In the last few years, we have seen the public health community (and regulatory agencies) utilize a new microbial analytical method that will ultimately be a game changer — genome sequencing (GS). By plotting the complete DNA of microorganisms and identifying minute differences between the DNA strains, it is possible to identify whether two individual samples are related with a degree of specificity unobtainable before. Unlike other methods, GS truly is the “fingerprint” which has implications in foodborne outbreaks and in regulatory verification testing.
The genome is the genetic material of the organism, the complete package. The word “genome” comes from combining the words gene and chromosome. By analysis, it is possible to plot out the entire DNA sequence of an organism. The entire DNA sequence for humans is huge. For each of our 23 chromosomes, there are between 48 to 250 million nucleotides (A,C,G,T), for a grand total of 3.2 billion nucleotides. Microorganisms, such as Salmonella, are short in comparison, around 4.5 million nucleotides depending on serotype.