You may be asked to justify the request, so be certain that you have performed the preliminary tests before asking for specialized media. You will have approximately four weeks to identify unknowns 2. At the completion of the exercise you must submit your flow chart. The ultimate indicator of taxonomic classification is at the level of DNA, the genetic material. Thus if the DNA from an unknown organism is compared to the DNA from a known organism, the degree of relatedness can be determined.
Some genetic identification is accomplished through the use of DNA probes.
A labelled piece of DNA representing a unique genetic sequence is incubated with DNA from the unknown organism. Detection of the labelled probe indicates the presence of the DNA sequence in the unknown. Phylogenetic analysis of bacteria is typically performed by comparing the sequence of a portion of the 16S ribosomal RNA gene. Polymerase chain reaction is used to amplify this gene and the amplified region is then isolated and sequenced. Comparisons can be made using databases that are available on-line.