Isolation and characterization of a motile hydrogenotrophic methanogen from rice paddy field soil in Japan

Abstract

A hydrogenotrophic motile methanogen was isolated from flooded Japanese paddy field soil. Anaerobic incubation of the paddy soil on H 2–CO 2 at 20°C led to the enrichment of symmetrically curved motile autofluorescent rods. The methanogenic strain TM20-1 isolated from the culture was halotolerant and utilized H 2–CO 2, 2-propanol-CO 2, or formate as a sole methanogenic substrate. Based on the 16S rRNA gene sequence similarity (94.8%) with Methanospirillum hungateii, and on the physiological and phenotypic characteristics, TM20-1 was suggested to be a newly identified species belonging to the genus Methanospirillum. This is the first report of isolation of the genus Methanospirillum strain from a rice paddy field.