In incubations originated from the sediments of a ferruginous, early Earth analogue lake, we were surprised to discover that the interspecies association between Youngiibacter and Methanothrix was strictly dependent on conductive particles. Here is a link to our paper.
The implication of this study is that mineral-syntrophy could be the relic of ancestral associations between protocells splitting metabolic tasks, prior to the evolution of a complex EET-apparatus required for today’s interspecies associations.
Methanogenesis on different substrates in incubations from lake La Cruz. Methane production in initial slurry incubations provided with different substrates was stimulated by conductive particles (GAC or magnetite) independent of the media used (a) modified DSMZ 120 or (b) DSMZ 334. (c) Acetate accumulated in incubations without conductive particles was significantly lower at the addition of conductive particles. (d) For example, a third transfer free of sediment showed that methanogenesis and acetate consumption were both strictly dependent of the presence of conductive particles (colored symbols), and ceased if conductive particles were not added consistently for subsequent transfers (white symbols).
