Engineering Corynebacterium glutamicum for Geraniol Production

Geraniol is a monoterpenoid alcohol with various applications in food, cosmetics, and healthcare. Corynebacterium glutamicum is a potential platform for terpenoids production because it harbors the methylerythritol phosphate pathway. To engineer C . glutamicum to produce geraniol, two different truncated geraniol synthases (GESs) were respectively expressed, and strain LX02 expressing the truncated GESs from Valeriana officinalis (tVoGES) produced 0.3 mg/L of geraniol. Then, three geranyl diphosphate synthases (GPPSs) were combinatorially co-expressed with tVoGES to improve geraniol production. The amounts of produced geraniol were all higher than that produced by strain LX02. Strain LX03 co-expressing ERG20 F96W–N127W (ERG20 WW ) and tVoGES produced the highest amount, 5.4 mg/L. Subsequently, the co-overexpression of 1-deoxy- d -xylulose-5-phosphate synthase ( dxs ) and isopentenyl diphosphate isomerase ( idi ) further increased the production to 12.2 mg/L in strain LX03. Lastly, the production of geraniol was increased to 15.2 mg/L via fermentation optimization. To our knowledge, this is the first report on the engineering of C. glutamicum to produce geraniol and thus can serve as a reference for other monoterpenoid production studies.