초록
<P><B>Background</B></P><P>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 <I>Mortierella alpina</I>. Dissolved oxygen or oxygen utilization efficiency is a critical factor for <I>Mortierella alpina</I> growth and arachidonic acid production in large-scale fermentation. Overexpression of the <I>Vitreoscilla</I> hemoglobin gene is thought to significantly increase the oxygen utilization efficiency of the cells.</P><P><B>Results</B></P><P>An optimized <I>Vitreoscilla</I> hemoglobin (VHb) gene was introduced into <I>Mortierella alpina</I> via <I>Agrobacterium tumefaciens</I>-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 <I>Mortierella alpina</I>.</P><P><B>Conclusions</B></P><P>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.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s12896-017-0388-8) contains supplementary material, which is available to authorized users.</P>