Inter-strain and inter-species inhibition mediated by a bacteriocin-like inhibitory substance (BLIS) from a pathogenic Vibrio harveyi strain VIB 571 was demonstrated against four isolates of the same species, and one culture each of a Vibrio sp., Vibrio fischeri, Vibrio gazogenes and Vibrio parahaemolyticus. The crude BLIS, which was obtained by ammonium-sulphate precipitation of the cell-free supernatant of a 72 h broth culture of strain VIB 571, was inactivated by lipase, proteinase K, pepsin, trypsin, pronase E, SDS and incubation at ¢60 6C for 10 min. The activity was stable between pH 2-11 for at least 5 h. Anion-exchange chromatography, gel filtration, SDS-PAGE and two-dimensional gel electrophoresis revealed the presence of a single major peak, comprising a protein with a pI of 5?4 and a molecular mass of~32 kDa. The N-terminal amino acid sequence of the protein comprised Asp-Glu-Tyr-Ile-Ser-X-Asn-Lys-X-Ser-Ser-Ala-Asp-Ile (with X representing cysteine or modified amino acid residues). A similarity search based on the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) generated peptide masses and the N-terminal sequence did not yield any significant matches.

The diversity and abundance of culturable bacteria in Kongsfjorden water (15 stations) and sediments (12 stations) were studied. Viable numbers ranged between 105–106 CFU l−1 in water and 102–104 CFU g−1 in the sediments. A total of 291 and 43 bacterial isolates were retrieved from the water (KJF) and sediments (FS), respectively. Based on 16S rRNA gene sequence similarities, the KJF and FS isolates were grouped into 49 and 23 phylotypes, respectively. The KJF and FS phylotypes represented three phyla namely, Actinobacteria, Bacteroidetes, and Proteobacteria. At the genus level, Flavobacterium and Shewanella and at the species level, Pseudoaltermonas arctica and Colwellia psychrerythraea were dominant in the water and sediments, respectively. Most phylotypes were psychrotolerant with upper growth temperature limit of 25–37 °C and tolerated 0.3–2.5 M NaCl and pH values of 5.0–11.0. Majority of the phylotypes produced one or more of the extracellular hydrolytic enzymes amylase, lipase, caseinase, urease, gelatinase, and DNase at 4 and 18 °C, while none were chitinolytic. Few of the FS phylotypes exhibited extracellular activity only at 4 or 18 °C. Nine FS and 21 KJF isolates were pigmented. The predominant cellular fatty acids were unsaturated, branched, and modified fatty acids, which are unique to cold-adapted bacteria.

Microbial antagonism in an Arctic soil habitat was demonstrated by assessing the inhibitory interactions between bacterial isolates from the same location. Of 139 isolates obtained from five soil samples, 20 antagonists belonging to the genera, Arthrobacter, Pseudomonas and Flavobacterium were identified. Inter-genus, inter-species and inter-strain antagonism was observed between the interacting members. The extent of antagonism was temperature dependent. In some cases, antagonism was enhanced at 4 °C but suppressed at 18 °C while in some the reverse phenomenon was observed. To interpret antagonism from an ecological perspective, the interacting members were delineated according to their positional roles in a theoretical antagonistic network. When only one antimicrobial producer (P) was present, all the other members permitted grouping into either sensitive (S) or resistant (R). Composite interactive types such as PSR, PS, PR or SR could be designated only when at least two producers were present. Mapping of all possible antagonistic interaction networks based on the individual positional roles of the interactive types illustrates the existence of complex and interconnected networks among microbial communities.

A novel Gram-negative, rod-coccus shaped, non-motile, strain, RS-3 T , was isolated from a sediment sample collected from the marine transect of Kongsfjorden, Ny-Å lesund, Svalbard, Arctic. Colonies and broth cultures were yellowish in colour due to the presence of carotenoids. Strain RS-3 T was positive for oxidase, aesculinase, caseinase, gelatinase and urease activities and negative for amylase, catalase, lipase, lysine decarboxylase, ornithine decarboxylase, DNase and b-galactosidase activities. The predominant fatty acids were iso-C

In the course of a study aimed at isolating bacteria from Arctic soils by a method that selectively enriches for rare bioactive actinomycetes, a Gram-stain-negative, pigmented, non-motile rod, designated MN12-7 T , was isolated. The salmon-pink strain was, based on 16S rRNA gene sequence similarity, found to be affiliated with the family Sphingobacteriaceae. Strain MN12-7 T was catalase-, oxidase-and cellulase-positive and lacked gelatinase, urease, lipase and pectinase. The predominant cellular fatty acids were summed feature 3 (comprising C 16 : 1 v7c and/or C 16 : 1 v6c), iso-C 15 : 0 and C 15 : 1 v6c. The major respiratory quinone of strain MN12-7 T was MK-7, and the major polar lipid was phosphatidylethanolamine in addition to phosphatidylserine, seven unidentified lipids and six unidentified aminolipids. The DNA G+C content of strain MN12-7 T was 38 mol%. Strain MN12-7 T formed a separate lineage in a cluster containing 'Candidatus comitans', with which it shared 92.3 % 16S rRNA gene sequence similarity. Based on the phenotypic characteristics and phylogenetic inference, strain MN12-7 T is proposed as a representative of a novel species in a new genus, Arcticibacter svalbardensis gen. nov., sp. nov. The type strain of the type species is MN12-7 T (5KCTC 32015 T 5CIP 110422 T ).