Carboxydothermus siderophilus sp. nov., a thermophilic, hydrogenogenic, carboxydotrophic, dissimilatory Fe(III)-reducing bacterium from a Kamchatka hot spring.

A novel anaerobic, thermophilic, Fe(III)-reducing, CO-utilizing bacterium, strain 1315(T), was isolated from a hot spring of Geyser Valley on the Kamchatka Peninsula. Cells of the new isolate were Gram-positive, short rods. Growth was observed at 52-70 degrees C, with an optimum at 65 degrees C, and at pH 5.5-8.5, with an optimum at pH 6.5-7.2. In the presence of Fe(III) or 9,10-anthraquinone 2,6-disulfonate (AQDS), the bacterium was capable of growth with CO and yeast extract (0.2 g l(-1)); during growth under these conditions, strain 1315(T) produced H(2) and CO(2) and Fe(II) or AQDSH(2), respectively. Strain 1315(T) also grew by oxidation of yeast extract, glucose, xylose or lactate under a N(2) atmosphere, reducing Fe(III) or AQDS. Yeast extract (0.2 g l(-1)) was required for growth. Isolate 1315(T) grew exclusively with Fe(III) or AQDS as an electron acceptor. The generation time under optimal conditions with CO as growth substrate was 9.3 h. The G+C content of the DNA was 41.5+/-0.5 mol%. 16S rRNA gene sequence analysis placed the organism in the genus Carboxydothermus (97.8 % similarity with the closest relative). On the basis of physiological features and phylogenetic analysis, it is proposed that strain 1315(T) should be assigned to a novel species, Carboxydothermus siderophilus sp. nov., with the type strain 1315(T) (=VKPM 9905B(T) =VKM B-2474(T) =DSM 21278(T)).

Ammonifex thiophilus sp. nov., a hyperthermophilic anaerobic bacterium from a Kamchatka hot spring.

A novel anaerobic, extremely thermophilic, facultatively chemolithoautotrophic bacterium designated strain SR(T) was isolated from a terrestrial hot spring in Kamchatka (Russia). The cells of the novel strain were spore-forming rods with a Gram-positive type of cell wall. The novel isolate grew at 60-82 degrees C (optimum 75 degrees C) and pH 6.0-7.5 (optimum 6.8). Molecular hydrogen and formate were used as electron donors. Thiosulfate, sulfate or elemental sulfur served as electron acceptors yielding hydrogen sulfide. No growth was observed on either substrate in the presence of nitrate as the electron acceptor. The G+C content of the DNA was 56.2 mol%. Phylogenetic analyses of the 16S rRNA gene showed that strain SR(T) was most closely related to Ammonifex degensii (96.4 % gene sequence similarity). However, the novel isolate possessed phenotypic characteristics that differed significantly from those of A. degensii, the only other recognized species of the genus Ammonifex. It is concluded that strain SR(T) (=DSM 19636(T)=VKM B-2461(T)) represents the type strain of a novel species of the genus Ammonifex, for which the name Ammonifex thiophilus sp. nov. is proposed. An emendation of the genus Ammonifex is proposed based on the phenotypic characteristics of the novel species.

Two-dimensional paracrystalline glycoprotein S-layers as a novel matrix for the immobilization of human IgG and their use as microparticles in immunoassays.

In the present study, cup-shaped 1-3 microns large cell wall fragments from Thermoanaerobacter thermohydrosulfuricus L111-69 covered with a hexagonal S-layer lattice composed of glycoprotein subunits were shown to act as a matrix for the immobilization of human IgG. After cross-linking the S-layer glycoprotein lattice with glutaraldehyde (S-layer microparticles), IgG was either bound to carbodiimide activated carboxyl groups from acidic amino acids from the protein moiety or to the carbohydrate chains activated with cyanogen bromide or oxidized with periodate. After determining the binding capacity of the S-layer lattice for human IgG, the orientation of the immobilized antibody molecules was investigated using anti-human IgG peroxidase conjugates with different specificity. Attachment of S-layer microparticles with covalently bound human IgG to microplates precoated with anti-human IgG of different specificity led to clear correlations between the amount of applied human IgG and the absorption values in the immunoassays. The steepest absorption curves were obtained when human IgG was bound to the carbohydrate chains exposed on the surface of the S-layer lattice. This confirmed that the location and the accessibility of the immobilized antibodies on S-layer microparticles is of major importance for the response in immunoassays. In addition to the high reproducibility of the amount of IgG which could be bound to the S-layer lattice and the high reproducibility of the absorption curves in the immunoassays, one major advantage of using cup-shaped S-layer microparticles can be seen in the considerable increase of the actual surface available for binding processes and immunological reactions.