Degradation of o-xylene and m-xylene by a novel sulfate-reducer belonging to the genus Desulfotomaculum.

A strictly anaerobic bacterium, strain OX39, was isolated with o-xylene as organic substrate and sulfate as electron acceptor from an aquifer at a former gasworks plant contaminated with aromatic hydrocarbons. Apart from o-xylene, strain OX39 grew on m-xylene and toluene and all three substrates were oxidized completely to CO2. Induction experiments indicated that o-xylene, m-xylene, and toluene degradation were initiated by different specific enzymes. Methylbenzylsuccinate was identified in supernatants of cultures grown on o-xylene and m-xylene, and benzylsuccinate was detected in supernatants of toluene-grown cells, thus indicating that degradation was initiated in all three cases by fumarate addition to the methyl group. Strain OX39 was sensitive towards sulfide and depended on Fe(II) in the medium as a scavenger of the produced sulfide. Analysis of the PCR-amplified 16S rRNA gene revealed that strain OX39 affiliates with the gram-positive endospore-forming sulfate reducers of the genus Desulfotomaculum and is the first hydrocarbonoxidizing bacterium in this genus

Extraction of DNA from soil using nanoparticles by magnetic bioseparation

Aims: To develop a simple, rapid and inexpensive soil DNA extraction protocol. Methods and Results: The protocol relies on the use of superparamagnetic silica-magnetite nanoparticles for the isolation and purification of DNA from soil samples. DNA suitable for use in molecular biology applications was obtained from a number of soil samples. Conclusions: The DNA extracted using the tested method successfully permitted the PCR amplification of a fragment of the bacterial 16S rDNA gene. The extracted DNA could also be restriction endonuclease digested. Significance and Impact of the Study: The protocol reported here is simple and permits rapid isolation of PCR-ready soil DNA. The method requires only small quantities of soil sample, is scalable and suitable for automation

Gefaehrdungstestverfahren mit Reporterbakterien fuer die Altlastensanierung: Detektion toxischer Substanzen in Bodenkontakttests Abschlussbericht

In a three year study we tested microbiological methods of indication of soil bound toxic or mutagenic compounds. We utilized marker- and reporter-gene technology in order to genetically engineer soil bacteria. Three different types of constructs were tested: (1) Sinorhizobium meliloti strains with a chromosomally inserted constitutively expressing luciferase gener (RecA"- and RecA"+); (2) Soil bacteria (Pseudomonas spp., Brevibacterium spp.) with positive selection vectors which mediated antibiotic resistances after mutation and (3) Pseudomonas fluorescens with an inserted gene cassette which conferred autoluminescence. Depending on the chromosomal insertion site, different responses towards different harmful substances could be detected. Finally, we developed a bioindication method which was based on assessing the immediate metabolic response (degradation of 95 different carbon sources) of soil extracted bacterial consortia at the community level. (orig.)SIGLEAvailable from TIB Hannover: F99B812+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Ecology and metagenomics of soil microorganisms.

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