Restriction digestion of 16S-23S short intergenic spacer of Lactobacillus rhamnosus GG. PCR amplification of rRNA spacer regions was done and the shorter amplicon was excised from an agarose gel after electrophoresis at 100 V for 45 min. Gel purified DNA was cleaved with 11 enzymes and fragments separated by electrophoresis as before. Plus and minus signs mean positive or negative cleavage of PCR amplicon. GibcoBRL 1 kb DNA ladder was used for sizing DNA fragments and molecular masses are shown at right in bp.