E. coli

Transgenic cells - be it prokaryotic or eukaryotic - were introduced in environmental toxicology thanks to biotechnology and genetic engineering. Such cellular systems typically combine a promoter::operator, which acts as the sensing element, with a reporter gene coding for an easily detectable protein. In the absence of toxicant the repressor is bound to the operator and expression of the reporter is blocked. Under stress conditions, the repressor is released from the operator and reporter expression is switched on either through direct interaction with the repressor or through a cascade of connected responses (signal transduction). Important aspects in the different transgenic models are a sensitive promoter, which is reliable and relevant for a certain stress, and a reporter gene allowing efficient detection of the gene product thanks to a specific substrate or, ideally detectable as such. Most, if not all, reporter proteins can be detected using optical, immunological or electrochemical methods. Many different sensing strains and cell lines of different genera have already been constructed for the detection of specific analytes such as metals, aromatic compounds and genotoxic compounds.

Silages are of great importance in animal farm forage. In Belgium, it represents the base of the cattle forage during winter, and partly during summer as well. There are different crops used for ensilage such as whole corn plant, CCM (corn cob mix), grass, sugarbeet pulp, etc. More recently, ensilaging of immature cereals has recieved increasing interest due to the low prices of grain cereals, especially of wheat and barley.

Anthropogenic as well as naturally occurring contaminants are present in our environment, for example mycotoxins and pesticides are typical food contaminants, metals and pesticides are common polluters of water and sediment. To determine the potential hazards of the individual compounds and mixtures and evaluate their toxicity different types of tests have been developed. In recent years advances in the use of in vitro cellular systems made it possible to characterise events at one of the earliest levels of molecular responses: gene expression. This research project uses E. coli and a human liver cell based stress gene profiling assays to determine the effect of chemicals and mixtures thereof on stress gene activation. The stress promoters used in these assays control transcription of genes involved in stress-related processes such as DNA damage, oxidative stress, osmotic stress, protein perturbation and tumour induction.

Validation of bacterial and human cell line based stress gene induction assays for the detection of foodborne contaminants.