MOLECULAR DIFFERENTIATION OF BACTERIA BY PCR AMPLIFICATION OF THE 16S-23S RIBOSOMAL-RNA SPACER

In general, operons for prokaryotic rRNA genes contain a transcribed s pacer between 16S and 23S rRNA genes. The length and sequence of this spacer are expected to be highly variable. Polymerase chain reaction ( PCR) permits the direct amplification of spacer DNA from small amounts of genomic DNA. Data for a wide range of microorganisms were accumula ted, and the spacer lengths varied between 280 and 1300 bp. A further differentiation was achieved by a high-resolution gel electrophoresis method, single-strand conformation polymorphism (SSCP). It was possibl e to differentiate 15 Mycoplasma species, to analyze mixed samples and to distinguish Streptococcus strains and Clostridium botulinum seroty pes. Spacer analysis is a promising method for the differentiation of diverse and closely related species, and also useful in analysis of mi xed samples.