Thermoacidophilic Bacterium Research Articles

Precambrian Prokaryotes and Stromatolites

In terms of biochemical and intracellular organization, living systems can be divided into two major “Superkingdoms,” eukaryotes and prokaryotes.Eukaryotes, comprising the more advanced and later evolving Superkingdom, include unicellular or multicellular organisms (viz., members of the Kingdoms Protista, Fungi, Plantae and Animalia) characterized by nucleus-, mitochondrion-, and (in plants and some protists) chloroplast-containing cells that are capable typically of mitotic cell division. Paleontologic evidence indicates that the eukaryotic cell originated during the Middle Proterozoic, probably about 1.4 to 1.5 Ga ago (Schopf and Oehler, 1976).Prokaryotes, comprising the more primitive and earlier evolving Superkingdom, include microbial microorganisms (viz., members of the Kingdom Monera: bacteria, cyanobacteria, archaebacteria, and prochlorophytes) characterized by cells that lack membrane-bound nuclei, mitochondria, chloroplasts, and similar organelles and that reproduce by non-mitotic and non-meiotic division. Some authors (e.g., Woese and Fox, 1977) subdivide prokaryotes (monerans) into two kingdoms, the Kingdom Archaebacteriae (including methanogenic, extremely halophilic and some thermoacidophilic bacteria) and the Kingdom Eubacteriae (including all non-archaebacterial prokaryotes), based on the chemistry of their cell walls, membranes, transfer RNA's and RNA polymerase subunits. Paleontologic evidence indicates that prokaryotes originated early in Earth history - the group was extant, morphologically varied and evidently physiologically advanced at least as early as 3.3 to 3.5 Ga ago (Schopf and Packer, 1987).

Mixed monolayer studies of the interactions of synthetic phosphatidylcholines containing branched fatty acids and a hopane glycolipid isolated from the thermo-acidophilic bacterium bacillus acidocaldarius

Hopanoids, a group of pentacyclic triterpenoids, are widely distributed in eubacterial membranes. In the eubacterium Bacillus acidocaldarius a hopane glycolipid, 1-( O- β- N-acylglucosaminyl)-2,3,4-tetrahydroxypentane-29-hopane, occurs together with phospholipids containing methyl iso- and anteiso-branched fatty acids besides ω-cyclohexane fatty acids. Therefore mixed monolayers of hopane glycolipid (HGL) with 1,2-diisoheptadecanoyl-phosphatidylcholine (DIHPC) and 1,2-dianteisoheptadecanoyl-phosphatidylcholine (DAHPC) were studied. The presence of increasing amounts of HGL in DIHPC films lowers the phase transition midpoint of the liquid-condensed/liquid-expanded transition and at 50 mol% abolishes this transition. In the liquid-expanded state of the DIHPC film, the presence of HGL results in a marked reduction in the mean molecular area occupied by the PC molecules (the condensing effect). The maximum condensation is observed at around 10 mol% HGL while higher concentrations of HGL show no further reduction in the area occupied by the phosphatidylcholine (PC). In the liquid-condensed state of the DIHPC film HGL mixes almost ideally with the PC and no condensation is observed. In liquid-expanded films of DAHPC, HGL also reduces the mean molecular areas of the PC molecules but the magnitude of this reduction increases continually with increasing HGL concentrations. At temperatures where the pure DAHPC film is in the range of the phase transition. HGL condenses the film with molecular area reductions increasing continuously with increasing HGL concentrations. The effects of HGL in liquid-expanded DIHPC monolayers are somewhat smaller than the condensations observed in the presence of cholesterol, while the condensations in DAHPC films almost equals that caused by cholesterol. These results confirm further the cholesterol like role of hopanoids in prokaryotic membranes.

Properties of hopanoids and phosphatidylcholines containing ω-cyclohexane fatty acid in monolayer and liposome experiments

1,2,3,4-Tetrahydroxypentane-29-hopane (THBH) and a glycolipid derived from it are associated with ω-cyclohexane fatty acids-containing lipids in the membrane of Bacillus acidocaldarius. In order to elucidate the function of these lipids we studied mixed monolayer films and compared these with cholesterol-containing films. The hopanoids are able to condense a liquid-expanded film of di-ω-cyclohexyldodecanoylphosphatidylcholine (DCDPC). The condensing effect of THBH is smaller than that of cholesterol. Hopane glycolipid in comparison shows only little condensation. In a more condensed film, at lower temperatures, THBH slightly decreases while hopane glycolipid increases the molecular area. In egg phosphatidylcholine liposomes, 22-hydroxyhopane (diplopterol) and hopane glycolipid reduce the glycerol permeability to a smaller extent than cholesterol. In DCDPC liposomes, the effect of 22-hydroxyhopane is similar to that of cholesterol, while the hopane glycolipid shows only a weak reduction of the permeability. The results demonstrate that hepanoids have a cholesterol-like function in membranes. This function is also discussed in the context of membrane adaptation of a thermoacidophilic bacterium.

Properties of ω-cyclohexane fatty acids in membranes

The properties of di-ω-cyclohexyldodecanoylphosphatidylcholine (DCDPC) in various model membranes were studied by differential scanning calorimetry (DSC) and the monolayer technique. DCDPC shows a broad phase transition at 13°C with a total enthalpy of 4.1 kcal mol as measured by DSC. In a DCDPC monolayer no phase transition was observed. At 25 dyn cm the area increases linearly with temperature. The molecular area at 40°C and 25 dyn cm equals that of dipalmitoylphosphatidylcholine. DCDPC liposome experiments show that the permeability of glycerol is strongly reduced above the phase transition in comparison with linear saturated fatty acid-containing phosphatidylcholines of comparable chain lengths. These results suggest that lipids with ω-cyclohexane fatty acids may possess a high acyl chain density at the free fatty acid end in the core of the membrane, which stabilizes the membrane and influences the permeability. This seems to be an important mechanism for membrane adaptation under various conditions for thermoacidophilic bacteria.

Autotrophic and mixotrophic growth of three thermoacidophilic iron-oxidizing bacteria

Autotrophic and mixotrophic growth of three thermoacidophilic iron-oxidizing bacteria

Autotrophic and mixotrophic growth of three thermoacidophilic iron-oxidizing bacteria

Etude physiologique de 3 souches dont l'une n'a pas encore ete decrite, comparaison avec les Thiobacillus

The effect of temperature and pH on the growth efficiency of the thermoacidophilic bacterium Bacillus acidocaldarius in continuous culture

The molar yield coefficients (Yglucose, YO2) of glucose-limited continuous cultures of the thermoacidophile Bacillus acidocaldarius have been measured as a function of dilution rate as well as over a range of temperature and pH (51°C to 64°C, pH 2.8–5.5) at a fixed dilution rate of approximately 0.1 h-1. The highest growth yields were observed at 51°C and pH>4.3 (Yglucose 54.8 g cells · mol glucose-1, YO2 15.0 g cells · mol O2-1), but were very much lower than those of mesophilic neutrophiles of similar respiratory chain composition to B. acidocaldarius. Even lower growth yields were observed when the temperature was raised or when the pH was lowered, lowest yields occurring at 64°C and pH 2.8 (Yglucose 23.4 g cells · mol glucose-1, YO2 5.9 g cells · mol O2-1).

Thermoproteales: A novel type of extremely thermoacidophilic anaerobic archaebacteria isolated from Icelandic solfataras

Summary Two types of anaerobic extremely thermoacidophilic bacteria have been isolated from more than 50% of the samples collected in solfataric fields throughout Iceland. They both possess highly stable cell envelopes with a characteristic subunit structure, are usually rods of variable length (about 1 to more than 50 μ ) without septa, but can give rise to spheric bodies which exist either attached to the rods or in free state. Under certain conditions, truly branched filaments are frequently observed. The similarities in morphology and growth characteristics indicate that the two types are related to each other. In view of its variable appearance the larger organism (diameter about 0.4 μ m) was called Thermoproteus tenax . Thermoproteus tenax forms H 2 S and CO 2 from elemental sulfur and organic substrates, like glucose, ethanol, malate or formamide. The absence of murein, the presence of polyisoprenoid ether lipids, the complete resistance against the antibiotics rifampicin, streptomycin, vancomycin and chloramphenicol and the component pattern and rifampicin insensitivity of the DNA-dependent RNA polymerase are evidence that Thermoproteus tenax belongs to the archaebacteria. It represents a novel order of the thermoacidophilic branch of this urkingdom.

The effect of growth temperature on the lipids in an extremely thermoacidophilic bacterium, TA-1.

The extreme thermoacidophile TA-1, a Sulfolobus-like organism, was grown at temperatures ranging from 50 to 85°C (at 5°C intervals). The extracted cellular lipids were analysed qualitatively and quantitatively. At temperatures close to the optimum for growth, the levels of glycolipids in total lipid fractions increased. The phospholipid contents were constant except at extremely unfavorable tempertaures for the growth.The alkyl-chains of the total lipid were analysed as alkyl-halide derivatives by gas-liquid chromatography. Usually seven to eight peaks were detected on the chromatogram. By increasing the growth temperature, the areas of peaks which had longer retention periods increased, but those of the shorter ones decreased. These results suggest that the extreme thermoacidophile TA-1 has some mechanisms which alter the membrane properties by changing lipid compositions and their alkyl-chains.

Immobilized bacterial cells containing a thermostable β-galactosidase

A constitutive β-galactosidase has been localized in the cytosol of thermoacidophilic bacterium Caldariella acidophila. Cells have been entrapped in polyacrylamide gel with full retention of enzymic activity; no activity decrease is observed after 8 months of storage. Enzyme properties in entrapped cells are similar to those of the free enzyme. A 73% hydrolysis of lactose has been achieved in a continuous system on a 2 ml entrapped cell column operating at 70°C; half life in these conditions is 30 days.

Gas chromatographic—mass spectrometric analysis of neutral lipids from methanogenic and thermoacidophilic bacteria

The neutral lipids of nine methanogenic and three thermoacidophilic bacteria were analyzed. The major compounds are acyclic isoprenoids in the range of C 15 to C 30. The compounds were identified by means of their mass spectral fragmentation pattern and/or by co-chromatography. A high similarity is seen between the isoprenoid content of the examined bacteria and the distribution of these compounds in ancient sediments and petroleum.

Squalenes, phytanes and other isoprenoids as major neutral lipids of methanogenic and thermoacidophilic “archaebacteria”

The neutral lipids of nine species of methanogenic bacteria including five methanobacilli, two methanococci, a methanospirillum, one methanosarcina as well as two thermoacidophilic bacteria, Thermoplasma and Sulfolobus, were analyzed. The major components were C30, C25 and/or C20 acylic isoprenoid hydrocarbons with a continuous range of hydroisoprenoid homologues. The range of acyclic isoprenoids detected were from C14 to C30. Apart from Methanosarcina barkeri, squalene and/or hydrosqualene derivetives were the predominant components in all species studied. The components of Methanosarcina barkeri were a family of C25 homologues. The distribution of the neutral lipid components and their specific variations in relative intensities emphasized the differences between the test organisms while the generic nature of the isoprenoid hydrocarbons demonstrated similarities between the diverse bacteria. The neutral lipid compositions from these bacteria, many of which exist in environmental conditions like those described for the various evolutionary stages of the archean ecology, resemble the isoprenoid distribution isolated from ancient sediments and petroleum. Therefore, these finding may have major implications to biological and biogeochemical evolution.

Diphytanyl and dibiphytanyl glycerol ether lipids of methanogenic archaebacteria.

The lipids of nine different methanogenic bacterial strains are comprised of diphytanyl glycerol diethers, previously known only in extremely halophilic bacterial, as well as dibiphytanyl diglycerol tetraethers, known formerly only in the extremely thermoacidophilic bacteria Thermoplasma and Sulfolobus. Of the methanogens examined from four representative taxonomic groups, Methanobacterium and Methanospirillum contained both types of isopranyl ethers in nearly equal proportions, whereas the coccal forms, Methanosarcina and Methanococcus, possessed diphytanyl glycerol diethers, but with only a trace of or no dibiphytanyl diglycerol tetraethers. The occurrence of both types of isopranyl glycerol ethers in methanogenic bacteria supports the proposal that they have a close genealogical relationship to the extremely halophilic and thermoacidophilic bacteria.

The biosynthetic pathway of new polyamines in Caldariella acidophila.

1. Spermidine and sym-nor-spermine (1,11-diamino-4,8-diazaundecane) were identified as the major components of the polyamine pool in Caldariella acidophila, an extreme thermoacidophilic bacterium. A minor component, a new polyamine, sym-nor-spermidine (1,7-diamino-4-azaheptane) was isolated and characterized. 2. To elucidate the biosynthetic pathway, labelled methionine, putrescine, spermidine and spermine were fed to Caldariella acidophila. Incubation of the bacterium in the presence of putrescine or spermidine labelled in the tetramethylene moiety gave unlabelled sym-nor-spermidine and sym-nor-spermine, whereas the radioactivity of propylamine-labelled methionine or spermidine was incorporated into these molecules. No radioactivity was recovered in the polyamines pool when spermine was fed to Caldariella acidophila. 3. S-Adenosylmethionine and S-(5'-adenosyl)-3-methylthiopropylamine were identified as intermediates of the biosynthetic pathway; the cellular contents of the two sulphonium compounds, measured with a new isotope-dilution technique, are 60 and 15nmol/g wet wt. of cells respectively. 4. The above results are indicative of a new pathway characterized by three propylamine-transfer reactions, decarboxylated S-adenosylmethionine being the common donor of the propylamine moiety. The reactions yielding sym-nor-spermidine and sym-nor-spermine are reported for the first time. 5. The probable intermediates related to the catabolism of the tetramethylene moiety of spermidine, gamma-aminobutyraldehyde, gamma-aminobutyric acid or Delta(1)-pyrroline were not detectable. Experiments with [3-aminopropyl-3(n)-(3)H]spermidine trihydrochloride plus [tetramethylene-1,4-(14)C]spermidine trihydrochloride gave rise to an amount of labelled CO(2) equivalent to the spermidine catabolized.

Thermophilicity and thermostability of RNA polymerases from two strains of Caldariella acidophila, an extremely thermo-acidophilic bacterium.

Transcription in highly thermophilic microorganisms requires stringent conditions both for the structural stability of RNA polymerase and the conformational state of the DNA template.