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.

Several acidophilic, slightly thermophilic or thermophilic Gram-positive isolates were recovered from solfataric soil at Furnas on the Island of Sa 4 o Miguel in the Azores. Phylogenetic analysis of the 16S rRNA gene sequence showed that these organisms represented two novel species of the genus Alicyclobacillus. Strains FR-11 T and FR-1b had an optimum growth temperature of about 50 SC, whereas strains FR-3 and FR-6 T had an optimum growth temperature of about 60 SC. Biochemical, physiological and chemotaxonomic characteristics did not distinguish isolates FR-3 and FR-6T from the type strain of Alicyclobacillus acidocaldarius ; however, strains FR-11 T and FR-1b could be easily distinguished from the type strain of Alicyclobacillus acidoterrestris by the carbon source assimilation pattern and the fatty acid composition. On the basis of the phylogenetic analysis, physiological and biochemical characteristics, and fatty acid composition the name Alicyclobacillus hesperidum is proposed for the species represented by strains FR-11 T and FR-1b ; a formal name for the new genomic species represented by strains FR-3 and FR-6 T is not proposed at this time.

Using starch as a carbon source at a cultivation temperature of 4˚C, a number of Gram-negative, aerobic strains was isolated from sea-ice and sea-water samples collected at Spitzbergen in the Arctic. Analysis of the genetic diversity of the novel isolates by random amplification of polymorphic DNA (RAPD) and ERIC fingerprinting revealed a homogenic group of biofilm-forming bacteria that contained small extrachromosomal elements. As a representative of the group, strain Pull 5.3 T ,isolated from a sea-water sample, was used for detailed characterization. In recent years, increasing attention in research has been directed to cold-adapted micro-organisms that are able to grow at or close to the freezing point of water, namely psychrophiles. They are defined by an optimal temperature for growth of about 15˚C or below, a maximal growth temperature of about 20˚C and the ability to grow at 0˚C (Morita, 1975). In comparison, psychrotolerant microorganisms, sometimes also referred to as 'psychrotrophs', generally have optimum and maximum growth temperatures of 20˚C or above (Ingraham & Stokes, 1959).Cold-adapted micro-organisms are found in both permanently and temporarily cold habitats, which comprise more than 80 % of the Earth's biosphere. Oceans, covering threequarters of the Earth, polar regions (14 % of the Earth's surface), high mountains and deep lakes provide various aquatic and terrestrial cold environments where the temperature seldom or never reaches 5˚C (Gounot, 1999). The ability of micro-organisms to grow at low temperatures is not restricted to prokaryotes. A wide variety of micro-organisms, including bacteria, archaea, yeast, fungi and algae, is found in cold environments. These microorganisms are free-living in soil and fresh and saline waters or are associated with plants and cold-blooded animals such as fish or crustaceans. Among the bacteria, almost all types have been identified either after isolation (Ravenschlag et al., 1999; Bowman et al., 1997) or by detection in their natural habitats using a 16S rRNA approach (Fuhrman et al., 1993;DeLong et al., 1994;Vetriani et al., 1998). Unlike hyperthermophiles, they do not belong to new phyla. The majority of psychrophiles studied to date belong to the Gram-negative Proteobacteria. This is not surprising, since Gram-negatives are predominant in marine waters, where most investigations have been performed.Psychrophiles and psychrotolerant micro-organisms have a wide range of adaptations, including alterations in the protein and lipids of their membrane, energy-generation systems, protein synthesis and hydrolytic enzymes (Russell, 1998). Higher specific activity at low temperatures and thermosensitivity of cold-active enzymes provide a valuable source for exploration of novel biotechnological processes (Feller & Gerday, 1997). Since it has become clear that psychrophiles also represent a naturally occurring model for investigating protein adaptation to cold (Aghajari et al., 1998), an increasing number of novel bacterial strains from different Arctic and A...

Two hydrothermal springs (AI: 51 °C, pH 3; AIV: 92 °C, pH 8) were analysed to determine prokaryotic community composition. Using pyrosequencing, 93,576 partial 16S rRNA gene sequences amplified with V2/V3-specific primers for Bacteria and Archaea were investigated and compared to 16S rRNA gene sequences from direct metagenome sequencing without prior amplification. The results were evaluated by fluorescence in situ hybridization (FISH). While in site AIV Bacteria and Archaea were detected in similar relative abundances (Bacteria 40 %, Archaea 35 %), the acidic spring AI was dominated by Bacteria (68 %). In spring AIV the combination of 16S rRNA gene sequence analysis and FISH revealed high abundance (>50 %) of heterotrophic bacterial genera like Caldicellulosiruptor, Dictyoglomus, and Fervidobacterium. In addition, chemolithoautotrophic Aquificales were detected in the bacterial community with Sulfurihydrogenibium being the dominant genus. Regarding Archaea, only Crenarchaeota, were detected, dominated by the family Desulfurococcaceae (>50 %). In addition, Thermoproteaceae made up almost 25 %. In the acidic spring (AI) prokaryotic diversity was lower than in the hot, slightly alkaline spring AIV. The bacterial community of site AI was dominated by organisms related to the chemolithoautotrophic genus Acidithiobacillus (43 %), to the heterotrophic Acidicaldus (38 %) and to Anoxybacillus (7.8 %). This study reveals differences in the relative abundance of heterotrophic versus autotrophic microorganisms as compared to other hydrothermal habitats. Furthermore, it shows how different methods to analyse prokaryotic communities in complex ecosystems can complement each other to obtain an in-depth picture of the taxonomic composition and diversity within these hydrothermal springs.

Thermoanaerobacter yonseiensis sp. nov., a novel extremely thermophilic, xylose-utilizing bacterium that grows at up to 85 SC