Desulfurella acetivoransにおけるプロピオン酸代謝経路の実験的解明
Desulfurella acetivorans, a strictly anaerobic sulfur-reducing deltaproteobacterium, is capable of heterotrophic growth on acetate oxidation or autotrophic growth using molecular hydrogen. This study demonstrates that the organism can also utilize propionate as a carbon source. Although a putative operon encoding methylcitrate cycle enzymes is present in the genome, no corresponding enzymatic activity was detected in cell extracts from propionate-grown cultures. Isotope tracer experiments using uniformly labeled [U-13C]propionate, combined with comparative proteomic profiling of acetate- versus propionate-grown cells, revealed that propionyl-CoA is instead carboxylated to methylmalonyl-CoA, which is subsequently converted to succinyl-CoA. This intermediate enters the TCA cycle, where it is ultimately converted to oxaloacetate; condensation with acetyl-CoA then yields citrate for further oxidation. These findings underscore the limitations of genome-based metabolic predictions and the necessity of experimental validation for accurate pathway characterization.
Propionyl-CoA is carboxylated to methylmalonyl-CoA and then converted to succinyl-CoA, which enters the TCA cycle. Despite genomic evidence for a methylcitrate cycle operon, this pathway is not functionally active during propionate growth.
This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/40012784