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1.  Lysis of Halobacteria in Bacto-Peptone by Bile Acids 
All tested strains of halophilic archaebacteria of the genera Halobacterium, Haloarcula, Haloferax, and Natronobacterium lysed in 1% Bacto-Peptone (Difco) containing 25% NaCl, whereas no lysis was observed with other strains belonging to archaebacteria of the genera Halococcus, Natronococcus, and Sulfolobus, methanogenic bacteria, and moderately halophilic eubacteria. Substances in Bacto-Peptone which caused lysis of halobacteria were purified and identified as taurocholic acid and glycocholic acid. High-performance liquid chromatography analyses of peptones revealed that Bacto-Peptone contained nine different bile acids, with a total content of 9.53 mg/g, whereas much lower amounts were found in Peptone Bacteriological Technical (Difco) and Oxoid Peptone. Different kinds of peptones can be used to distinguish halophilic eubacteria and archaebacteria in mixed cultures from hypersaline environments.
PMCID: PMC202585  PMID: 16347619
2.  Low Water Activity Induces the Production of Bioactive Metabolites in Halophilic and Halotolerant Fungi 
Marine Drugs  2010;9(1):59-70.
The aim of the present study was to investigate indigenous fungal communities isolated from extreme environments (hypersaline waters of solar salterns and subglacial ice), for the production of metabolic compounds with selected biological activities: hemolysis, antibacterial, and acetylcholinesterase inhibition. In their natural habitats, the selected fungi are exposed to environmental extremes, and therefore the production of bioactive metabolites was tested under both standard growth conditions for mesophilic microorganisms, and at high NaCl and sugar concentrations and low growth temperatures. The results indicate that selected halotolerant and halophilic species synthesize specific bioactive metabolites under conditions that represent stress for non-adapted species. Furthermore, adaptation at the level of the chemical nature of the solute lowering the water activity of the medium was observed. Increased salt concentrations resulted in higher hemolytic activity, particularly within species dominating the salterns. The appearance of antibacterial potential under stress conditions was seen in the similar pattern of fungal species as for hemolysis. The active extracts exclusively affected the growth of the Gram-positive bacterium tested, Bacillus subtilis. None of the extracts tested showed inhibition of acetylcholinesterase activity.
doi:10.3390/md9010043
PMCID: PMC3039469  PMID: 21339946
hypersaline environments; black yeast; NaCl; secondary metabolites; hemolysis; antibacterial activity
3.  Extremely halophilic archaea and the issue of long-term microbial survival 
Halophilic archaebacteria (haloarchaea) thrive in environments with salt concentrations approaching saturation, such as natural brines, the Dead Sea, alkaline salt lakes and marine solar salterns; they have also been isolated from rock salt of great geological age (195–250 million years). An overview of their taxonomy, including novel isolates from rock salt, is presented here; in addition, some of their unique characteristics and physiological adaptations to environments of low water activity are reviewed. The issue of extreme long-term microbial survival is considered and its implications for the search for extraterrestrial life. The development of detection methods for subterranean haloarchaea, which might also be applicable to samples from future missions to space, is presented.
doi:10.1007/s11157-006-0007-y
PMCID: PMC3188376  PMID: 21984879
Extreme halophiles; Haloarchaea; Life detection; Microbial longevity; Salt mines; Salt sediments; Space missions; Subterranean; Taxonomy of halobacteriaceae
4.  Microbial life at high salt concentrations: phylogenetic and metabolic diversity 
Saline Systems  2008;4:2.
Halophiles are found in all three domains of life. Within the Bacteria we know halophiles within the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria, Spirochaetes, and Bacteroidetes. Within the Archaea the most salt-requiring microorganisms are found in the class Halobacteria. Halobacterium and most of its relatives require over 100–150 g/l salt for growth and structural stability. Also within the order Methanococci we encounter halophilic species. Halophiles and non-halophilic relatives are often found together in the phylogenetic tree, and many genera, families and orders have representatives with greatly different salt requirement and tolerance. A few phylogenetically coherent groups consist of halophiles only: the order Halobacteriales, family Halobacteriaceae (Euryarchaeota) and the anaerobic fermentative bacteria of the order Halanaerobiales (Firmicutes). The family Halomonadaceae (Gammaproteobacteria) almost exclusively contains halophiles. Halophilic microorganisms use two strategies to balance their cytoplasm osmotically with their medium. The first involves accumulation of molar concentrations of KCl. This strategy requires adaptation of the intracellular enzymatic machinery, as proteins should maintain their proper conformation and activity at near-saturating salt concentrations. The proteome of such organisms is highly acidic, and most proteins denature when suspended in low salt. Such microorganisms generally cannot survive in low salt media. The second strategy is to exclude salt from the cytoplasm and to synthesize and/or accumulate organic 'compatible' solutes that do not interfere with enzymatic activity. Few adaptations of the cells' proteome are needed, and organisms using the 'organic-solutes-in strategy' often adapt to a surprisingly broad salt concentration range. Most halophilic Bacteria, but also the halophilic methanogenic Archaea use such organic solutes. A variety of such solutes are known, including glycine betaine, ectoine and other amino acid derivatives, sugars and sugar alcohols. The 'high-salt-in strategy' is not limited to the Halobacteriaceae. The Halanaerobiales (Firmicutes) also accumulate salt rather than organic solutes. A third, phylogenetically unrelated organism accumulates KCl: the red extremely halophilic Salinibacter (Bacteroidetes), recently isolated from saltern crystallizer brines. Analysis of its genome showed many points of resemblance with the Halobacteriaceae, probably resulting from extensive horizontal gene transfer. The case of Salinibacter shows that more unusual types of halophiles may be waiting to be discovered.
doi:10.1186/1746-1448-4-2
PMCID: PMC2329653  PMID: 18412960
5.  Halococcus qingdaonensis sp. nov., a halophilic archaeon isolated from a crude sea-salt sample 
A Gram-negative, extremely halophilic, coccoid archaeal strain, CM5T, was isolated from a crude sea-salt sample collected near Qingdao, China. The organism grew optimally at 35–40 °C and pH 6.0 in the presence of 20 % (w/v) NaCl. Its colonies were red in colour and it could use glucose as a sole carbon source for growth. The 16S rRNA gene sequence of CM5T was most closely related to those of Halococcus species. Its pattern of antibiotic susceptibility was similar to those of other described Halococcus species. Biochemical tests revealed no sign of H2S production or gelatin liquefaction. The main polar lipids of strain CM5T were phosphatidylglycerol, phosphatidylglycerol methylphosphate and sulfated diglycosyl diether. No phosphatidylglycerol sulfate was present. The DNA G+C content of strain CM5T was 61.2 mol% and it gave DNA–DNA reassociation values of 33.7, 57.1 and 29.6 %, respectively, with Halococcus salifodinae DSM 8989T, Halococcus dombrowskii DSM 14522T and Halococcus morrhuae ATCC 17082T. Based on its morphological and chemotaxonomic properties and phylogenetic analysis of 16S rRNA gene sequence data, we propose that CM5T should be classified within a novel species, Halococcus qingdaonensis sp. nov., with strain CM5T (=CGMCC 1.4243T=JCM 13587T) as the type strain.
doi:10.1099/ijs.0.64673-0
PMCID: PMC3182530  PMID: 17329792
6.  Purification and characterization of an extreme halothermophilic protease from a halophilic bacterium Chromohalobacter sp. TVSP101 
An extreme halophilic bacterium was isolated from solar saltern samples and identified based on biochemical tests and 16S r RNA sequencing as Chromohalobacter sp. strain TVSP101. The halophilic protease was purified using ultrafiltration, ethanol precipitation, hydrophobic interaction column chromatography and gel permeation chromatography to 180 fold with 22% yield. The molecular mass of the protease determined by SDS PAGE was 66 kDa. The purified enzyme was salt dependent for its activity and stability with an optimum of 4.5 M NaCl. The optimum temperature for maximum protease activity was 75ºC. The protease was optimally active at pH 8 and retained more than 80% of its activity in the range of pH 7-10. Sucrose and glycine at 10% (w/v) were the most effective osmolytes, retained 100% activity in the absence of NaCl. The activity was completely inhibited by ZnCl2 (2 mM), 0.1% SDS and PMSF (1mM). The enzyme was not inhibited by 1mM of pepstatin, EDTA and PCMB. The protease was active and retained 100% it activity in 10% (v/v) DMSO, DMF, ethanol and acetone.
doi:10.1590/S1517-83822009000100002
PMCID: PMC3768512  PMID: 24031311
Chromohalobacter sp. TVSP101; halothermophilic protease; purification; organic solvents; osmolytes
7.  Isolation and Characterization of Haloanaerobacter chitinovorans gen. nov., sp. nov., a Halophilic, Anaerobic, Chitinolytic Bacterium from a Solar Saltern 
Two halophilic anaerobic bacteria, one of which had chitinolytic activity, were isolated from a solar saltern in southern California. These organisms were long, gram-negative, motile, flexible rods. The biochemical and physiological characteristics of these bacteria were very similar but were different from the characteristics of other haloanaerobic bacteria. Both grew at salt concentrations ranging from 0.5 to 5 M and at temperatures ranging from 23 to 50°C. They were sensitive to chloramphenicol but resistant to penicillin, carbenicillin, d-cycloserine, streptomycin, and tetracycline. An analysis of DNAs and whole-cell proteins showed that they were closely related taxonomically and distinguishable from other halophilic anaerobic bacteria. They exhibited 92.3 to 100% DNA homology as determined by DNA-DNA hybridization. The guanine-plus-cytosine contents of their DNAs were 34.8±1 mol%. The two isolates, strains W5C8 and W3C1, differed from other halophilic anaerobic bacteria sufficiently to support establishment of a new genus and species, Haloanaerobacter chitinovorans. Strain W5C8 exhibited chitinolytic activity and is designated the type strain. Two chitin-induced extracellular proteins with molecular weights of 38 × 103 and 40 × 103 were detected in strain W5C8.
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PMCID: PMC195201  PMID: 16348626
8.  Characterization of Halorubrum sfaxense sp. nov., a New Halophilic Archaeon Isolated from the Solar Saltern of Sfax in Tunisia 
An extremely halophilic archaeon, strain ETD6, was isolated from a marine solar saltern in Sfax, Tunisia. Analysis of the 16S rRNA gene sequence showed that the isolate was phylogenetically related to species of the genus Halorubrum among the family Halobacteriaceae, with a close relationship to Hrr. xinjiangense (99.77% of identity). However, value for DNA-DNA hybridization between strain ETD6 and Hrr.xinjiangense were about 24.5%. The G+C content of the genomic DNA was 65.1 mol% (T(m)). Strain ETD6 grew in 15–35% (w/v) NaCl. The temperature and pH ranges for growth were 20–55°C and 6–9, respectively. Optimal growth occurred at 25% NaCl, 37°C, and pH 7.4. The results of the DNA hybridization against Hrr. xinjiangense and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain ETD6 from other Hrr. species. Therefore, strain ETD6 represents a novel species of the genus Halorubrum, for which the name Hrr. sfaxense sp. nov. is proposed. The Genbank EMBL-EBI accession number is GU724599.
doi:10.1155/2011/240191
PMCID: PMC3132631  PMID: 21754938
9.  Microbiology Study of a Hypersaline Lake in French Somaliland 
Applied Microbiology  1974;27(5):819-822.
In a study of a lake having a higher concentration of salts than the Dead Sea, all of the heterotrophic bacteria isolated were aerobes; no strictly anaerobic strains were found. Ninety percent of the strains were euryhalines and ten percent were strict halophiles. The extreme halophiles belonged to the species Halobacterium trapanicum and Halococcus morrhuae.
PMCID: PMC380149  PMID: 4833284
10.  Halocin SH10 production by an extreme haloarchaeon Natrinema sp. BTSH10 isolated from salt pans of South India 
Halobacteria, members of the domain Archaea that live under extremely halophilic conditions, are often considered as dependable source for deriving novel enzymes, novel genes, bioactive compounds and other industrially important molecules. Protein antibiotics have potential for application as preserving agents in food industry, leather industry and in control of infectious bacteria. Halocins are proteinaceous antibiotics synthesized and released into the environment by extreme halophiles, a universal characteristic of halophilic bacteria. Herein, we report the production of halocin (SH10) by an extremely halophilic archeon Natrinema sp. BTSH10 isolated from salt pan of Kanyakumari, Tamilnadu, India and optimization of medium for enhanced production of halocin. It was found that the optimal conditions for maximal halocin production were 42 °C, pH 8.0, and 104 h of incubation at 200 rpm with 2% (V/V) inoculum concentration in Zobell’s medium containing 3 M NaCl, Galactose, beef extract, and calcium chloride as additional supplements. Results indicated scope for fermentation production of halocin for probable applications using halophilic archeon Natrinema sp. BTSH10.
doi:10.1016/j.sjbs.2013.02.002
PMCID: PMC3730894  PMID: 23961237
Haloarcheon; Natrinema sp.; Halocin; Production; Medium optimization
11.  Solar salt lake as natural environmental source for extraction halophilic pigments 
Iranian Journal of Microbiology  2010;2(2):103-109.
Background and Objectives
Halophilic bacteria produce a variety of pigments, which function as immune modulators and have prophylactic action against cancers. In this study, colorful halophilic bacteria were isolated from solar salt lake and their pigments was extracted in optimal environmental conditions and compared with the pigments of Halorubrum sodomense ATCC 33755.
Materials and Methods
Water samples from the solar salt lake in Imam Khomeini port in southwest of Iran were used as a source for isolation of pigment-producing bacteria. Halorubrum sodomense ATCC 33755 was used as control for pigment production. The conditions for optimum growth and pigment production were established for the isolated bacteria. Pigment were analyzed by spectrophotometer, TLC and NMR assay. The 16S rRNA genes were sequenced and results were used to differentiate haloarchaea from halophilic bacterial strains.
Results
Among the isolated strains, YS and OS strains and Halorubrum sodomense were recognized as moderate and extremely halophile with maximum growth in the presence of 15% and 30% NaCl concentrations, respectively. Experiments conducted to find out the optimum conditions for growth and pigment production temperature at 25°C, pH = 7.2 and shaking conditions at 120 rpm for three strains. Without shaking, little growth with no pigment production was observed. Total pigment produced by red, yellow and orange strains was measured at 240, 880 and 560 mg per dry cell weight respectively. Amplification yielded bands of to isolated strains only observed with bacteria primers. This result suggesting the YS and OS strains were not haloarchaea.
Conclusion
The isolated halophilic bacteria produced much higher amounts of pigments than Halorubrum sodomense. Photo intermediates including metarhodopsin II (meta II, λmax=380 nm) were determined as major pigment in Halorubrum sodomense.
PMCID: PMC3279771  PMID: 22347558
Halorubrum sodomense; haloarchaea; salt lake; metarhodopsin II; pigment
12.  Base Sequence Homology and Renaturation Studies of the Deoxyribonucleic Acid of Extremely Halophilic Bacteria 
Journal of Bacteriology  1969;99(1):255-262.
The genetic relatedness among various strains of halophilic bacteria has been assessed by deoxyribonucleic acid-deoxyribonucleic acid (DNA-DNA) duplex formation and ribosomal ribonucleic acid (RNA) hybridization. All of the strains of extremely halophilic rods are closely related, and the extent of divergence of base sequence is similar for the major and minor DNA components. Parallel experiments with ribosomal RNA revealed a relationship between the extremely halophilic rods and cocci and a more distant relationship to moderate halophiles and to a photosynthetic extreme halophile. Renaturation studies of halophile DNA exclude the possibility that the satellite DNA represents multiple copies of a small episomal element. The kinetics of DNA renaturation show that the genome size of the extreme and moderate halophiles is similar to that of Escherichia coli.
PMCID: PMC249996  PMID: 5802609
13.  Screening and isolation of halophilic bacteria producing industrially important enzymes 
Brazilian Journal of Microbiology  2012;43(4):1595-1603.
Halophiles are excellent sources of enzymes that are not only salt stable but also can withstand and carry out reactions efficiently under extreme conditions. The aim of the study was to isolate and study the diversity among halophilic bacteria producing enzymes of industrial value. Screening of halophiles from various saline habitats of India led to isolation of 108 halophilic bacteria producing industrially important hydrolases (amylases, lipases and proteases). Characterization of 21 potential isolates by morphological, biochemical and 16S rRNA gene analysis found them related to Marinobacter, Virgibacillus, Halobacillus, Geomicrobium, Chromohalobacter, Oceanobacillus, Bacillus, Halomonas and Staphylococcus genera. They belonged to moderately halophilic group of bacteria exhibiting salt requirement in the range of 3–20%. There is significant diversity among halophiles from saline habitats of India. Preliminary characterization of crude hydrolases established them to be active and stable under more than one extreme condition of high salt, pH, temperature and presence of organic solvents. It is concluded that these halophilic isolates are not only diverse in phylogeny but also in their enzyme characteristics. Their enzymes may be potentially useful for catalysis under harsh operational conditions encountered in industrial processes. The solvent stability among halophilic enzymes seems a generic novel feature making them potentially useful in non-aqueous enzymology.
doi:10.1590/S1517-838220120004000044
PMCID: PMC3769037  PMID: 24031991
Halophiles; Biodiversity; Halophilic enzymes; Hydrolases; Solvent-stable.
14.  Molecular signature of hypersaline adaptation: insights from genome and proteome composition of halophilic prokaryotes 
Genome Biology  2008;9(4):R70.
A comparative genomic and proteomic study of halophilic and non-halophilic prokaryotes identifies specific genomic and proteomic features typical of halophilic species that are independent from genomic GC-content and taxonomic position.
Background
Halophilic prokaryotes are adapted to thrive in extreme conditions of salinity. Identification and analysis of distinct macromolecular characteristics of halophiles provide insight into the factors responsible for their adaptation to high-salt environments. The current report presents an extensive and systematic comparative analysis of genome and proteome composition of halophilic and non-halophilic microorganisms, with a view to identify such macromolecular signatures of haloadaptation.
Results
Comparative analysis of the genomes and proteomes of halophiles and non-halophiles reveals some common trends in halophiles that transcend the boundary of phylogenetic relationship and the genomic GC-content of the species. At the protein level, halophilic species are characterized by low hydrophobicity, over-representation of acidic residues, especially Asp, under-representation of Cys, lower propensities for helix formation and higher propensities for coil structure. At the DNA level, the dinucleotide abundance profiles of halophilic genomes bear some common characteristics, which are quite distinct from those of non-halophiles, and hence may be regarded as specific genomic signatures for salt-adaptation. The synonymous codon usage in halophiles also exhibits similar patterns regardless of their long-term evolutionary history.
Conclusion
The generality of molecular signatures for environmental adaptation of extreme salt-loving organisms, demonstrated in the present study, advocates the convergent evolution of halophilic species towards specific genome and amino acid composition, irrespective of their varying GC-bias and widely disparate taxonomic positions. The adapted features of halophiles seem to be related to physical principles governing DNA and protein stability, in response to the extreme environmental conditions under which they thrive.
doi:10.1186/gb-2008-9-4-r70
PMCID: PMC2643941  PMID: 18397532
15.  Biochemical and serological evidence for an RNase E-like activity in halophilic Archaea. 
Journal of Bacteriology  1997;179(4):1180-1185.
Endoribonuclease RNase E appears to control the rate-limiting step that mediates the degradation of many mRNA species in bacteria. In this work, an RNase E-like activity in Archaea is described. An endoribonucleolytic activity from the extreme halophile Haloarcula marismortui showed the same RNA substrate specificity as the Escherichia coli RNase E and cross-reacted with a monoclonal antibody raised against E. coli RNase E. The archaeal RNase E activity was partially purified from the extreme halophilic cells and shown, contrary to the E. coli enzyme, to require a high salt concentration for cleavage specificity and stability. These data indicate that a halophilic RNA processing enzyme can specifically recognize and cleave mRNA from E. coli in an extremely salty environment (3 M KCI). Having recently been shown in mammalian cells (A. Wennborg, B. Sohlberg, D. Angerer, G. Klein, and A. von Gabain, Proc. Natl. Acad. Sci. USA 92:7322-7326, 1995), RNase E-like activity has now been identified in all three evolutionary domains: Archaea, Bacteria, and Eukarya. This strongly suggests that mRNA decay mechanisms are highly conserved despite quite different environmental conditions.
PMCID: PMC178814  PMID: 9023200
16.  Biological properties of carotenoids extracted from Halobacterium halobium isolated from a Tunisian solar saltern 
Background
Bioactive molecules have received increasing attention due to their nutraceutical attributes and anticancer, antioxidant, antiproliferative and apoptosis-inducing properties. This study aimed to investigate the biological properties of carotenoids extracted from Archaea.
Methods
Halophilic Archaea strains were isolated from the brine of a local crystallizer pond (TS7) of a solar saltern at Sfax, Tunisia. The most carotenoid-producing strain (M8) was investigated on heptoma cell line (HepG2), and its viability was assessed by the MTT-test. The cells were incubated with different sub-lethal extract rates, with carotenoid concentrations ranging from 0.2 to 1.5 μM. Antioxidant activity was evaluated through exposing the cells to sub-lethal extract concentrations for 24 hours and then to oxidative stress induced by 60 μM arachidonic acid and 50 μM H2O2.
Results
Compared to non-treated cells, bacterial carotenoid extracts inhibited HepG2 cell viability (50%). A time and dose effect was observed, with cell viability undergoing a significant (P < 0.05) decrease with extract concentration. After exposure to oxidative stress, control cells underwent a significant (P < 0.05) decrease in viability as compared to the non-treated cells.
Conclusions
The bacterial extracts under investigation were noted to exhibit the strongest free radical scavenging activity with high carotenoid concentrations. The carotenoid extract also showed significant antiproliferative activity against HepG2 human cancer cell lines.
doi:10.1186/1472-6882-13-255
PMCID: PMC3853157  PMID: 24090008
Archaea; Halobacteria; Solar saltern; Carotenoids; HepG2 human cancer cells
17.  Distribution of compatible solutes in the halophilic methanogenic archaebacteria. 
Journal of Bacteriology  1991;173(17):5352-5358.
Accumulation of compatible solutes, by uptake or de novo synthesis, enables bacteria to reduce the difference between osmotic potentials of the cell cytoplasm and the extracellular environment. To examine this process in the halophilic and halotolerant methanogenic archaebacteria, 14 strains were tested for the accumulation of compatible solutes in response to growth in various extracellular concentrations of NaCl. In external NaCl concentrations of 0.7 to 3.4 M, the halophilic methanogens accumulated K+ ion and low-molecular-weight organic compounds. beta-Glutamate was detected in two halotolerant strains that grew below 1.5 M NaCl. Two unusual beta-amino acids, N epsilon-acetyl-beta-lysine and beta-glutamine (3-aminoglutaramic acid), as well as L-alpha-glutamate were compatible solutes among all of these strains. De novo synthesis of glycine betaine was also detected in several strains of moderately and extremely halophilic methanogens. The zwitterionic compounds (beta-glutamine, N epsilon-acetyl-beta-lysine, and glycine betaine) and potassium were the predominant compatible solutes among the moderately and extremely halophilic methanogens. This is the first report of beta-glutamine as a compatible solute and de novo biosynthesis of glycine betaine in the methanogenic archaebacteria.
PMCID: PMC208245  PMID: 1909318
18.  Isolation and Characterization of a Moderately Halophilic Methanogen from a Solar Saltern 
A moderately halophilic methanogenic bacterium was enriched with trimethylamine and isolated from the sediment of a solar salt pond (total dissolved solids of pond water, 250 g/liter; pH 7.5). The isolate (strain SF1, DSM 3243) was an irregular coccus which stained gram negative, with a diameter of 1 μm and a thin monolayered cell wall. The organism grew singly, in pairs, and in irregular clumps. Colonies were tannish yellow, circular, with entire edges, and about 1 mm in diameter within 1 week. Only methylamines or methanol was used for growth and methanogenesis. Most rapid growth (doubling time, 10.2 h) occurred at a temperature of 37°C and a pH of 7.4. The optimum NaCl concentration was 2.1 M. Yeast extract or rumen fluid was required. The isolate was lysed by sodium dodecyl sulfate (0.1 g/liter) and was sensitive to chloramphenicol. The G+C content of the DNA was 41 (±1) mol%.
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PMCID: PMC238586  PMID: 16346832
19.  Magnesium and Manganese Content of Halophilic Bacteria 
Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation.
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PMCID: PMC203574  PMID: 16347151
20.  Isolation and Characterization of a Phosphate-Solubilizing Halophilic Bacterium Kushneria sp. YCWA18 from Daqiao Saltern on the Coast of Yellow Sea of China 
Phosphate-solubilizing bacteria (PSB) function in soil phosphorus cycle, increasing the bioavailability of soil phosphorus for plants. Isolation and application of salt-tolerant or halophilic PSB will facilitate the development of saline-alkali soil-based agriculture. A moderately halophilic bacterium was isolated from the sediment of Daqiao saltern on the eastern coast of China, which also performs phosphate-solubilizing ability. The bacterium was assigned to genus Kushneria according to its 16S rRNA gene sequence, and accordingly named as Kushneria sp. YCWA18. The fastest growth was observed when the culturing temperature was 28°C and the concentration of NaCl was 6% (w/v). It was founds that the bacterium can survive at a concentration of NaCl up to 20%. At the optimum condition, the bacterium solubilized 283.16 μg/mL phosphorus in 11 days after being inoculated in 200 mL Ca3(PO4)2 containing liquid medium, and 47.52 μg/mL phosphorus in 8 days after being inoculated in 200 mL lecithin-containing liquid medium. The growth of the bacterium was concomitant with a significant decrease of acidity of the medium.
doi:10.1155/2011/615032
PMCID: PMC3118493  PMID: 21716683
21.  Endospores of halophilic bacteria of the family Bacillaceae isolated from non-saline Japanese soil may be transported by Kosa event (Asian dust storm) 
Saline Systems  2005;1:8.
Background
Generally, extremophiles have been deemed to survive in the extreme environments to which they had adapted to grow. Recently many extremophiles have been isolated from places where they are not expected to grow. Alkaliphilic microorganisms have been isolated from acidic soil samples with pH 4.0, and thermophiles have been isolated from samples of low temperature. Numerous moderately halophilic microorganisms, defined as those that grow optimally in media containing 0.5–2.5 Molar (3–15%) NaCl, and halotolerant microorganisms that are able to grow in media without added NaCl and in the presence of high NaCl have been isolated from saline environments such as salterns, salt lakes and sea sands. It has tacitly been believed that habitats of halophiles able to grow in media containing more than 20% (3.4 M) are restricted to saline environments, and no reports have been published on the isolation of halophiles from ordinary garden soil samples.
Results
We demonstrated that many halophilic bacteria that are able to grow in the presence of 20% NaCl are inhabiting in non-saline environments such as ordinary garden soils, yards, fields and roadways in an area surrounding Tokyo, Japan. Analyses of partial 16S rRNA gene sequences of 176 isolates suggested that they were halophiles belonging to genera of the family Bacillaceae, Bacillus (11 isolates), Filobacillus (19 isolates), Gracilibacillus (6 isolates), Halobacillus (102 isolates), Lentibacillus (1 isolate), Paraliobacillus (5 isolates) and Virgibacillus (17 isolates). Sequences of 15 isolates showed similarities less than 92%, suggesting that they may represent novel taxa within the family Bacillaceae.
Conclusion
The numbers of total bacteria of inland soil samples were in a range from 1.4 × 107/g to 1.1 × 106/g. One tenth of the total bacteria was occupied by endospore-forming bacteria. Only very few of the endospore-forming bacteria, roughly 1 out of 20,000, are halophilic bacteria. Most of the halophilic bacteria were surviving as endospores in the soil samples, in a range of less than 1 to about 500/g soil. Samples collected from seashore in a city confronting Tokyo Bay gave the total numbers of bacteria and endospores roughly 1000 time smaller than those of inland soil samples. Numbers of halophilic bacteria per gram, however, were almost the same as those of inland soil samples. A possible source of the halophilic endospore originating from Asian dust storms is discussed.
doi:10.1186/1746-1448-1-8
PMCID: PMC1283985  PMID: 16242015
22.  Synchronous Effects of Temperature, Hydrostatic Pressure, and Salinity on Growth, Phospholipid Profiles, and Protein Patterns of Four Halomonas Species Isolated from Deep-Sea Hydrothermal- Vent and Sea Surface Environments 
Applied and Environmental Microbiology  2004;70(10):6220-6229.
Four strains of euryhaline bacteria belonging to the genus Halomonas were tested for their response to a range of temperatures (2, 13, and 30°C), hydrostatic pressures (0.1, 7.5, 15, 25, 35, 45, and 55 MPa), and salinities (4, 11, and 17% total salts). The isolates were psychrotolerant, halophilic to moderately halophilic, and piezotolerant, growing fastest at 30°C, 0.1 MPa, and 4% total salts. Little or no growth occurred at the highest hydrostatic pressures tested, an effect that was more pronounced with decreasing temperatures. Growth curves suggested that the Halomonas strains tested would grow well in cool to warm hydrothermal-vent and associated subseafloor habitats, but poorly or not at all under cold deep-sea conditions. The intermediate salinity tested enhanced growth under certain high-hydrostatic-pressure and low-temperature conditions, highlighting a synergistic effect on growth for these combined stresses. Phospholipid profiles obtained at 30°C indicated that hydrostatic pressure exerted the dominant control on the degree of lipid saturation, although elevated salinity slightly mitigated the increased degree of lipid unsaturation caused by increased hydrostatic pressure. Profiles of cytosolic and membrane proteins of Halomonas axialensis and H. hydrothermalis performed at 30°C under various salinities and hydrostatic pressure conditions indicated several hydrostatic pressure and salinity effects, including proteins whose expression was induced by either an elevated salinity or hydrostatic pressure, but not by a combination of the two. The interplay between salinity and hydrostatic pressure on microbial growth and physiology suggests that adaptations to hydrostatic pressure and possibly other stresses may partially explain the euryhaline phenotype of members of the genus Halomonas living in deep-sea environments.
doi:10.1128/AEM.70.10.6220-6229.2004
PMCID: PMC522137  PMID: 15466569
23.  A First Record of Obligate Halophilic Aspergilli from the Dead Sea 
Indian Journal of Microbiology  2011;52(1):22-27.
The isolation of obligate halophilic aspergilli from the Dead Sea and the range of salt tolerance of halophilic fungi isolated, are reported here for the first time. The mycobiota of the Dead Sea isolated in this study, was dominated by Aspergillus and Penicillium species; Cladosporium were found in lesser numbers. All three genera were obtained from the water sample; however, Aspergillus was the only genus obtained from the sediment. There was significant difference in growth of each isolate at different salt concentrations and intraspecies analysis revealed dissimilarity in response of strains to different salt concentrations in the growth medium The isolates were euryhaline, with halotolerance up to 20–25% solar salt, Aspergillus and Penicillium species showing a higher level of halotolerance, as compared to that of Cladosporium. Halophilic fungi were found in greater numbers in the sediment sample as compared to that in the water sample. Penicillium and Cladosporium species were exclusively facultative halophiles, while some species of Aspergillus were facultative halophiles. All the obligate halophiles isolated, belonged to the genus Aspergillus and were identified as A. penicillioides and A unguis, the latter being a first record of the species from the Dead Sea.
doi:10.1007/s12088-011-0225-z
PMCID: PMC3298590  PMID: 23449273
Dead Sea; Obligate halophile; Aspergillus; Penicillium; Cladosporium
24.  Anaerobic bacteria from hypersaline environments. 
Microbiological Reviews  1994;58(1):27-38.
Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the Mediterranean French coast in the Rhone Delta, is also described.
PMCID: PMC372951  PMID: 8177169
25.  Diverse Microhabitats Experienced by Halomonas variabilis on Salt-Secreting Leaves 
The leaf surfaces of the salt-excreting tree Tamarix aphylla harbor a wide diversity of halophilic microorganisms, including Halomonas sp., but little is known of the factors that shape community composition in this extreme habitat. We isolated a strain of Halomonas variabilis from the leaf surface of T. aphylla and used it to determine the heterogeneity of salt concentrations experienced by bacteria in this environment. This halophilic strain was transformed with a proU::gfp reporter gene fusion, the fluorescence of which was responsive to NaCl concentrations up to 200 g liter−1. These bioreporting cells were applied to T. aphylla leaves and were subsequently recovered from dew droplets adhering to the leaf surface. Although cells from within a given dew droplet exhibited similar green fluorescent protein fluorescence, the fluorescence intensity varied between droplets and was correlated with the salt concentration measured in each drop. Growth of H. variabilis was observed in all droplets, regardless of the salt concentration. However, cells found in desiccated microniches between dew drops were low in abundance and generally dead. Other bacteria recovered from T. aphylla displayed higher desiccation tolerance than H. variabilis, both in culture and on inoculated plants, despite having lower osmotic tolerance. Thus, the Tamarix leaf surface can be described as a salty desert with occasional oases where water droplets form under humid conditions. While halotolerant bacteria such as Halomonas grow in high concentrations of salt in such wet microniches, other organisms are better suited to survive desiccation in sites that are not wetted.
doi:10.1128/AEM.02791-12
PMCID: PMC3568542  PMID: 23160133

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