Pyrosequencing: nucleotide sequencing technology with bacterial genotyping applications

Pyrosequencing is a relatively new method for real-time nucleotide sequencing. It has rapidly found applications in DNA sequencing, genotyping, single nucleotide polymorphism analysis, allele quantification and whole-genome sequencing within the areas of microbiology, clinical genetics and pharmacogenetics. It is fast becoming a real alternative to the traditional Sanger sequencing method although, at present, read lengths are normally limited to approximately 70 nucleotides. The pyrosequencing method involves four main stages: first, target DNA is amplified using PCR; second, double-stranded DNA is converted to single-stranded DNA templates; third, oligonucleotide primers are hybridized to a complementary sequence of interest; and, finally, the pyrosequencing reaction itself, in which a reaction mixture of enzymes and substrates catalyses the synthesis of complementary nucleotides. Data are shown as a collection of signal peaks in a pyrogram. Pyrosequencing is increasingly used for bacterial detection, identification and typing, and, recently, a commercial system became available for the identification of bacterial isolates. Pyrosequencing can also be partially or fully automated, thus enabling the high-throughput analysis of samples. Wider use of pyrosequencing may occur in the future if longer nucleotide reads are made possible, which will enable its expansion into larger nucleotide sequencing such as multilocus sequence typing and whole-genome sequencing.