Bacterial Plasmids in Antarctic Natural Microbial Assemblages

• Published in: Applied and Environmental Microbiology
• Main Authors: Kobori, Hiromi, Sullivan, Cornelius W., Shizuya, Hiroaki
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 1984
• Subjects: Antarctic; McMurdo Sound; Antarc*; Antarctica; Sea ice
• Online Access: http://dx.doi.org/10.1128/aem.48.3.515-518.1984; https://journals.asm.org/doi/pdf/10.1128/aem.48.3.515-518.1984

Samples of psychrophilic and psychrotrophic bacteria were collected from sea ice, seawater, sediments, and benthic or ice-associated animals in McMurdo Sound, Antarctica. A total of 155 strains were isolated and tested for the presence of plasmids by DNA agarose gel electrophoresis. Thirty-one percent of the isolates carried at least one kind of plasmid. Bacterial isolates taken from sediments showed the highest plasmid incidence (42%), and isolates from seawater showed the lowest plasmid incidence (20%). Plasmids were significantly more frequent in the strains which had been first isolated from low-nutrient media (46%) than in the strains which had been isolated from high-nutrient media (25%). Multiple forms of plasmids were observed in two-thirds of the plasmid-carrying strains. A majority of the plasmids detected were estimated to have a mass of 10 megadaltons or less. Among 48 plasmid-carrying strains, 7 showed antibiotic resistance. It is concluded that bacterial plasmids are ubiquitous in natural microbial assemblages of the pristine marine ecosystem of Antarctica.