Methanogenic archaea and their mediated methanogenic pathways in cold wetland

Abstract:

Cold wetlands contribute great portion of the global methane. This is attributed to the inhabited diverse microbes including methanogenic archaea, where they convert the organic materials to methane. This review summarized the recent studies on the diversity of methanogenic archaea, and methane emission pathways in the cold wetlands and their correlation with environmental parameters. The so-far studies indicated that acetate is the main methanogenic precursor in the wetlands located in cold regions, hydrogenothophic methanogenesis occurs mainly in wetlands located in the warm regions and acidic peat, while methanol- and methyl amine-derived methanogensis restricts in ocean and saline water. Zoige wetland situates on Qinghai-Tibet Plateau locating in the low latitude region but at high altitude. Our previous study indicated the significant methanogenic contribution of methanol in this wetland. Accordingly, the methylotrophic and aceticlastic Methanosarcinales and hydrogenotrphic Methanomicrobiales constitute the predominant wetland archaeal community. However, methanogenic pathways and methanogen community structures vary with the wetland soil types and their pH as well as the vegetations, like methanol-derived methane accounting for 17% total methane flux in Eleocharis valleculosa growing soil, while acetate contribute the main methane in Carex muliensis planted soil in Zoige wetland. Though playing an important role in methane emission of cold wetlands, the so-far cultured cold-adaptive methanogenic strains are very few. The low-temperature-responsive genomics analyses show that a global gene reperpoire may involve in cold adaptation in methanogenic archaea.