Dimethyl sulfoxide-respiring bacteria in Suribati Ike, a hypersaline lake, in Antarctica and the marine environment

Dimethyl sulfoxide (DMSO) occurs worldwide, especially in marine environments as well as in lakes and rainwater. DMSO respiration by bacteria is assumed to play an important role in the sulfur cycle in Antarctica and on earth. We first studied whether DMSO-respiring bacteria existed in Antarctica. Eight strains were isolated that grew by DMSO respiration under anaerobic conditions from water of the halocline in a meromictic lake, Suribati Ike, near Syowa Station in Antarctica. All of them were related to known species belonging to the genus Marinobacter based on 16S rRNA gene sequences. Using a clone library analysis of 16S rRNA gene sequences, 38 of total 48 clones from water of the halocline were identified as Marinobacter. Studies on the various anaerobic respiration capabilities by bacteria in the halocline water found only DMSO respiration. Studies on bacteria with anaerobic respiration abilities in seawater from the Pacific Ocean and Seto Inland Sea, showed that either DMSO-respiring or nitrate-respiring bacteria were present and that all of isolates capable of DMSO respiration were closely related to Vibrio species