Identification of Lactobacillus isolates from the gastrointestinal tract, silage, and yoghurt by 16S-23S rRNA gene intergenic spacer region sequence comparisons

Lactobacillus isolates were identified by PCR amplification and sequencing of the region between the 16S and 23S rRNA genes (spacer region). The seque nces obtained from the isolates were compared to those of reference strains held in GenBank A similarity of 97.5% or greater was considered to provide identification. To check the reliability of the method, the V2-V3 region o f the 16S rRNA gene was amplified and sequenced in the case of isolates who se spacer region sequences were less than 99% similar to that of a referenc e strain. Confirmation of identity was obtained in all instances. Spacer re gion sequencing provided rapid and accurate identification of Lactobacillus isolates obtained from gastrointestinal, yoghurt, and silage samples. It h ad, an advantage over 16S V2-V3 sequence comparisons because it distinguish ed between isolates of Lactobacillus casei and Lactobacillus rhamnosus.