The present disclosure relates to methods for more efficiently recycling reduced electron carriers in a hydrogen-oxidizing microorganism with an operable Calvin-Benson cycle; synthetic carbon fixation pathways that recycle reduced electron carriers more efficiently than the Calvin-Benson cycle, such as methods for enzymatically converting carbon dioxide to formate and assimilating the resulting formate into central carbon metabolism; methods for producing biochemical products; and recombinant hosts utilizing one or more synthetic carbon fixation pathways.

The present invention provides a method for constructing a threonine-producing engineered bacterium. According to the present invention, a 2-methylcitrate synthase 1-inactivated strain (Corynebacterium) is applied to the production of threonine, and the production of threonine produced by the 2-methylcitrate synthase 1-inactivated strain is increased by about 42% compared with that produced by an unengineered strain. When the application of the 2-methylcitrate synthase 1-inactivated strain is further combined with enhanced expression of at least one of aspartate aminotransferase, aspartate kinase, homoserine dehydrogenase, threonine synthase, NAD kinase, fructose-1,6-bisphosphatase 2 and the like in the threonine synthesis pathway, the production of threonine is improved. The method provides a new way for large-scale production of threonine and has high application value.