Physiological characterization and promoter engineering of Acetobacterium wieringae for acetone production via gas fermentation

Abstract

The pressing need to mitigate environmental concerns has driven research into sustainable energy and chemical production methods that reduce carbon emissions. Gas fermentation offers a promising avenue for low-carbon fuel and chemical synthesis. Acetobacterium wieringae, particularly strain A. wieringae JM, has emerged as an attractive host for gas-based biorefineries due to its unique abilities, including growth in diverse gas compositions and pH ranges, and efficient growth on carbon monoxide without co-substrates. This study focuses on enhancing the potential of A. wieringae for acetone production through genetic modification. A transformation protocol was developed, and the acetone production operon from Clostridium acetobutylicum was introduced. Novel promoters were explored to widen gene expression possibilities in A. wieringae. The stability of the plasmid backbone pMTL83151 carrying replicon pCB102 was assessed. Additionally, the tolerance of A. wieringae to gas synthesis derived from biogenic residue gasification was evaluated for potential industrial application. Gas composition significantly influenced acetone production by A. wieringae, with distinct physiological effects observed between strain A. wieringae DSM 1911 and A. wieringae JM. Four constitutive promoters from A. wieringae JM and four from C. autoethanogenum were successfully expressed, exhibiting stronger activity than the reference Pthl promoter from C. acetobutylicum. Notably, A. wieringae JM demonstrated robust growth in synthesis gas from biomass gasification, though with physiological variations. This study unveils the intricate relationship between gas composition, physiological attributes, and acetone production in A. wieringae. The expanded promoter repertoire enhances genetic manipulation potential, propelling the strain's capacity for versatile gene expression. Moreover, the resilience of A. wieringae JM to gasification-derived gas synthesis highlights its viability for industrial implementation. These findings contribute to advancing the development of gas-based biorefineries, paving the way for sustainable chemical production with reduced environmental impact.