Carbon monoxide metabolism in freshwater anaerobic methanotrophic archaea
->Nature | More on "Archaea CO methane oxidation metabolism" at BigEarthData.ai | #Freshwater
‘Ca. Methanoperedens BLZ2’ oxidizes CO at high rates with respiratory and acetogenic metabolism To assess substrate oxidation dynamics, batch activity assays were performed with granular biomass from an ‘Ca. M. BLZ2’ enrichment culture (Fig. 1). Under nitrate respiratory conditions, the culture oxidized CO (14.3% vol/vol in the headspace) at high rates that reached 475 µmol d-1 gDW-1. Compared to that, the methane oxidation rate (in the absence of CO) proceeded more slowly at 210 µmol d-1 gDW-1 (Fig. 1A). When adding volumetric equal amounts of CO and CH4 (7.1% vol/vol each) the CO oxidation rate (952 µmol d-1 gDW-1) far exceeded the CH4 oxidation rate (43 µmol d-1 gDW-1) (Fig. 1B). This strong inhibition of CH4 oxidation by CO mirrors previous observations of substrate preference in ‘Ca. M. nitroreducens’ with formate16. To suppress bacterial activity, the following incubations were supplemented with 50 µg mL-1 antibiotics (SVAK, streptomycin, vancomycin, ampicillin, kanamycin). During incubations with CO/NO3− (CO oxidation rate 979 µmol d-1 gDW-1), no accumulation of CH4, formate or acetate was detected (Fig. 1C). In incubations with CH4/NO3− (CH4 oxidation rate 85 µmol d-1 gDW-1), CO2 was the only oxidation product (Fig. 1C). In contrast, when ‘Ca. M. BLZ2’ enriched biomass was...
