Reduction of chromate,selenite, tellurite,and iron (III) by the moderately thermophilic bacterium <Emphasis Type="Italic">Bacillus thermoamylovorans</Emphasis> SKC1

A moderately thermophilic, facultatively anaerobic bacterium capable of reducing Cr(VI) (strain SKC1) was isolated from municipal sewage. Based on the analysis of the 16S rRNA gene nucleotide sequence and DNA-DNA hybridization data, strain SKC1 was identified as a representative of the species Bacillus thermoamylovorans. B. thermoamylovorans SKC1 is capable of reducing chromate with L-arabinose as an electron donor with an optimum at 50°C and neutral pH. The culture is able to reduce Cr(VI) at its initial concentration in the medium of up to 150 mg/l. In addition to chromate, strain SKC1 is capable of reducing selenite and tellurite, as well as soluble forms of Fe(III). It was shown that Cr(VI), Te(IV), and Se(IV) exert a bacteriostatic effect on strain SKC1, and the reduction of these anions performs the detoxification function. This is the first communication on the reduction of chromate, selenite, tellurite, and soluble Fe(III) species by a culture of thermophilic bacilli.     

Retromobilization of heavy metal resistance genes in unpolluted and heavy metal polluted soil

Abstract: Retromobilization of the nonconjugative (Tra⁻Mob⁺) IncQ vector, pMOL155, and the non-mobilizable (Tra⁻Mob⁻) vector, pMOL149, by means of the IncP plasmids RP4 and pULB113 (RP4::Mu3A), was studied in plate matings and in soil microcosms, and compared with direct and triparental mobilization. Both vectors harbour the czc genes, originating from Alcaligenes eutrophus , which code for resistance to Co, Zn, and Cd. The donor of the czc genes was Escherichia coli which did not express these genes. The recipient, Alcaligenes eutrophus , expressed the czc genes very well. Retromobilization, direct and triparental mobilization of pMOL155 was observed in sterile soil. Both the addition of nutrients and heavy metals significantly enhanced the number of (retro)transconjugants. Retromobilization was also detected in nutrient amended nonsterile soil, but the presence of the autochthonous soil biota strongly reduced the number of retrotransconjugants and also prevented their increase upon application of heavy metals to the soil. Retromobilization of the czc genes, cloned in pMOL149, by using pULB113 was also observed, yet only in sterile, nutrient amended, heavy metal polluted soil.     

Biodiversity of Thermophilic Prokaryotes with Hydrolytic Activities in Hot Springs of Uzon Caldera, Kamchatka (Russia)

Samples of water from the hot springs of Uzon Caldera with temperatures from 68 to 87°C and pHs of 4.1 to 7.0, supplemented with proteinaceous (albumin, casein, or α- or β-keratin) or carbohydrate (cellulose, carboxymethyl cellulose, chitin, or agarose) biological polymers, were filled with thermal water and incubated at the same sites, with the contents of the tubes freely accessible to the hydrothermal fluid. As a result, several enrichment cultures growing in situ on different polymeric substrates were obtained. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments obtained after PCR with Bacteria-specific primers showed that the bacterial communities developing on carbohydrates included the genera Caldicellulosiruptor and Dictyoglomus and that those developing on proteins contained members of the Thermotogales order. DGGE analysis performed after PCR with Archaea- and Crenarchaeota-specific primers showed that archaea related to uncultured environmental clones, particularly those of the Crenarchaeota phylum, were present in both carbohydrate- and protein-degrading communities. Five isolates obtained from in situ enrichments or corresponding natural samples of water and sediments represented the bacterial genera Dictyoglomus and Caldanaerobacter as well as new archaea of the Crenarchaeota phylum. Thus, in situ enrichment and consequent isolation showed the diversity of thermophilic prokaryotes competing for biopolymers in microbial communities of terrestrial hot springs.     

PCR-Based Identification of Hyperthermophilic Archaea of the Family Thermococcaceae

A method for rapid detection and identification of hyperthermophilic archaea of the family Thermococcaceae based on PCR amplification of 16S rRNA gene fragments with primers TcPc 173F (5′-TCCCCCATAGGYCTGRGGTACTGGAAGGTC-3′) and TcPc 589R (5′-GCCGTGRGATTTCGCCAGGGACTTACGGGC-3′) was developed and used for identification of new isolates.     

Moorella sulfitireducens sp. nov., a thermophilic anaerobic bacterium isolated from a terrestrial thermal spring

Extremophiles - The haloalkaliphilic genus Thioalkalivibrio, widely used in bio-desulfurization, can oxidize H2S to So, which is excreted outside cells in the form of biosulfur globules. As...     

Isolation and characterization of thermostable DNA polymerase of the hyperthermophilic archaeum <Emphasis Type="Italic">Thermococcus litoralis</Emphasis> Sh1AM

Overall, 30 strains of hyperthermophilic archaea, representing seven species of the genera Thermococcus, Desulfurococcus, Thermoproteus, and Acidilobus, were tested for the presence of thermostable DNA polymerases. Thermostabilities of the polymerases varied distinctly among the strains within one species. Polymerases of five strains retained 60–100% activity upon incubation of the preparations at 95°C for 120 min. A new DNA polymerase was isolated from the strain Thermococcus litoralis Sh1AM, possessing the enzyme with the most promising properties, and characterized. Molecular weight of the enzyme is 90–100% kDa. The purified DNA polymerase preserved 50% of the initial activity upon incubation at 95°C for 120 min. The polymerase isolated displayed an associated 3–5 exonuclease activity. The error rate when extending a DNA strand was at least twofold lower compared with Taq polymerase. The main physicochemical and enzymatic properties of the new polymerase are similar to the known DNA polymerases of family B.Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 1, 2005, pp. 40–47.Original Russian Text Copyright © 2005 by Slobodkina, Chernykh, Lopatin, Ilina, Bannikova, Ankenbauer, Eldarov, Varlamov, Bonch-Osmolovskaya.     

Thermophilic prokaryotes from deep subterranean habitats

The deep continental biosphere consists of geologically isolated ecosystems differing in their physicochemical, geological, and trophic parameters. Most of the deep ecosystems exist at elevated temperatures (50–120°C), which favor the development of thermophilic microorganisms. In many cases, the indigenous nature of subsurface microorganisms is questionable due to problems of collecting representative and non-contaminated samples. In spite of the numerous studies on the deep biosphere microbial communities, the number of cultivated thermophiles isolated from subsurface environments not associated with petroleum deposits does not exceed 30 species. More than half of the thermophilic species isolated from deep subsurface belong to the Firmicutes. The majority of the underground thermophiles are represented by strict or facultative anaerobes, with capacity for sulfate and iron reduction notably widespread. Most thermophilic subsurface microorganisms are organotrophs, although chemolithoautotrophic thermophiles also have been reported. This review deals with the phylogenetic diversity and physiological properties of the cultivated thermophilic prokaryotes isolated from various deep subterranean habitats.     

Detection of a Culturable Hyperthermophilic Archaeon of the Genus Sulfophobococcus in an Anaerobic Digestor Operated in a Thermophilic Regime

A stable association of hyperthermophilic microorganisms (82°C), which contained mostly cocci and a minor amount of non-spore-forming rods, was obtained from the digested sludge of an anaerobic digestor used to process municipal wastewater under thermophilic conditions (50°C). PCR amplification of 16S rRNA genes using total DNA isolated from this association and archaea-specific primers, followed by sequencing of the product obtained, showed that the archaeal component was represented by a single nucleotide sequence, which was 99.9% homologous to the 16S rRNA gene of Sulfophobococcus zilligii. Thus, a hyperthermophilic archaeon was for the first time detected in a system of anaerobic biological treatment of wastewater. In addition, this is the first report on the detection of a culturable member of Crenarchaeota in anthropogenic habitats with neutral pH.