Energetics of syntrophic cooperation in methanogenic degradation.

摘要: Fatty acids and alcohols are key intermediates in the methanogenic degradation of organic matter, e.g., anaerobic sewage sludge digestors or freshwater lake sediments. They produced by classical fermenting bacteria for disposal electrons derived simultaneous substrate oxidations. Methanogenic can degrade primarily only one-carbon compounds. Therefore, acetate, propionate, ethanol, their higher homologs have to be fermented further These fermentations called secondary syntrophic fermentations. endergonic processes under standard conditions depend on intimate coupling with methanogenesis. The energetic situation prokaryotes cooperating these is problematic: free energy available reactions total conversion methane attributes each partner amounts range minimum biochemically convertible energy, i.e., 20 25 kJ per mol reaction. This amount corresponds one-third an ATP unit equivalent required a monovalent ion cross charged cytoplasmic membrane. Recent studies revealed that syntrophically synthesize substrate-level phosphorylation reinvest part ATP-bound into reversed electron transport processes, release at redox level accessible balance budget. findings allow us understand economy basis concepts from bioenergetics other microorganisms.