Production of the terpenoid-based biofuel α-bisabolene by metabolically engineered Corynebacterium glutamicum.

The depletion of fossil resources and their detrimental impact on global climate change necessitate the development of sustainable, renewable alternatives. Advanced fuels derived from microbial fermentation represent a promising route towards reducing dependency on petroleum-derived energy sources. In this respect, terpenoids emerge as attractive candidates for biofuel applications. Among terpenoids, α-bisabolene, a plant-derived sesquiterpenoid, has attracted attention as a potential diesel substitute owing to its high energy density and favorable combustion properties. In this study, the biotechnologically well-established Gram-positive bacterium Corynebacterium glutamicum was metabolically engineered for the biosynthesis of α-bisabolene for the first time. C. glutamicum exhibited robust growth in the presence of up to 1 g/L exogenously added α-bisabolene, showing its suitability as a host for α-bisabolene production. Among the different solvents for in situ product recovery, isopropyl myristate was identified as the most suitable to capture α-bisabolene, yielding 87.1 ± 7.1 mg/L. To address the "food vs. fuel" debate, α-bisabolene biosynthesis was achieved on glycerol, arabinose, and xylose, offering further sustainability and cost-effectiveness. By overexpressing dxs and idi, the production was increased to 296.5 ± 15.9 mg/L. This study broadens the biofuel product spectrum of C. glutamicum and supports their production based on alternative carbon sources.