Ribosomal Gene Sequencing

Ribosomal RNA (rRNA) gene sequencing has become the quintessential tool in microbial identification. Portions of ribosomal RNA (rRNA) genes are highly conserved for all organisms. However there have been, numerous mutations introduced over time during evolution in the variable regions of these genes. These variations are detectable by sequencing and have proven useful to differentiate between species.

rDNA sequencing involves the following steps:
  • Obtaining pure cultures
  • Lysis of microorganisms to release genomic DNA
  • PCR amplification of the target DNA
  • Sequencing reaction to incorporate dye-tagged nucleotides
  • DNA sequence determination using an automated capillary electrophoresis DNA sequencer system
  • Sequence comparison against a reference ribosomal sequence library/database

The robustness of genetic identification depends upon the size, diversity, and accuracy of the reference sequence library (RSL). A comprehensive database that encompasses a maximum number of validated sequences is required to yield the most accurate identification.

MEI has constructed a diverse, robust, comprehensive, and validated proprietary reference sequence database for both prokaryotic and eukaryotic organisms, which goes far beyond what is currently available in the industry.

The software then generates a phylogenetic table listing the genetic distance between the query sequence and genetically similar microorganisms. Using such an approach permits us to unequivocally obtain genetic identification for tens of thousands of microorganisms, with an extremely high degree of confidence and accuracy.