Markerless mutagenesis enables isoleucine biosynthesis solely from threonine in <i>Methanothermobacter marburgensis</i>

The autotrophic, hydrogenotrophic methanogen <i>Methanothermobacter marburgensis</i> is one of the best-studied model organisms in the field of thermophilic archaea. The fact that <i>M. marburgensis</i> shows robust growth and scalability in bioreactor systems makes it a highly suitable candidate for industrial-scale bioprocesses. Additionally, the reported study provides the tools for genetic engineering that enable sequential genome modification in <i>M. marburgensis</i>. Scalable bioreactor cultivation, the ability to genetically engineer, and the recent discovery of natural amino acid secretion in <i>M. marburgensis</i> set the cornerstone for the generation of the first cell factories in archaeal biotechnology to economically produce carbon dioxide-derived commodity and high-value chemicals at industrial scale.