Extremophiles 

About: Extremophiles is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Halophile & Sulfolobus solfataricus. It has an ISSN identifier of 1431-0651. Over the lifetime, 1791 publications have been published receiving 65328 citations.

Potential of halotolerant and halophilic microorganisms for biotechnology.

Abstract: Halotolerant or halophilic microorganisms, able to live in saline environments, offer a multitude of actual or potential applications in various fields of biotechnology. The technical applications of bacteriorhodopsin comprise holography, spatial light modulators, optical computing, and optical memories. Compatible solutes are useful as stabilizers of biomolecules and whole cells, salt antagonists, or stress-protective agents. Biopolymers, such as biosurfactants and exopolysaccharides, are of interest for microbially enhanced oil recovery. Other useful biosubstances are enzymes, such as new isomerases and hydrolases, that are active and stable at high salt contents. Halotolerant microorganisms play an essential role in food biotechnology for the production of fermented food and food supplements. The degradation or transformation of a range of organic pollutants and the production of alternative energy are other fields of applications of these groups of extremophiles.

Halophilic adaptation of enzymes.

Abstract: It is now clear that the understanding of halophilic adaptation at a molecular level requires a strategy of complementary experiments, combining molecular biology, biochemistry, and cellular approaches with physical chemistry and thermodynamics. In this review, after a discussion of the definition and composition of halophilic enzymes, the effects of salt on their activity, solubility, and stability are reviewed. We then describe how thermodynamic observations, such as parameters pertaining to solvent-protein interactions or enzyme-unfolding kinetics, depend strongly on solvent composition and reveal the important role played by water and ion binding to halophilic proteins. The three high-resolution crystal structures now available for halophilic proteins are analyzed in terms of haloadaptation, and finally cellular response to salt stress is discussed briefly.

Pyrolobus fumarii, gen. and sp. nov., represents a novel group of archaea, extending the upper temperature limit for life to 113 degrees C

Abstract: A novel, irregular, coccoid-shaped archaeum was isolated from a hydrothermally heated black smoker wall at the TAG site at the Mid Atlantic Ridge (depth 3650 meters). It grew at between 90 degrees C and 113 degrees C (optimum 106 degrees C) and pH 4.0-6.5 (optimum 5.5) and 1%-4% salt (optimum 1.7%). The organism was a facultatively aerobic obligate chemolithoautotroph gaining energy by H2-oxidation. Nitrate, S2O3(2-), and low concentrations of O2 (up to 0.3% v/v) served as electron acceptors, yielding NH4+, H2S, and H2O as end products, respectively. Growth was inhibited by acetate, pyruvate, glucose, starch, or sulfur. The new isolate was able to form colonies on plates (at 102 degrees C) and to grow at a pressure of 25000 kPa (250 bar). Exponentially growing cultures survived a one-hour autoclaving at 121 degrees C. The GC content was 53 mol%. The core lipids consisted of glycerol-dialkyl glycerol tetraethers and traces of 2,3-di-O-phytanyl-sn-glycerol. The cell wall was composed of a surface layer of tetrameric protein complexes arranged on a p4-lattice (center-to-center distance 18.5 nm). By its 16S rRNA sequence, the new isolate belonged to the Pyrodictiaceae. Based on its GC-content, DNA homology, S-layer composition, and metabolism, we describe here a new genus, which we name Pyrolobus (the "fire lobe"). The type species is Pyrolobus fumarii (type strain 1A; DSM 11204).

Microbial diversity of soda lakes.

Abstract: Soda lakes are highly alkaline extreme environments that form in closed drainage basins exposed to high evaporation rates. Because of the scarcity of Mg2+ and Ca2+ in the water chemistry, the lakes become enriched in CO3 2− and Cl−, with pHs in the range 8 to >12. Although there is a clear difference in prokaryotic communities between the hypersaline lakes where NaCl concentrations are >15% w/v and more dilute waters, i.e., NaCl concentrations about 5% w/v, photosynthetic primary production appears to be the basis of all nutrient recycling. In both the aerobic and anaerobic microbial communities the major trophic groups responsible for cycling of carbon and sulfur have in general been identified. Systematic studies have shown that the microbes are alkaliphilic and many represent separate lineages within accepted taxa, while others show no strong relationship to known prokaryotes. Although alkaliphiles are widespread it seems probable that these organisms, especially those unique to the hypersaline lakes, evolved separately within an alkaline environment. Although present-day soda lakes are geologically quite recent, they have probably existed since archaean times, permitting the evolution of independent communities of alkaliphiles since an early period in the Earth's history.

Bacteria tolerant to organic solvents

Abstract: The toxic effects that organic solvents have on whole cells is an important drawback in the application of these solvents in environmental biotechnology and in the production of fine chemicals by whole-cell biotransformations. Hydrophobic organic solvents, such as toluene, are toxic for living organisms because they accumulate in and disrupt cell membranes. The toxicity of a compound correlates with the logarithm of its partition coefficient with octanol and water (log P(ow)). Substances with a log P(ow) value between 1 and 5 are, in general, toxic for whole cells. However, in recent years different bacterial strains have been isolated and characterized that can adapt to the presence of organic solvents. These strains grow in the presence of a second phase of solvents previously believed to be lethal. Different mechanisms contributing to the solvent tolerance of these strains have been found. Alterations in the composition of the cytoplasmic and outer membrane have been described. These adaptations suppress the effects of the solvents on the membrane stability or limit the rate of diffusion into the membrane. Furthermore, changes in the rate of the biosynthesis of the phospholipids were reported to accelerate repair processes. In addition to these adaptation mechanisms compensating the toxic effect of the organic solvents, mechanisms do exist that actively decrease the amount of the toxic solvent in the cells. An efflux system actively decreasing the amount of solvents in the cell has been described recently. We review here the current knowledge about exceptional strains that can grow in the presence of toxic solvents and the mechanisms responsible for their survival.