The genus Pseudoalteromonas is ubiquitous in the marine environment and can synthesize a wide range of extracellular compounds. Psychrotolerant Pseudoalteromonas sp. BSw20308 was isolated from the Chukchi Sea, a marginal sea of the Arctic Ocean. It produces a number of extracellular enzymes that can degrade polysaccharides and proteins. The BSw20308 genome was sequenced to 38.1-fold coverage, and the sequences were assembled into 146 contigs （〉~500 bp）. In total, 4 172 open reading frames （ORFs） with an average gene length of 987 bp were detected. At least 86 ORFs were predicted by sequence analysis to encode a variety of catalytic modules involved in the degradation of polysaccharides, proteins, and lipids. In addition, 36 ORFs were predicted to encode catalytic modules involved in the degradation of organic pollutants and halogenated compounds, and in the production of bioactive compounds. The draft genome sequence of BSw20308 provides new information about the ecological function and adaptation of the genus Pseudoalteromonas in Arctic marine environments, and also indicates its potential applica- tions in the biotechnology industries （e.g., enzymology, and pollutant degradation）.
Fluorescence in-situ hybridization （FISH） and 16S rRNA gene clone library analyses were used to determine the abundance and diversity of archaea in Prydz Bay, Antarctica. Correlation analysis was also performed to assess links between physicochemical parameters and archaeal abundance and diversity within the sea-ice. Samples of sea-ice and seawater were collected during the 26th Chinese National Antarctic Research Expedition. The results of FISH showed that archaea were relatively abundant within the top layer of the sea-ice, and correlation analysis suggested that the concentration of 4NH＋ might be one of the main factors underlying this distribution pattern. However, using 16S rRNA gene libraries, archaea were not detected in the top and middle layers of the sea-ice. All archaeal clones obtained from the bottom layer of the sea-ice were grouped into the Marine Group I Crenarchaeota while the archaeal clones from seawater were assigned to Marine Group I Crenarchaeota, Marine Group II Euryarchaeota, and Marine Group III Euryarchaeota. Overall, the ifndings of this study showed that the diversity of archaea in the sea-ice in Prydz Bay was low.
MA JifeiDU ZongjunLUO WeiYU YongZENG YixinCHEN BoLI Huirong
The evolutionary relationships and taxonomic position of two marine planktonic bacterial strains BSw20211 and BSwl0014, isolated from the Canada Basin and from the Southern Ocean, respectively, were determined using a polyphasic taxonomic approach. There was a close phylogenetic relationship between the two strains and most phenotypic properties were shared. Nonetheless, they were found to belong to different species of the genus Pseudoalteromonas on the basis of genotypic analyses. Findings were consistent with the suggestion that gyrB gene sequence comparison and DNA-DNA relatedness might better define phylogenetic relationships of bacteria at the species level. However, a cut-off value of 90% gyrB gene sequence similarity was not reliable for the differentiation of species within the genus Pseudoalteromonas.
