A bacterium-based contact assay for evaluating the quality of solid samples-Results from an international ring-test.

The contact assay measuring the inhibition of Arthrobacter globiformis dehydrogenase activity as an endpoint to evaluate the toxicity of solid samples was tested in an international ring-test to validate its performance for ISO standardization (ISO/CD 18187). This work reports the results of the ring-test involving 9 laboratories from six countries. At least 8 valid data sets were obtained for each sample and more than three quarters of the participants attained the validity criteria defined in the standard.

Isolation and characterization of an isoproturon mineralizing Sphingomonas sp. strain SH from a French agricultural soil.

The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an agricultural soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp.

Molecular analysis of the catechol-degrading bacterial community in a coal wasteland heavily contaminated with PAHs.

A PCR-based molecular tool was developed to estimate the diversity of the catechol-degrading bacterial community in a coal wasteland heavily contaminated with PAHS. A degenerate primer pair specific to catA sequences was designed by multiple alignment of known sequences coding a key intermediate of the beta-ketoadiapate pathway degrading catechol, namely catechol 1,2-dioxygenase. The specificity of this primer pair was assessed in 21 pure strains by PCR and sequencing.

Detection and organization of atrazine-degrading genetic potential of seventeen bacterial isolates belonging to divergent taxa indicate a recent common origin of their catabolic functions.

A collection of 17 atrazine-degrading bacteria isolated from soils was studied to determine the composition of the atrazine-degrading genetic potential (i.e. trzN, trzD and atz) and the presence of IS1071.

pcaH, a molecular marker for estimating the diversity of the protocatechuate-degrading bacterial community in the soil environment.

Microorganisms degrading phenolic compounds play an important role in soil carbon cycling as well as in pesticide degradation. The pcaH gene encoding a key ring-cleaving enzyme of the beta-ketoadipate pathway was selected as a functional marker. Using a degenerate primer pair, pcaH fragments were cloned from two agricultural soils.