Extremophiles (EXTREMOPHILES)

Publisher: Springer Verlag

Journal description

Extremophiles features original research articles reviews and method papers on the biology molecular biology structure function and applications of life at high or low temperature pressure acidity alkalinity salinity or oxygen concentration; or in the presence of organic solvents heavy metals normally toxic substances radiation or host defense mechanisms. Fields covered: molecular biology biodiversity genetics macromolecular structure development growth biotechnology / fermentation technology ultrastructure biotransformation metabolism enzymology biomembranes bioenergetics physiology cell biology symbiosis ecology bioremediation methodologies evolution isolation phylogeny taxonomy

Current impact factor: 2.31

Impact Factor Rankings

2016 Impact Factor Available summer 2017
2014 / 2015 Impact Factor 2.306
2013 Impact Factor 2.174
2012 Impact Factor 2.203
2011 Impact Factor 2.941
2010 Impact Factor 2.16
2009 Impact Factor 2
2008 Impact Factor 1.782
2007 Impact Factor 2.317
2006 Impact Factor 1.921
2005 Impact Factor 2.125
2004 Impact Factor 1.897
2003 Impact Factor 1.955
2002 Impact Factor 2.165
2001 Impact Factor 2.291
2000 Impact Factor 2.688
1999 Impact Factor 3.133
1998 Impact Factor 2.593
1997 Impact Factor

Impact factor over time

Impact factor
Year

Additional details

5-year impact 2.58
Cited half-life 6.90
Immediacy index 0.48
Eigenfactor 0.00
Article influence 0.71
Website Extremophiles website
Other titles Extremophiles (Online)
ISSN 1431-0651
OCLC 42900820
Material type Document, Periodical, Internet resource
Document type Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

Springer Verlag

  • Pre-print
    • Author can archive a pre-print version
  • Post-print
    • Author can archive a post-print version
  • Conditions
    • Author's pre-print on pre-print servers such as arXiv.org
    • Author's post-print on author's personal website immediately
    • Author's post-print on any open access repository after 12 months after publication
    • Publisher's version/PDF cannot be used
    • Published source must be acknowledged
    • Must link to publisher version
    • Set phrase to accompany link to published version (see policy)
    • Articles in some journals can be made Open Access on payment of additional charge
  • Classification
    green

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Glucose-6-phosphate dehydrogenases (G6PDs) are important enzymes widely used in bioassay and biocatalysis. In this study, we reported the cloning, expression, and enzymatic characterization of G6PDs from the thermophilic bacterium Thermoanaerobacter tengcongensis MB4 (TtG6PD). SDS-PAGE showed that purified recombinant enzyme had an apparent subunit molecular weight of 60 kDa. Kinetics assay indicated that TtG6PD preferred NADP(+) (k cat/K m = 2618 mM(-1) s(-1), k cat = 249 s(-1), K m = 0.10 ± 0.01 mM) as cofactor, although NAD(+) (k cat/K m = 138 mM(-1) s(-1), k cat = 604 s(-1), K m = 4.37 ± 0.56 mM) could also be accepted. The K m values of glucose-6-phosphate were 0.27 ± 0.07 mM and 5.08 ± 0.68 mM with NADP(+) and NAD(+) as cofactors, respectively. The enzyme displayed its optimum activity at pH 6.8-9.0 for NADP(+) and at pH 7.0-8.6 for NAD(+) while the optimal temperature was 80 °C for NADP(+) and 70 °C for NAD(+). This was the first observation that the NADP(+)-linked optimal temperature of a dual coenzyme-specific G6PD was higher than the NAD(+)-linked and growth (75 °C) optimal temperature, which suggested G6PD might contribute to the thermal resistance of a bacterium. The potential of TtG6PD to measure the activity of another thermophilic enzyme was demonstrated by the coupled assays for a thermophilic glucokinase.
    No preview · Article · Feb 2016 · Extremophiles
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    ABSTRACT: Microbial biofilms are mainly studied due to detrimental effects on human health but they are also well established in industrial biotechnology for the production of chemicals. Moreover, biofilm can be considered as a source of novel drugs since the conditions prevailing within biofilm can allow the production of specific metabolites. Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 when grown in biofilm condition produces an anti-biofilm molecule able to inhibit the biofilm of the opportunistic pathogen Staphylococcus epidermidis. In this paper we set up a P. haloplanktis TAC125 biofilm cultivation methodology in automatic bioreactor. The biofilm cultivation was designated to obtain two goals: (1) the scale up of cell-free supernatant production in an amount necessary for the anti-biofilm molecule/s purification; (2) the recovery of P. haloplanktis TAC125 cells grown in biofilm for physiological studies. We set up a fluidized-bed reactor fermentation in which floating polystyrene supports were homogeneously mixed, exposing an optimal air-liquid interface to let bacterium biofilm formation. The proposed methodology allowed a large-scale production of anti-biofilm molecule and paved the way to study differences between P. haloplanktis TAC125 cells grown in biofilm and in planktonic conditions. In particular, the modifications occurring in the lipopolysaccharide of cells grown in biofilm were investigated.
    No preview · Article · Feb 2016 · Extremophiles
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    ABSTRACT: The multipartite genome of Deinococcus radiodurans forms toroidal structure. It encodes topoisomerase IB and both the subunits of DNA gyrase (DrGyr) while lacks other bacterial topoisomerases. Recently, PprA a pleiotropic protein involved in radiation resistance in D. radiodurans has been suggested for having roles in cell division and genome maintenance. In vivo interaction of PprA with topoisomerases has also been shown. DrGyr constituted from recombinant gyrase A and gyrase B subunits showed decatenation, relaxation and supercoiling activities. Wild type PprA stimulated DNA relaxation activity while inhibited supercoiling activity of DrGyr. Lysine133 to glutamic acid (K133E) and tryptophane183 to arginine (W183R) replacements resulted loss of DNA binding activity in PprA and that showed very little effect on DrGyr activities in vitro. Interestingly, wild type PprA and its K133E derivative continued interacting with GyrA in vivo while W183R, which formed relatively short oligomers did not interact with GyrA. The size of nucleoid in PprA mutant (1.9564 ± 0.324 µm) was significantly bigger than the wild type (1.6437 ± 0.345 µm). Thus, we showed that DrGyr confers all three activities of bacterial type IIA family DNA topoisomerases, which are differentially regulated by PprA, highlighting the significant role of PprA in DrGyr activity regulation and genome maintenance in D. radiodurans.
    No preview · Article · Feb 2016 · Extremophiles
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    ABSTRACT: An aromatic amino acid, Tyr or Trp, located in the esterase active site wall, is highly conserved, with hyperthermophilic esterases showing preference for Tyr and lower temperature esterases showing preference for Trp. In this study, we investigated the role of Tyr182 in the active site wall of hyperthermophilic esterase EstE1. Mutation of Tyr to Phe or Ala had a moderate effect on EstE1 thermal stability. However, a small-to-large mutation such as Tyr to His or Trp had a devastating effect on thermal stability. All mutant EstE1 enzymes showed reduced catalytic rates and enhanced substrate affinities as compared with wild-type EstE1. Hydrogen bond formation involving Tyr182 was unimportant for maintaining EstE1 thermal stability, as the EstE1 structure is already adapted to high temperatures via increased intramolecular interactions. However, removal of hydrogen bond from Tyr182 significantly decreased EstE1 catalytic activity, suggesting its role in stabilization of the active site. These results suggest that Tyr is preferred over a similarly sized Phe residue or bulky His or Trp residue in the active site walls of hyperthermophilic esterases for stabilizing the active site and regulating catalytic activity at high temperatures.
    No preview · Article · Feb 2016 · Extremophiles
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    ABSTRACT: We have previously reported a non-processive endo-type chitinase, ChiA, from a newly isolated marine psychrophilic bacterium, Pseudoalteromonas sp. DL-6. In this study, a processive exo-type chitinase, ChiC, was cloned from the same bacterium and characterized in detail. ChiC could hydrolyze crystalline chitin into (GlcNAc)2 as the only observed product. It exhibited high catalytic activity even at low temperatures, e.g. close to 0 °C, or in the presence of 5 M NaCl, suggesting that ChiC was a cold-adapted and highly salt-tolerant chitinase. ChiC could also hydrolyze other substrates, including chitosan and Avicel, indicating its broad substrate specificity. Sequence features indicated that ChiC was a multi-domain protein having a deep substrate-binding groove that was regarded as characteristic of processive exo-chitinases. Enzymatic hydrolysis of chitin by ChiC could be remarkably boosted in the presence of ChiA, suggesting the synergy of ChiC and ChiA. This work provided a new evidence to prove that marine psychrophilic bacteria utilized a synergistic enzyme system to degrade recalcitrant chitin.
    No preview · Article · Jan 2016 · Extremophiles
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    ABSTRACT: Thermostable lipases offer major biotechnological advantages over mesophilic lipases. In this study, an intracellular thermostable and organic solvent-tolerant lipase-producing strain YB103 was isolated from soil samples and identified taxonomically as Xanthomonas oryzae pv. oryzae. The lipase from X. oryzae pv. oryzae YB103 (LipXO) was purified 101.1-fold to homogeneity with a specific activity of 373.9 U/mg. The purified lipase showed excellent thermostability, exhibiting 51.1 % of its residual activity after incubation for 3 days at 70 °C. The enzyme showed optimal activity at 70 °C, suggesting it is a thermostable lipase. LipXO retained 75.1–154.1 % of its original activity after incubation in 20 % (v/v) hydrophobic organic solvents at 70 °C for 24 h. Furthermore, LipXO displayed excellent stereoselectivity (e.e.p >99 %) toward (S)-1-phenethyl alcohol in n-hexane. These unique properties of LipXO make it promising as a biocatalyst for industrial processes.
    No preview · Article · Jan 2016 · Extremophiles
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    ABSTRACT: Although Halomonas phages belonging to the families Myoviridae and Siphoviridae have been reported, no virulent Halomonas siphoviruses are known. In this study, a virulent bacteriophage, QHHSV-1, of the family Siphoviridae that specifically infects H. ventosae QH52-2 was isolated from the Qiaohou salt mine. Restriction analysis indicated that QHHSV-1 is a dsDNA virus with a genome size of 33.5-39.5 kb. Transmission electron microscopy showed that QHHSV-1 is a typical representative of the Siphoviridae, with an icosahedral head (47 nm in diameter) and a non-contractile tail (75 nm in length). We also assessed the adsorption rate of QHHSV-1 for the host bacterium and found significant inhibition after the addition of 10 mM CaCl2. Based on a one-step growth curve, we determined a latent period of 30 min and a burst size of 73 PFU/infected cell. At the optimal pH of 8.0, 25.9 and 15.2 % of the phages survived after a 60-min incubation at 50 and 60 °C, respectively. Phage replication was possible at a wide range of salt concentrations, from 2.0 to 20 % (w/v), with an optimum concentration of 5 %. The survival of QHHSV-1 at different salt concentrations decreased with time and 25 % survival after 25 days at 30 % salt concentration.
    No preview · Article · Dec 2015 · Extremophiles
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    ABSTRACT: The bacterium Deinococcus radiodurans-like all other organisms-introduces nucleotide modifications into its ribosomal RNA. We have previously found that the bacterium contains a Carbon-5 methylation on cytidine 2499 of its 23S ribosomal RNA, which is so far the only modified version of cytidine 2499 reported. Using homology search, we identified the open reading frame DR_0049 as the primary candidate gene for the methyltransferase that modifies cytidine 2499. Mass spectrometric analysis demonstrated that recombinantly expressed DR0049 protein methylates E. coli cytidine 2499 both in vitro and in vivo. We also inactivated the DR_0049 gene in D. radiodurans through insertion of a chloramphenicol resistance cassette. This resulted in complete absence of the cytidine 2499 methylation, which all together demonstrates that DR_0049 encodes the methyltransferase producing m(5)C2499 in D. radiodurans 23S rRNA. Growth experiments disclosed that inactivation of DR_0049 is associated with a severe growth defect, but available ribosome structures show that cytidine 2499 is positioned very similar in D. radiodurans harbouring the modification and E. coli without the modification. Hence there is no obvious structure-based explanation for the requirement for the C2499 posttranscriptional modification in D. radiodurans.
    No preview · Article · Nov 2015 · Extremophiles
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    ABSTRACT: The biodiversity and biotechnological potential of microbes from central Argentinean halophilic environments have been poorly explored. Salitral Negro and Colorada Grande salterns are neutral hypersaline basins exploded for NaCl extraction. As part of an ecological analysis of these environments, two bacterial and seven archaeal representatives were isolated, identified and examined for their biotechnological potential. The presence of hydrolases (proteases, amylases, lipases, cellulases and nucleases) and bioactive molecules (surfactants and antimicrobial compounds) was screened. While all the isolates exhibited at least one of the tested activities or biocompounds, the species belonging to Haloarcula genus were the most active, also producing antimicrobial compounds against their counterparts. In general, the biosurfactants were more effective against olive oil and aromatic compounds than detergents (SDS or Triton X-100). Our results demonstrate the broad spectrum of activities with biotechnological potential exhibited by the microorganisms inhabiting the Argentinean salterns and reinforce the importance of screening pristine extreme environments to discover interesting/novel bioactive molecules.
    No preview · Article · Sep 2015 · Extremophiles
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    ABSTRACT: A total of 33 halophilic protease producers were isolated from different salt samples collected from Emisal salt company at Lake Qarun, Fayoum, Egypt. Of these strains, an extremely halophilic strain that grew optimally at 30 % (w/v) NaCl was characterized and identified as Halobacterium sp. strain HP25 based on 16S rRNA gene sequencing and phenotypic characterization. A halo-alkali-thermophilic protease was purified in three successive steps from the culture supernatant. The purified halophilic protease consisted of a single polypeptide chain with a molecular mass of 21 kDa and was enriched 167-fold to a specific activity of 6350 U mg(-1). The purified enzyme was active over a broad pH range from 6.0 to 11.0, with maximum activity at pH 8.0, exhibited a broad temperature range from 30 to 80 °C with optimum activity at 60 °C, and was active at salt concentrations ranging from 5 to 25 % (w/v), with optimum activity at 17 % NaCl (w/v). The K M and V max values of the purified halophilic protease with casein as a substrate were 523 µg mL(-1) and 2500 µg min(-1) mL(-1), respectively. In addition, this enzyme was stable in the tested organic solvents and laundry detergents such methanol, propanol, butanol, hexane, Persil and Ariel. The unusual properties of this enzyme allow it to be used for various applications, such as the ripening of salted fish. Furthermore, its stability and activity in the presence of organic solvents and detergents also allow the use of this enzyme for further novel applications and as an additive in detergent formulations.
    No preview · Article · May 2015 · Extremophiles