title: Diversity and cold-active hydrolytic enzymes of culturable bacteria associated with Arctic sea ice, Spitzbergen.
abstract: The diversity of culturable bacteria associated with sea ice from four permanently cold fjords of Spitzbergen, Arctic Ocean, was investigated. A total of 116 psychrophilic and psychrotolerant strains were isolated under aerobic conditions at 4 degrees C. The isolates were grouped using amplified rDNA restriction analysis fingerprinting and identified by partial sequencing of 16S rRNA gene. The bacterial isolates fell in five phylogenetic groups: subclasses alpha and gamma of Proteobacteria, the Bacillus-Clostridium group, the order Actinomycetales, and the Cytophaga-Flexibacter-Bacteroides (CFB) phylum. Over 70% of the isolates were affiliated with the Proteobacteria gamma subclass. Based on phylogenetic analysis (<98% sequence similarity), over 40% of Arctic isolates represent potentially novel species or genera. Most of the isolates were psychrotolerant and grew optimally between 20 and 25 degrees C. Only a few strains were psychrophilic, with an optimal growth at 10-15 degrees C. The majority of the bacterial strains were able to secrete a broad range of cold-active hydrolytic enzymes into the medium at a cultivation temperature of 4 degrees C. The isolates that are able to degrade proteins (skim milk, casein), lipids (olive oil), and polysaccharides (starch, pectin) account for, respectively, 56, 31, and 21% of sea-ice and seawater strains. The temperature dependences for enzyme production during growth and enzymatic activity were determined for two selected enzymes, alpha-amylase and beta-galactosidase. Interestingly, high levels of enzyme productions were measured at growth temperatures between 4 and 10 degrees C, and almost no production was detected at higher temperatures (20-30 degrees C). Catalytic activity was detected even below the freezing point of water (at -5 degrees C), demonstrating the unique properties of these enzymes.
authors.affiliation: Institute of Technical Microbiology, Technical University Hamburg-Harburg, Kasernenstr 12, 21073 Hamburg, Germany.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Groudieva
authors.forename: Margarita
authors.initials: M
authors.lastname: Kambourova
authors.forename: Hoda
authors.initials: H
authors.lastname: Yusef
authors.forename: Maryna
authors.initials: M
authors.lastname: Royter
authors.forename: Ralf
authors.initials: R
authors.lastname: Grote
authors.forename: Hauke
authors.initials: H
authors.lastname: Trinks
authors.forename: Garabed
authors.initials: G
authors.lastname: Antranikian
mesh_terms: D000192:Actinomycetales / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D020561:Alphaproteobacteria / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D001110:Arctic Regions; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D041963:Bacteroidetes / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D020563:Gammaproteobacteria / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D016937:Gram-Positive Endospore-Forming Rods / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D006868:Hydrolysis; D007053:Ice; D009664:Norway; D010802:Phylogeny; D012623:Seawater / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007053:Ice