Activity and diversity of haloalkaliphilic methanogens in Central Asian soda lakes

Methanogens are of biotechnological interest because of their importance in biogas production. Here we investigate the suitability of sediments from Central Asian soda lakes as inoculum for high pH methane-producing bioreactors. Methane production in these sediments was modest (up to 2.5 μmol mL sediment), with methanol and hydrogen as the preferred substrates. The responsible methanogenic community was characterized based on mcrA gene sequences. McrA gene sequences so far specific to these habitats indicated the presence of two clusters within the orders Methanobacteriales and Methanomicrobiales, one apparently including representatives of the genus Methanocalculus and another distantly related to the genus Methanobacterium.

► Soda lake sediments as promising inoculum for high pH methane producing bioreactors.
► Methane production in sediments with substrates methanol and hydrogen at pH 9.5–10.
► Novel mcrA gene sequences amplified from soda lake sediment DNA extracts.
► Results indicate presence of specialized haloalkaliphilic methanogenic populations.