Detection of Food Poisoning Bacteria in Fresh Vegetables Using DNA Microarray

Abstract

A DNA microarray is a very useful tool for detecting multiple bacteria simultaneously, because it can be used to analyze the characteristics of various bacterial genes on one glass slide. This study was mainly performed to establish an assay protocol using a DNA microarray for detecting three food-borne bacteria (Salmonella enterica serovar Enteritidis, Yersinia enterocolitica, and Bacillus cereus) in fresh vegetables. To create the DNA microarray for detecting these three species of food-borne bacteria, four previously designed oligonucleotide probes corresponding to the 16S rRNA sequences of each food-borne bacterium were spotted onto a single glass slide. Bean sprouts and lettuce were used as representative fresh vegetables. Diluted cultures of the three bacteria were inoculated into the juices obtained from the fresh vegetables, and the inoculum was cultured with Soybean-Casein Digest broth to amplify the targeted bacterial 16S rRNA. RNAs extracted from the cultures were fluorescently labeled and hybridized to the DNA microarray. All three bacteria could be specifically detected in the fresh vegetable samples using this assay protocol. This DNA microarray provides a convenient approach for the simultaneous detection of food-borne bacteria in fresh vegetables in combination with conventional culture methods.