Long-Term Acclimation and Membrane Lipid Remodelling Enable Anaerobic Oxidation of Methane at Low-pH by 'Ca. Methanoperedens vercellensis'.

A granular enrichment culture of “Ca. Methanoperedens vercellensis” stays metabolically active down to pH 5.65 with acclimation, while immediate acid stress causes activity loss.

• Why it matters: Freshwater anaerobic methanotrophs have mostly been studied near neutral pH, yet methane oxidizers are found in acidic peatlands, leaving uncertainty about low-pH adaptation and sustained methane filtering.
• What they did: The culture was tested under low pH with and without acclimation time, alongside archaeal lipid profiling and biomass granule structural analyses to track membrane remodeling.
• The result: Population-wide acclimation enabled anaerobic methane oxidation at lower pH, linked to increased zwitterionic intact polar lipids over anionic lipids, with stable methane oxidation rate and enrichment proportion.

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