Poster ELISA assay

The most part of vegetables are consumed fresh after harvest with bland washes, often inefficient to remove the pathogenic bacteria attached to the external skin or surfaces. The vegetables grown in open field and in contact with soil may have high possibility to carry human pathogenic bacteria. In this work an indirect Elisa assay was used to detect the presence of two human pathogens: Listeria monocytogenes and Escherichia coli  O157. Monoclonal antibodies against L. monocytogenes (LZA2) (ab11439) and E. coli  O157 (ab20976) were purchased from Abcam (Cambridge, UK). A quantity (5 g) of cucumber peel and rocket leaves from each sample were homogenized in 10 mL of 1x sterile phosphate buffered saline (1xPBS: 1 mM KH2PO4, 154 mM NaCl, 3 mM Na2HPO4, pH 7.2) and incubated for 7 h at 30????C with agitation to isolate bacteria from the matrix. An optimized ELISA protocol was used to verify the presence of these two bacteria on fresh or inoculated vegetables. The preliminary results are promising in the use of antibodies to verify the presence of bacteria in the minimally processed vegetable distribution chain.