Biomedical subjects

A Gambacorta

Publications and source records attributed to A Gambacorta.

At least 19 recordsLinked to original sources

PubMed2006

Desulfurobacterium atlanticum sp. nov., Desulfurobacterium pacificum sp. nov. and Thermovibrio guaymasensis sp. nov., three thermophilic members of the Desulfurobacteriaceae fam. nov., a deep branching lineage within the Bacteria.

Three thermophilic, anaerobic, strictly chemolithoautotrophic, sulphur- and/or thiosulphate-reducing bacteria, designated SL17(T), SL19(T) and SL22(T), were isolated from deep-sea hydrothermal samples collected at 13 degrees N (East Pacific Rise), Guaymas Basin (Gulf of California) and 23 degrees N (Mid-Atlantic Ridge), respectively. These strains differed in their morphology, temperature range and optimum for growth, energy substrates and 16S rRNA gene sequences. The G+C content of the genomic DNA was 41 mol% (SL22(T)), 42 mol% (SL17(T)) and 46 mol% (SL19(T)). Comparative analysis of phenotypic and phylogenetic traits indicated that strains SL17(T) and SL22(T) represented two novel species of the genus Desulfurobacterium and that strain SL19(T) should be considered as a novel species of the genus Thermovibrio. The names Desulfurobacterium pacificum sp. nov. (type strain SL17(T)=DSM 15522(T)=JCM 12127(T)), Desulfurobacterium atlanticum sp. nov. (type strain SL22(T)=DSM 15668(T)=JCM 12129(T)) and Thermovibrio guaymasensis sp. nov. (type strain SL19(T)=DSM 15521(T)=JCM 12128(T)) are proposed for these organisms. Furthermore, phylogenetic data based on 16S rRNA gene sequence analyses correlated with the significant phenotypic differences between members of the lineage encompassing the genera Desulfurobacterium, Thermovibrio and Balnearium and that of the families Aquificaceae and Hydrogenothermaceae. It is therefore proposed that this lineage represents a new family, Desulfurobacteriaceae fam. nov., within the order Aquificales.

Bacterial Typing Techniques↗

PubMed2005

Bipolar tetraether lipids: chain flexibility and membrane polarity gradients from spin-label electron spin resonance.

Membranes of thermophilic Archaea are composed of unique tetraether lipids in which C40, saturated, methyl-branched biphytanyl chains are linked at both ends to polar groups. In this paper, membranes composed of bipolar lipids P2 extracted from the acidothermophile archaeon Sulfolobus solfataricus are studied. The biophysical basis for the membrane formation and thermal stability is investigated by using electron spin resonance (ESR) of spin-labeled lipids. Spectral anisotropy and isotropic hyperfine couplings are used to determine the chain flexibility and polarity gradients, respectively. For comparison, similar measurements have been carried out on aqueous dispersions of diacyl reference lipid dipalmitoyl phosphatidylcholine and also of diphytanoyl phosphatidylcholine, which has methyl-branched chains. At a given temperature, the bolaform lipid chains are more ordered and less flexible than in normal bilayer membranes. Only at elevated temperatures (80 degrees C) does the flexibility of the chain environment in tetraether lipid assemblies approach that of fluid bilayer membranes. The height of the hydrophobic barrier formed by a monolayer of archaebacterial lipids is similar to that in conventional fluid bilayer membranes, and the permeability barrier width is comparable to that formed by a bilayer of C16 lipid chains. At a mole ratio of 1:2, the tetraether P2 lipids mix well with dipalmitoyl phosphatidylcholine lipids and stabilize conventional bilayer membranes. The biological as well as the biotechnological relevance of the results is discussed.

Electron Spin Resonance Spectroscopy↗

PubMed2004

Polysaccharides from extremophilic microorganisms.

Several marine thermophilic strains were analyzed for exopolysaccharide production. The screening process revealed that a significant number of thermophilic microorganisms were able to produce biopolymers, and some of them also revealed interesting chemical compositions. We have identified four new polysaccharides from thermophilic marine bacteria, with complex primary structures and with different repetitive units: a galacto-mannane type from strain number 4004 and mannane type for the other strains. The thermophilic Bacillus thermantarcticus produces two exocellular polysaccharides (EPS 1, EPS 2) that give the colonies a typical mucous character. The exopolysaccharide fraction was produced with all substrates assayed, although a higher yield 400 mg liter(-1) was obtained with mannose as carbon and energy source. NMR spectra confirmed that EPS 1 was a heteropolysaccharide of which the repeating unit was constituted by four different alpha-D-mannoses and three different beta-D-glucoses. It seems to be close to some xantan polymers. EPS 2 was a mannan. Four different alpha-D-mannoses were found as the repeating unit. Production and chemical studies of biopolymers produced by halophilic archaea, Haloarcula species were also reported.

Bacillus↗

PubMed2003

Production of exopolysaccharides from a thermophilic microorganism isolated from a marine hot spring in flegrean areas.

A thermophilic strain isolated from sea sand at Maronti, near Sant' Angelo (Ischia), is described. The organism grows well at an optimal temperature of 60 degrees C at pH 7.0. The thermophilic bacterium, named strain 4004, produces an exocellular polysaccharide (EPS) in yields of 90 mg/l. The EPS fraction was produced with all substrates tested, although a higher yield was obtained with sucrose or trehalose as sole carbon source. During growth, the EPS content was proportional to the biomass. Three fractions (EPS1, EPS2, EPS3) were obtained after purification. Quantitative monosaccharide analysis of the EPSs revealed the presence of mannose:glucose:galactose in a relative ratio of 0.5:1.0:0.3 in EPS1, mannose:glucose:galactose in a relative ratio of 1.0:0.3:trace in EPS2, and galactose:mannose:glucosamine:arabinose in a relative ratio of 1.0:0.8:0.4:0.2 in EPS3. The average molecular mass of EPS3 was determined to be 1x10(6) Da. From comparison of the chemical shift values in (1)H and (13)C spectra, we conclude that EPS3 presents a pentasaccharide repeating unit.

Bacillaceae↗

PubMed2001

Purification and characterization of thermostable xylose(glucose) isomerase from Bacillus thermoantarcticus.

Xylose isomerase produced by Bacillus thermoantarcticus was purified 73-fold to homogeneity and its biochemical properties were determined. It was a homotetramer with a native molecular mass of 200 kDa and a subunit molecular mass of 47 kDa, with an isoelectric point at 4.8. The enzyme had a K(m) of 33 mM for xylose and also accepted D-glucose as substrate. Arrhenius plots of the enzyme activity of xylose isomerase were linear up to a temperature of 85 degrees C. Its optimum pH was around 7.0, and it had 80% of its maximum activity at pH 6.0. This enzyme required divalent cations for its activity and thermal stability. Mn(2+), Co(2+) or Mg(2+) were of comparable efficiency for xylose isomerase reaction, while Mg(2+) was necessary for glucose isomerase reaction.

Aldose-Ketose Isomerases↗

PubMed2001

Accumulation of osmoprotectants and lipid pattern modulation in response to growth conditions by Halomonas pantelleriense.

The effects of salinity, growth temperature, pH and composition of the medium on the accumulation of intracellular organic solutes, by nuclear magnetic resonance spectroscopy (NMR) in Halomonas pantelleriense were examined. The modulation of lipid pattern in different growth conditions was also reported. H. pantelleriense accumulated glycine betaine, ectoine, hydroxyectoine and glutamate. The type of osmoprotectant and the relative proportion depended on growth conditions. The main lipids identified by NMR studies were 1,2 diacylglycero-3-phosphorylethanolamine (PEA), 1,2 diacylglycero-3-phosphoryl-glycerol (PG) and cardiolipin, (DPG). The predominant fatty acids were C16:0 and C18:1, minor fatty acids were C16:1 and C18:0. The relative percentage of polar lipids and fatty acids were affected by growth conditions.

Halomonas↗

PubMed2000

Comparison of the ADP-ribosylating thermozyme from Sulfolobus solfataricus and the mesophilic poly(ADP-ribose) polymerases.

The poly(ADP-ribose) polymerase-like thermozyme purified from Sulfolobus solfataricus was characterised with respect to some physico-chemical properties. The archaeal protein exhibited a scarce electrophoretic mobility at both pH 2.9 and pH 7.5. Determination of the isoelectric point (pI=7.0-7.2) allowed us to understand the reason for the limited migration at pH 7.5, while amino acid composition analysis showed a moderate content of basic residues, which reduced mobility at pH 2.9. With respect to the charge, the archaeal enzyme behaved differently from the eukaryotic thermolabile poly(ADP-ribose) polymerase, described as a basic protein (pI=9.5). Well known inhibitors of the mesophilic polymerase like Zn(2+), nicotinamide and 3-aminobenzamide exerted a smaller effect on the enzyme from S. solfataricus, reducing the activity by at most 50%. Mg(2+) was a positive effector, although in a dose-dependent manner. It influenced the fluorescence spectrum of the archaeal protein, whereas NaCl had no effect.

Amino Acids↗

PubMed2000

Lipid profile: a useful chemotaxonomic marker for classification of a new cyanobacterium in Spirulina genus.

The morphological, physiological and genetic characteristics of an isolate cyanobacterium from hard sand of the lake Venere in the Pantelleria island (Italy) were described. The isolate with a small-size coiled helix shape, growing optimally at pH 9.2-9.5 at 30 degrees C under continuous illumination and aeration, possessed a 61.5 mol% of Guanine + Cytosine content of DNA. The lipid profile showed the presence of mono-, di-glycosyl, sulphoquinovolosyl and phosphatidyl (MGDG, DGDG, SQDG and PG). The fatty acid profile was also studied, characterized by the absence of gamma-linolenic acid and the presence of saturated and monounsaturated C16 and C18. The latter was also present as a dienoic component. The fatty acid composition was affected by growth temperature by increasing the degree of desaturation at a lower temperature and the biosynthesis of shorter acyl chains. The effects of growth conditions other than temperature, physical, nutritional and chemical on lipid composition were also studied. The overall features of the cyanobacterium isolated from Pantelleria clustered it into Spirulina genus.

Base Composition↗

PubMed2000

A thermophilic Bacillus isolated from an Eolian shallow hydrothermal vent, able to produce exopolysaccharides.

A thermophilic aerobic microorganism, able to produce two exocellular polysaccharides (EPS1 and EPS2), was isolated from a shallow hydrothermal vent at Vulcano island (Eolian Islands, Italy). EPS1 and EPS2 were based on mannose and glucose although in a different ratio. EPS2 possessed a trisaccharide repeating unit with a manno-pyranoside configuration. New isolate phenotype was studied by physiological and morphological observations, including biochemical and antimicrobial susceptibility tests (134). Previous analyses carried out on 87 field isolates and 8 thermophilic reference bacilli displayed low phenotypic similarity level (S(SM) = 65%) with Bacillus thermodenitrificans DSM 465. Optimal growth occurs at 65 degrees C and pH 7.0. Oxidase and catalase are negative. The guanine-plus-cytosine (G+C) content of DNA is 52.7%. Genotypic investigations demonstrated the diversity of the isolate with fifteen selected thermophilic Bacillus spp. when we compared the restriction patterns of the amplified 16S rDNA. The membrane lipids are based on fatty acids mainly belonging to the iso-family.

Bacillus↗

PubMed2000

Effects of hydrostatic pressure and temperature on physiological traits of Thermococcus guaymasensis and Thermococcus aggregans growing on starch.

The effects of temperature and hydrostatic pressure on growth of two novel Thermococcus species, T. guaymasensis and T. aggregans, were investigated. These archaea, isolated from the Guaymas Basin hydrothermal vent site at 2000 meters depth, are able to grow on starch in sulfur-depleted medium producing significant amounts of amylases and pullulanases. At 85 degrees C, T. guaymasensis exhibited a barophilic response at 20 and 35 MPa but inhibition of growth occurred at 50 MPa; at 50 MPa, cell replication was repressed, the mean cell size increased, and production of starch-hydrolysing enzymes was significantly stimulated. Barophily was also expressed by T. guaymasensis under 20 MPa at sub-optimal temperature (70 C) but morphological alterations of cells were observed earlier (35 MPa). No barophily was exhibited by T. aggregans at 85 degrees C. In this case, cell replication was repressed at 20 MPa and remarkable inhibition of growth occurred at 50 MPa. Only when T. aggregans was cultivated at 75 degrees C, a significant barophilic response was exhibited at 20 MPa, as shown by the rate of replication and metabolism. These results show that Thermococcus species, although isolated from the same ecosystem, differ with regard to the effects of pressure and temperature on cell physiology. The metabolic responses and their significance for potential biotechnological applications are also discussed.

Amylases↗

PubMed2000

Purification of the ADP-ribosylating enzyme from S. solfataricus by SDS-polyacrylamide gel electrophoresis and electroelution.

The ADPribosylating enzyme from the thermophilic archaeon S. solfataricus was purified by a simple procedure which included preparative electrophoresis on a 0.1% SDS- polyacrylamide gel. The gel slice containing the enzymatic protein was cut out and the enzyme was solubilized by electroelution. The pure enzyme was obtained by chromatography of the electroeluted sample on a DNA-Sepharose column. The purified enzyme retained both its full activity and the structuring ability as a function of temperature increase.

Archaeal Proteins↗

PubMed1999

Thermococcus barophilus sp. nov., a new barophilic and hyperthermophilic archaeon isolated under high hydrostatic pressure from a deep-sea hydrothermal vent.

A novel barophilic, hyperthermophilic, anaerobic sulfur-metabolizing archaeon, strain MPT (T = type strain), was isolated from a hydrothermal vent site (Snakepit) on the Mid-Atlantic Ridge (depth, 3550 m). Enrichments and isolation were done under 40 MPa hydrostatic pressure at 95 degrees C. Strain MPT was barophilic at 75, 80, 85, 90, 95 and 98 degrees C, and was an obligate barophile between 95 and 100 degrees C (Tmax). For growth above 95 degrees C, a pressure of 15.0-17.5 MPa was required. The strain grew at 48-95 degrees C under atmospheric pressure. The optimal temperature for growth was 85 degrees C at both high (40 MPa) and low (0.3 MPa) pressures. The growth rate was twofold higher at 85 degrees C under in situ hydrostatic pressure compared to at low pressure. Strain MPT cells were motile, coccoid, 0.8-2.0 microns in diameter and covered by a hexagonal S-layer lattice. The optimum pH and NaCl concentration for growth at low pressure were 7.0 and 20-30 g l-1, respectively. The new isolate was an obligate heterotroph and utilized yeast extract, beef extract and peptone for growth. Growth was optimal in the presence of elemental sulfur. Rifampicin and chloramphenicol inhibited growth. The core lipids consisted of a major archaeol and a complex lipid pattern consisting of a major phospholipid. The DNA G + C content was 37.1 mol%. Sequencing of the 16S rRNA gene revealed that strain MPT belonged to the genus Thermococcus and it is proposed that this isolate should be designated as a new species, Thermococcus barophilus.

Atlantic Ocean↗

PubMed1999

Isolation and biological characterization of 3(2H)-isoflavene-resistant and -dependent poliovirus type 2 Sabin mutants.

Poliovirus type 2 Sabin mutants were selected for drug resistance and dependence by plating on HeLa cell monolayers in the presence of 3(2H)-isoflavene, a compound related to dichloroflavan, which prevents the shut-off of host translation and poliovirus RNA and protein synthesis. The drug-resistant mutants grew equally well in the presence and in the absence of the drug, while the drug-dependent mutants only grew in the presence of the compound. One dependent and one resistant mutant were characterized biologically in more detail. The resistant mutant did not exhibit thermolability. The mild thermolability exhibited by the dependent mutant was not affected by the addition of 3(2H)-isoflavene, indicating that the substance does not bind the poliovirus type 2 Sabin capsid. The translation of viral proteins and the shut-off of host protein translation during cell infection were not inhibited in either mutant. In the absence of the drug, the cleavage of the precursor VPO, a step in virus protein processing, was affected in the dependent mutant. The dependence of the mutant on the drug was due to the inability of 75S empty particles to reach maturation: our results strongly suggest that this phenomenon is strictly dependent on the reduction of RNA synthesis, confirming the existence of a dynamic equilibrium between RNA production and genome encapsidation during the poliovirus replication cycle.

Antiviral Agents↗

PubMed1999

Identification and sequencing of beta-myrcene catabolism genes from Pseudomonas sp. strain M1.

The M1 strain, able to grow on beta-myrcene as the sole carbon and energy source, was isolated by an enrichment culture and identified as a Pseudomonas sp. One beta-myrcene-negative mutant, called N22, obtained by transposon mutagenesis, accumulated (E)-2-methyl-6-methylen-2,7-octadien-1-ol (or myrcen-8-ol) as a unique beta-myrcene biotransformation product. This compound was identified by gas chromatography-mass spectrometry. We cloned and sequenced the DNA regions flanking the transposon and used these fragments to identify the M1 genomic library clones containing the wild-type copy of the interrupted gene. One of the selected cosmids, containing a 22-kb genomic insert, was able to complement the N22 mutant for growth on beta-myrcene. A 5,370-bp-long sequence spanning the region interrupted by the transposon in the mutant was determined. We identified four open reading frames, named myrA, myrB, myrC, and myrD, which can potentially code for an aldehyde dehydrogenase, an alcohol dehydrogenase, an acyl-coenzyme A (CoA) synthetase, and an enoyl-CoA hydratase, respectively. myrA, myrB, and myrC are likely organized in an operon, since they are separated by only 19 and 36 nucleotides (nt), respectively, and no promoter-like sequences have been found in these regions. The myrD gene starts 224 nt upstream of myrA and is divergently transcribed. The myrB sequence was found to be completely identical to the one flanking the transposon in the mutant. Therefore, we could ascertain that the transposon had been inserted inside the myrB gene, in complete agreement with the accumulation of (E)-2-methyl-6-methylen-2,7-octadien-1-ol by the mutant. Based on sequence and biotransformation data, we propose a pathway for beta-myrcene catabolism in Pseudomonas sp. strain M1.

Acyclic Monoterpenes↗

PubMed1998

Purification and biochemical characterization of a poly(ADP-ribose) polymerase-like enzyme from the thermophilic archaeon Sulfolobus solfataricus.

A poly(ADP-ribose) polymerase-like enzyme, detected in a crude homogenate from Sulfolobus solfataricus by means of activity and immunoblot analyses, was purified to electrophoretic homogeneity by a rapid procedure including two sequential affinity chromatographies, on NAD+-agarose and DNA-Sepharose. The latter column selected specifically the poly(ADP-ribosyl)ating enzyme with a 17% recovery of enzymic activity and a purification of more than 15000-fold. The molecular mass (54-55 kDa) assessed by SDS/PAGE and immunoblot was definitely lower than that determined for the corresponding eukaryotic protein. The enzyme was proved to be thermophilic, with a temperature optimum of approx. 80 degreesC, and thermostable, with a half-life of 204 min at 80 degreesC, in good agreement with the requirements of a thermozyme. It displayed a Km towards NAD+ of 154+/-50 microM; in the pH range 6.5-10.0 the activity values were similar, not showing a real optimum pH. The enzyme was able to bind homologous DNA, as evidenced by the ethidium bromide displacement assay. The product of the ADP-ribosylating reaction co-migrated with the short oligomers of ADP-ribose (less than 6 residues) from a eukaryotic source. Reverse-phase HPLC analysis of the products, after digestion with phosphodiesterase I, gave an elution profile reproducing that obtained by the enzymic digestion of the rat testis poly(ADP-ribose). These results strongly suggest that the activities of the purified enzyme include the elongation step.

Animals↗

PubMed1998

Desulfurobacterium thermolithotrophum gen. nov., sp. nov., a novel autotrophic, sulphur-reducing bacterium isolated from a deep-sea hydrothermal vent.

A thermophilic, anaerobic, strictly autotrophic, sulphur-reducing bacterium, designated BSAT (T = type strain), was isolated from a deep-sea hydrothermal chimney sample collected at the mid-Atlantic ridge. Gram-negative cells occurred singly or in pairs as small highly motile rods. Spores were not observed. The temperature range for growth was 40 to 75 degrees C, with an optimum at 70 degrees C. The pH range for growth at 70 degrees C was from 4.4 to 7.5, with an optimum around 6.0. The sea salt concentration range for growth was 15-70 gI(-1) with an optimum at 35 gI(-1). Elemental sulphur, thiosulphate and sulphite were reduced to hydrogen sulphide. Sulphate and cystine were not reduced. The G+C content of the genomic DNA was 35 mol%. Phylogenetic analyses of the 16S rRNA gene indicated that the strain was a member of the domain Bacteria and formed a branch that was almost equidistant from members of the orders Aquificales and Thermotogales. The new organism possesses phenotypic and phylogenetic traits that do not allow its classification as a member of any previously described genus; therefore, it is proposed that this isolate should be described as a member of a novel species of a new genus, Desulfurobacterium gen. nov., of which Desulfurobacterium thermolithotrophum sp. nov. is the type species. The type strain is BSAT (= DMS 11699T).

Base Sequence↗

PubMed1998

Thermococcus guaymasensis sp. nov. and Thermococcus aggregans sp. nov., two novel thermophilic archaea isolated from the Guaymas Basin hydrothermal vent site.

Thermococcus strains TYST and TYT isolated from the Guaymas Basin hydrothermal vent site and previously described were compared by DNA-DNA hybridization analysis with the closest Thermococcus species in terms of physiology and nutritional aspects. On the basis of the new data and taking into consideration the molecular, physiological and morphological traits published previously, it is proposed that strains TYT and TYST should be classified as new species named Thermococcus aggregans sp. nov. and Thermococcus guaymasensis sp. nov., respectively. The type strain of T. aggregans is strain TYT (= DSM 10597T) and the type strain of T. guaymasensis is strain TYST (= DSM 11113T).

DNA, Archaeal↗

PubMed1997

ADPribosylation reaction by free ADPribose in Sulfolobus solfataricus, a thermophilic archaeon.

In the archaeon Sulfolobus solfataricus, protein ADPribosylation by free ADPribose was demonstrated by testing both [adenine-14C(U)]ADPR and [adenine-14C(U)]NAD as substrates. The occurrence of this process was shown by using specific experimental conditions. Increasing the incubation time and lowering the pH of the reaction mixture enhanced the protein glycation by free ADPribose. At pH 7.5 and 10 min incubation, the incorporation of free ADPribose into proteins was highly reduced. Under these conditions, the autoradiographic pattern showed that, among the targets of ADPribose electrophoresed after incubation with 32P-NAD, the proteins modified by free 32P-ADPribose mostly corresponded to high molecular mass components. Among the compounds known to inhibit the eukaryotic poly-ADPribose polymerase, only ZnCl2 highly reduced the ADPribose incorporation from NAD into the ammonium sulphate precipitate. A 20% inhibition was measured in the presence of nicotinamide or 3-aminobenzamide. No inhibition was observed replacing NAD with ADPR as substrate.

Adenosine Diphosphate Ribose↗