To assess the possibilities of a culture-independent monitoring of bacterial communities in the food chain, samples of salad from farming sites as well as corresponding, processed products in stores were analysed. The bacterial DNA was extracted using a modified soil extraction protocol. Amplification of 16S rDNA was carried out using primers specific for eubacteria and enterobacteriaceae.
Fingerprints of 200/370 bp respectively were obtained by denaturing gradient gel electrophoresis (DGGE) analysis following
PCR and nested PCR amplification. In parallel to DGGE analysis, clone libraries containing PCR fragments of the ribosomal gene were constructed and clones were screened by DGGE. DGGE analysis indicated a high diversity of bacterial communities in salad
samples. Fingerprints indicated clearly reduced diversity of bacterial communities in processed samples from markets compared to
field-grown salads.