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In times of global warming and upcoming fossil fuel shortages, the demand for the replacement of current fossil fuel-based chemical production via the development of alternative technologies and sustainable resources has increased. As a possible solution, an approach that produces chemicals from C1 gases derived from industrial waste gas or syngas has been suggested, but inefficient costs and syngas contaminant-sensitive processes of chemical catalysts have limited C1 gas utilization. Recently, acetogenic bacteria have received much attention as potential biocatalysts capable of C1 gas valorization into value-added chemicals. A comprehensive overview of C1 gas conversion using acetogenic bacteria as biocatalysts and a wide range of value-added products converted from C1 gases is provided in this review. Additionally, several strategies for enhancing product yield and alcohol selectivity during the gas fermentation processes, converting native products into valuable longer carbon compounds through coupling gas fermentation with additional processes, and overcoming energetic limitations underlying acetogenic bacteria via strain engineering are discussed.

Here, we demonstrate the fabrication of 3D porous carbon scaffolds with tunable pore sizes that are comparable to the sizes of bacterial cells for their effective confinement. We utilized the sphere template method to fabricate the 3D porous carbon scaffolds with excellent pore arrangements and enlarged interconnected areas among the pores. The proposed 3D porous carbon scaffolds trapped about 40 times higher densities of Escherichia coli DH5α than conventional 3D porous reticulated vitreous carbon (RVC) scaffolds. Moreover, the proposed porous scaffolds effectively restrain the detachment of the attached cells from the scaffolds because of their geometries, thereby maintaining about 75% of the initial cell densities under repeated washing, whereas almost all the cells were washed away from the conventional 3D porous RVC scaffolds. This effective confinement of bacterial cells will assist in significantly improving the performance of cell-based biological applications.