Shewanella gelidimarina sp. nov. and Shewanella frigidimarina sp. nov., novel Antarctic species with the ability to produce eicosapentaenoic acid (20:5 omega 3) and grow anaerobically by dissimilatory Fe(III) reduction

• Published in: International Journal of Systematic Bacteriology
• Main Authors: Bowman, JP, McCammon, SA, Nichols, DS, Skerratt, J, Rea, SM, Nichols, PD, McMeekin, TA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Society for General Microbiology 1997
• Subjects: Biological Sciences; Microbiology; Bacteriology; Antarctic; The Antarctic; Vestfold; Vestfold Hills; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.1099/00207713-47-4-1040; http://www.ncbi.nlm.nih.gov/pubmed/9336903; http://ecite.utas.edu.au/10403

A polyphasic taxonomic study was performed to characterize dissimilatory iron-reducing strains mostly isolated from Antarctic sea ice. The strains were isolated from samples of congelated (land-fast) sea ice, grease ice, and ice algal biomass collected from the coastal areas of the Vestfold Hills in eastern Antarctica (68S 78E). The strains were facultatively anaerobic, motile, and rod shaped, were capable of anaerobic growth either by fermentation of carbohydrates or by anaerobic respiration, and utilized a variety of electron acceptors, including nitrate, ferric compounds, and trimethylamine N-oxide. A phylogenetic analysis performed with 16S rRNA sequences showed that the isolates formed two groups representing novel lineages in the genus Shewanella. The first novel group included seawater- requiring, psychrophilic, chitinolytic strains which had DNA G+C contents of 48 tool%. The members of the second strain group were psychrotrophic and did not require seawater but could tolerate up to 9% NaCI. The strains of this group were also unable to degrade polysaccharides but could utilize a number of monosaccharides and disaccharides and had G+C contents of 40 to 43 tool%. The whole-cell-derived fatty acid profiles of the sea ice isolates were found to be similar to the profiles obtained for other Shewanella species. The omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) (20:53) was detected in all of the sea ice isolates at levels ranging from 2 to 16% of the total fatty acids. EPA was also found at high levels in Shewanella hanedai (19 to 22%) and Shewanella benthica (16 to 18%) but was absent in Shewanella alga and Shewanellla putrefaeiens. On the basis of polyphasic taxonomic data, the Antarctic iron-reducing strains are placed in two new species, Shewanella fridimarina sp. nov. (type strain, ACAM 591) and Shewanella gelidimarina sp. nov. (type strain, ACAM 456).