Effect of Salt Stress on Structure and Function of the Methanogenic Archaeal Community in Rice Field Soil

초록

The effects of salt stress on methane production and structure of the methanogenic archaeal community in rice field soil were investigated using gas chromatography and culture-independent molecular techniques. Addition of salts above 100 mM NaCl to soil slurries resulted in the suppression of CH4 production, decrease of H2 accumulation, and a transient accumulation of acetate. At the initial stage of methanogenesis, archaeal community was dominated by Methanosarcinaceae, rice cluster I, and Methanosaetaceae. Methanomicrobiaceae was not detected and three novel groups, rice cluster IV, rice cluster V, and deep-sea hydrothermal vent euryarchaeotic group 6, were appeared after 45 days of anaerobic incubation. Under salt stress of 300 mM NaCl, relative abundance of Methanosarcinaceae was increased, whereas methanogenic community structure of 500 mM NaCl was similar to that of control. Salt stress affected therefore not the species composition but the relative abundance of methanogenic archaea in anoxic rice field soils.