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Method developed to target contaminated fresh produce

The workpackage N°1 of Quafety consists of providing diagnostic kits for the evaluation of microbial contamination and of quality degradation, and it was reached through 4 tasks. The first 2 tasks were aimed at developing fast and reliable detection methods of Listeria monocytogenes and Escherichia coli O157:H7, also through the individuation of key molecular probes able to detect genes involved in pathogenicity. The third task was aimed at using the antibodies against the pathogens involved in major outbreaks of foodborne diseases in order to detect the presence of contaminants, while the last one regards the individuation of molecular markers linked to physiological degradation of the product, such as lipid peroxidation, ascorbic acid and chlorophyll degradation.

In these days, Quafety scientists have presented the deliverable N. 1.3. The research activities described in this deliverable were carried out to develop a protein array in particular antibodies targeting specific protein associated with quality losses or with the presence of specific bacteria such as Escherichia coli or Listeria monocytogenes. Antibodies against the major outbreaks of foodborne diseases that have been traced in fresh fruits and vegetable were obtained from researchers at University of Cambridge (UK).

On the basis of transcriptome data, the research group led by Dr Antonio Ferrante at University of Milano (Italy) identified the putative genes associated with quality losses and tested them during storage conditions. The putative proteins encoded from the selected genes were studied in order to verify if they were soluble or integrated in the membranes. Among the different proteins, those that were also known in melon were selected in order to verify if the putative protein markers can be widely used or are species specific. The selected proteins for the antibodies production were such as NAC3, 4-hydroxyphenylpyruvate dioxygenase (HPPD), Asparagine synthetase and E. coli.

Results obtained showed that the detection of E. coli, in particular, the immuno-assay using capture antibody H7_5045 and detection antibody H7_5046 resulted in an increase of signal in sub-arrays incubated with bacteria compared to the negative control.

Scientists concluded that the immuno-assay for E. coli can be used but attention should be paid to possible nonspecific interaction with the detection antibody. Among the proteins associated with quality losses the best results were found for the asparagine synthetase, even if further steps for optimization are required.

It is possible to obtain further info on workpackages visiting the official project website