POLYMERASE CHAIN-REACTION IN FOOD MICROBIOLOGY

Many methods for the in vitro amplification of nucleic acids have been developed in recent years. Most of these methods are still at an experimental phase and only the polymerase chain reaction (PCR) is currently applied in food microbiology. The PCR has been used for the identification of isolated bacterial strains, to detect bacteria in foods in combination with cultural enrichment steps and for the direct detection of bacteria and viruses in food samples without enrichment. Especially in the case of direct detection, sample preparation has proven to be the crucial step, requiring the development of novel approaches like paramagnetic bead DNA extraction. The majority of the experiments previously performed relied on samples which had been artificially contaminated. There is therefore a general lack of validation which has been performed with naturally contaminated samples. Another field of interest is that of PCR-based DNA typing of bacterial strains. However, this promising area of research still requires isolated strains. Future work will have to concentrate on the evaluation of alternative amplification methods, the development of typing methods for nonculturable strains and the determination of the relevance of results obtained through nucleic acids analysis.