Abstract:

The phylogenetic diversity of culturable psychrophilic bacteria associ ated with sea ice from the high latitude regions of Canadian Basin and Chukchi Sea, Arctic, was investigated.A total of 34 psychropilic strains were isolated u sing three methods of (ⅳ) dilution plating (at 4 ℃), (©) bath culturing(at -1 ℃) and dilution plating, and (Ⅲ) cold shock (-20 ℃ for 24 h), bath culturin g and dilution plating under aerobic conditions. Sea-ice samples were exposed to -20 ℃ for 24 h that might reduce the number of common microorganisms and encourage outgrowth of psychrophilic strains. This process might be able to be introduce d to isolation psychrophilic bacteria from other environmental samples in future study. 16S rDNA nearly full-length sequence analysis revealed that psychrophilic strains felled in two phylogenetic divisions, γ-proteobacteria (in the genera Colwellia、Marinobacter、Shewanella、Glaciecola、Marinomonas and Pseudoalteromonas) and Cytophaga-Flexibacter-Bacteroides (Flavobacterium and Psychroflexus). Fifteen of bacterial isolates quite likely represented novel species (16S rDNA sequence similarity below 98%). One of strains(BSi20002) from Canadian Basin showe d 100% sequence similarity to that of Marinobacter sp. ANT8277 isolated from the Antarctic Weddell sea ice, suggesting bacteria may have a bipolar distribution at the species level.

Key words: Psychrophilic, Novel bacteria, Sea ice, Actic