초록
<P><I>Trichoderma reesei</I> is well known as an industrial workhorse fungus in cellulase production. The low dissolved oxygen supply in the highly viscous medium of <I>T. reesei</I> remains a major bottleneck that hampers growth and cellulase production in submerged fermentation. <I>Vitreoscilla</I> hemoglobin (VHb) has been demonstrated to improve metabolism and protein production in different heterologous hosts under hypoxic conditions, but the use of VHb in <I>T. reesei</I> remains uninvestigated. This study examines the effect of VHb in improving <I>T. reesei</I> performance in submerged fermentation. The VHb gene (<I>vgb</I>)-expressing cassette was successfully transformed into the TU-6 strain, integrated into the genome of <I>T. reesei</I>, and functionally expressed with biological activity, which was confirmed by carbon monoxide difference analysis. Compared to the parent strain, the expression of VHb increased the glucose consumption rate of the transformant. Moreover, in cellulase-inducing medium total protein secretion of the VHb expressing strain was 2.2-fold of the parental strain and the filter paper cellulase activity was increased by 58% under oxygen-limiting conditions. In summary, our results demonstrate that VHb has beneficial effects on improving total protein secretion and cellulase activity of <I>T. reesei</I> in submerged fermentation.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s13568-017-0507-x) contains supplementary material, which is available to authorized users.</P>