Secondary metabolite flux distribution in Erwinia herbicola expressing Vitreoscilla hemoglobin

In this study Erwinia herbicola and its recombinants, one carrying the Vitreoscilla hemoglobin gene (vgb+) and the other missing it (vgb-), were used in a comparative fashion with respect to production of selected secondary metabolites. In this regard, this study is the first for investigation of the effect of such an endogenous recombinant oxygen-uptake system on microbial production of secondary metabolites as indol-3-asetik asit, ß-caroten, lycopene, vitamin C, phenazine, meropenem whose production are tightly regulated by oxygen. Further, the energetic state of bacteria were evaluated through the level of ATP and NAD.Compared to other two strains, the level of indol-3-asetik asit in the low L-tryptophan rich medium late phase vgb+ cultures was considerably high. Similarly, the level of this hormone in high glucose minimal medium cultures of vgb+ was higher than the host and vgb- strains. The rich medium cultures of vgb+ recombinant strain had also considerably higher levels of ß-carotene and lycopene. The vgb+ strain was also determined to have a higher level of vitamin C both in rich and glucose supplemented minimal media cultures. The presence of vgb was also determined to positively regulate the production of two antibiotics, phenazine and meropenem, under different carbon supply. The highest phenazine and meropenem levels were achieved with fructose and sucrose, respectively. Also, the recombinants had considerably higher oxygen uptake rates than the host strain. The levels of both ATP and NAD in rich cultures of vgb+ recombinant were higher than the host and vgb- recombinant.