthermore, VHb-20 produced 4- and 8-fold higher total lipid and ARA yields than those of the wild-type strain under a microaerobic environment. Furthermore, ARA production of VHb-20 was also 1.6-fold higher than that of the wild type under normal conditions. The results demonstrated that DO utilization was significantly increased by expressing the VHb gene in Mortierella alpina. The expression of VHb enhances ARA and lipid production under both lower and normal dissolved oxygen conditions. This study provides a novel strategy and an engineered strain for the cost-efficient production of ARA.