The determination of 16S ribosomal ribonucleic acid (16S rRNA) primary structures by in vitro reverse transcription requires the extraction of rRNA in pure form. Although a number of high reliable techniques have been developed for the purpose most are fairly complex, involving numerous steps and the wasting of large volumes. It describes here a RNA extraction and purification method, suitable for automatic extractors, which consistently yields reasonable amounts of pure total RNA from prokaryotes, free of DNA and RNases. The rRNA from the type strain Leuconostoc amelobiosum was isolated using this procedure. Its 16S rRNA sequence was determined and a comparative analysis with those from all currently described leuconostocs, including several atypical lactobacilli, revealed very high sequence homology with Leuconostoc citreum confirming Leuconostoc amelobiosum is phylogenetically a member of the genus Leuconostoc sensu stricto.