Partitioning of organic chemicals into soil micro-sites - Analyses of their fate and interactions with the resident microbial communities

Principal investigators: Prof. Dr. C.C. Tebbe, Dr. R. Martens

Co-worker: Dipl.-Biol. D. Neumann

Objective:
The objective of this project is to follow the distribution and degradation of selected organic pollutants in the different micro-sites (mineral particle size classes) in soil and to characterize the structural diversity of the microbial communities present, exposed and potentially participating in the degradation processes of the pollutants.

Hypotheses:
Water solubility of the organic pollutants and soil organic matter are considered as important variables influencing fate and microbiological interactions of the pollutants in soil. These hypotheses will be tested with different organic pollutants and soil variants in experimental systems under laboratory conditions.

Scientific approach:
The organic pollutants of this study are represented by potentially biodegradable aromatic compounds which differ in their functional groups and the number of condensed benzene rings. Different SOM contents will be considered by the use of four equilibrated soil variants from an agricultural field site (Bad Lauchstädt, Halle, Germany) which had been generated by continuous different fertilization practise over more than a centennial period. Depending on the experimental question, 13C and 14C-labelled compounds and molecular techniques will be applied to locate and identify those micro-organisms which are responsible for degradation.

Cooperation within the priority programme:
Prof. Dr. M. Kästner

soildna

Crude DNA extracted from soil samples with coextracted humic material - Lysis is performed with bead beating, beads are visible at the bottom of the tubes (by courtesy of C.C. Tebbe).

SIP

After ultra speed density centrifugation, DNA fractions are collected from the gradient in order to distinguish between 12C- and 13C-labelled DNA (by courtesy of C.C. Tebbe).

sscp

Single strand conformation polymorphism of bacterial communities based on PCR-amplified, partial rRNA genes. Each lane represents the community structure ("SSCP-profile") of an environmental sample, each band corresponds to a different rRNA sequence indicating the presence of a different soil bacterium. SSCP-profiles are bordered by standardized markers, helpful to compare samples with each other (by courtesy of C.C. Tebbe).

Poster