Philippe Baranger | PubMed Health

PubMed2006

A nonlinear parametric model for phenanthrene sorption.

Two models for phenanthrene sorption prediction are discussed and checked against experimental data. The first model, based on a two-site Langmuir expression, displays too large uncertainties. The second is based on a modified Langmuir relation and provides a better description of the whole dataset. It includes an experimentally derived relation between the site maximal concentration and chemical parameters of the substrate: TOC amount and polarity index (O+N)/C. The model is tested against sorption isotherms of phenanthrene acquired with six different substrates. Calculated values display satisfying accordance with experimental data. Validity of the model is tested with an isotherm that does not belong to the set of data used for the regression, with good results. Some discrepancies may arise from analytical uncertainty and structural aspects not included within the model.

Journal Article↗

PubMed2005

Oxidation of arsenite by Thiomonas strains and characterization of Thiomonas arsenivorans sp. nov.

A novel bacterium, strain b6(T) (T=type strain), was isolated from a disused mine site by growth using arsenite [As(III)] as energy source in a simple mineral medium. Cells of strain b6(T) were rod-shaped, Gram-negative, non-sporulating and motile. Optimum growth occurred at temperatures between 20 and 30 degrees C, and at pH between 4.0 and 7.5. Strain b6(T) grew chemoautotrophically on As(III), sulphur and thiosulphate, and also heterotrophically on yeast extract and a variety of defined organic compounds. Several other Thiomonas strains, including the type species Thiomonas (Tm.) intermedia, were able to oxidize As(III), though only strain b6(T) and strain NO115 could grow using As(III) as sole energy source in the absence of any organic compound. The G+C content of the DNA of strain b6(T) was 65.1 mol %. Comparative small subunit (SSU) ribosomal RNA (rRNA) analysis indicated that strain b6(T) belongs to the genus Thiomonas in the beta-subdivision of the Proteobacteria. It was closely related to an unnamed Thiomonas strain (NO115) isolated from a Norwegian mining site, though sequence identities between strain b6(T) and characterized Thiomonas species were less than 95%. DNA-DNA hybridization between strain b6(T) and the type species of the genus Tm. intermedia showed less than 50% homology. On the basis of phylogenetic and phenotypic characteristics, strain b6(T) (DSM 16361(T), LMG 22795(T)) is proposed as the type strain of the new species Thiomonas arsenivorans, sp. nov.

Arsenites↗