The Promoter of Zymomonas Mobilis Respiratory NADH Dehydrogenase (ndh) is Induced by Oxygen

Expression of the genes of engineered green fluorescent protein and the Zymomonas mobilis native malic enzyme from plasmid vectors under the Z. mobilis respiratory NADH dehydrogenase promoter (Pndh) was strongly enhanced by aeration, both in the wild type Zm6 and its respiratory-deficient mutant derivative Zm6-ndh backgrounds. Pndh in aerobically growing cultures was activated by about an order of magnitude relative to non-aerated control. Its induction approached the maximum level already at moderate aeration (1-5 % oxygen saturation in the medium). The strength of Pndh under aerobic conditions was comparable to, or even surpassed that of the strong Z. mobilis native promoter of glyceraldehyde-3-phosphate dehydrogenase. Although the mechanism of its oxygen-dependent induction is not known, Pndh might serve as a versatile inducible promoter for Z. mobilis metabolic engineering.