Evaluation of oligonucleotide microarray technology for the detection of foodborne bacterial pathogens

Traditional methods for detection of foodborne pathogenic bacteria, which cause disease in human, are time consuming and laborious, so there is a necessity for developing a reliable and powerful method for the rapid detection of microbial pathogens in food. The aim of this study, is designing primers to amplify the DNA encoding the 23S rDNA genes from a wide range of bacterial species and tested the ability and efficiency of 23S rDNA sequence to detection of foodborne pathogenic bacteria. The 23S rDNA sequences of 9 foodborne pathogenic bacterial species based on the GenBank DNA sequence database were used to design oligonucleotide probes by Vector NTI software. Oligonucleotide probes for each bacterial species (total 28 probes) were designed and applied to nitrocellulose membranes. Digoxigeni (DIG) labeled 23S rDNAs were amplified by polymerase chain reaction (PCR) from bacteria using two universal primers, and were hybridized to the membrane array. Escherichia coli, Listeria monocytogenes, Enterococcus faecalis, Vibrio cholerae, Shigella dysantria, Staphylococcus aurues, Salmonella enterica, Proteus vulgaris, and Bacillus cereus were used as the most common foodborne pathogens and results showed that except Shigella dysantria, the others can be detected and identified by our microarrays. The sensitivity of the microarray assay was 103 CFU of bacteria. This study showed that 23S rDNA has sufficient sequence diversity for species identification and is useful for monitoring the populations of pathogenic bacteria. Thus, the oligonucleotide microarray is a powerful tool for the rapid detection and identification of pathogens.