Acetogenesis in the energy-starved deep biosphere - a paradox?

摘要: Under anoxic conditions in sediments, acetogens are often thought to be outcompeted by microorganisms performing energetically more favorable metabolic pathways, such as sulfate reduction or methanogenesis. Recent evidence from deep subseafloor sediments suggesting acetogenesis the presence of and methanogenesis has called this notion into question, however. Here I argue that can successfully coexist with reducers methanogens for multiple reasons. These include (1) substantial energy yields most reactions across wide range encountered subseafloor, (2) substrate spectra enable niche differentiation use different substrates and/or pooling a broad substrates, (3) reduced energetic cost biosynthesis among due reductive acetyl CoA pathway both production coupled ability many organic precursors produce key intermediate CoA. This leads general conclusion that, beside Gibbs free yields, variables strategy need taken account understand microbial survival energy-depleted biosphere.