A functional approach to uncover the low-temperature adaptation strategies of the archaeon Methanosarcina barkeri

Low-temperature anaerobic digestion (ltad) technology is underpinned by a diverse microbial community. the methanogenic archaea represent a key functional group in these consortia, undertaking Co₂ reduction as well as acetate and methylated c1 metabolism with subsequent biogas (40 to 60% Ch₄ and 30 to 50% Co₂) formation. however, the cold adaptation strategies, which allow methanogens to function efficiently in ltad, remain unclear. here, a pure-culture proteomic approach was employed to study the functional characteristics of methanosarcina barkeri (optimum growth temperature, 37°c), which has been detected in ltad bioreactors. two experimental approaches were undertaken. the first approach aimed to characterize a low-temperature shock response (ltsr) of m. barkeri dsmz 800^T grown at 37°c with a temperature drop to 15°c, while the second experimental approach aimed to examine the low-temperature adaptation strategies (ltas) of the same strain when it was grown at 15°c. the latter experiment employed cell viability and growth measurements (optical density at 600 nm [OD₆₀₀]), which directly compared m. barkeri cells grown at 15°c with those grown at 37°c. during the ltsr experiment, a total of 127 proteins were detected in 37°c and 15°c samples, with 20 proteins differentially expressed with respect to temperature, while in the ltas experiment 39% of proteins identified were differentially expressed between phases of growth. functional categories included methanogenesis, cellular information processing, and chaperones. by applying a polyphasic approach (proteomics and growth studies), insights into the low-temperature adaptation capacity of this mesophilically characterized methanogen were obtained which suggest that the metabolically diverse methanosarcinaceae could be functionally relevant for ltad systems.