Sugar-inducible promoters for manipulation of core metabolic pathways in the thermophilic acetogen <i>Thermoanaerobacter kivui</i>

Acetogenic bacteria are industrially relevant for conversion of synthesis gas (syngas, a mixture of hydrogen, H₂; carbon monoxide, CO; and carbon dioxide, CO₂) to products. Thermophilic bacteria have long been of interest as industrial strains due to their resistance to contamination. <i>Thermoanaerobacter kivui</i> is among the most thermophilic acetogens (T_opt = 66°C), with very short doubling times on H₂+CO₂ (&lt; 2 h), and is therefore a prime candidate for synthesis gas conversion at high temperatures. Here, we expanded <i>T. kivui</i>'s genetic toolkit by establishing a reporter gene operating at its temperature optimum, which was used to characterize sugar-inducible promoters. The identified promoters were used to control and engineer the metabolism of <i>T. kivui</i>, and may now be applied to elucidate remaining mysteries about the energetics of acetogenic metabolism.